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Title:
A NOVEL PROCESS FOR THE PREPARATION OF REBAUDIOSIDE D AND OTHER RELATED NATURALLY OCCURRING SWEETENERS
Document Type and Number:
WIPO Patent Application WO/2013/102793
Kind Code:
A2
Abstract:
The present invention relates to a novel process for preparation of Rebaudioside D (RD), and other related naturally occurring sweeteners. RD is a natural sweetening agent which can decrease the bitter aftertaste of steviol glycosides. The invention relates to an efficient process that is suitable for commercial manufacturing by using readily available natural products and nontoxic reagents.

Inventors:
CHEN PING (US)
LI YINQIANG (CN)
PENG SHAOPING (CN)
Application Number:
PCT/IB2012/003095
Publication Date:
July 11, 2013
Filing Date:
December 10, 2012
Export Citation:
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Assignee:
SU ZHOU JING HONG BIOTECH CO LTD (CN)
Domestic Patent References:
WO2010146463A22010-12-23
WO2008091547A22008-07-31
WO2009038978A22009-03-26
Foreign References:
CN102060892A2011-05-18
Other References:
HIROSHI ISHIKAWA ET AL.: 'Transfructosylation of Rebaudioside A (a Sweet Glycoside of Stevia Leaves) with Microbacterim beta-Fructofuranosidase.' CHEM. PHARM. BULL. vol. 39, no. 8, August 1991, pages 2043 - 2045
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Claims:
What is claimed is:

1 . A process for preparing a compound of formula (TV):

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each ? is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, j-methoxybenzyloxy methyl, (Ci -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyJ (e.g., chioroacetyl, diehloroacetyl, trichloroacetyi, and trifluoroacetyl), arvl-acyl (e.g., benzoyl), trimethyisilyiethoxymethyi (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsiiyl, trisopropylsilyl, dimethylisopropylsilyl, diethyhsopropylsilvi, dimethylthexylsilyi, /-butyl dimethylsilyf, /-butyldiphenylsilyL trihenzyJsiiyl, tri-/?-xylyisilyi, triphenylsiJyl, diphenylmet ylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-('ί ϋ)ϋ-Π Ί ί O f.,}, and i-butoxylmethyl;

to provide a compound of formula (II),

wherein each R2 is defined as hereinabove;

(b) reacting the compound of formula (II) with a compound of formula (I),

wherein each Rj is independently a protecting group selected from benzyl, /j-methoxybenzyl (PMB), benzyioxy methyl, / methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)aikyl-acy] (e.g., chloroacetyl, dkhJoroacetyf, trichioroacetyl, and trifluoroacetyl), aryi-acyl (e.g., benzoyl), trimethylsilylethoxymethy] (SEM), silyl protecting groups (e.g., trimeihyisilyl, triethylsiivl, trisopropyisilyl, dime thy iisopropylsiiyl, diethylisopropyisilyl, dimethyhhexylsilyl, /-butyldiinethylsiiyi, /-butyldiphenylsiiyl tribenzylsilyi, tri-/?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, rris(trimethylsilyi)silyl, (2 iydroxystyry})dimethylsiiyi, 2-hydroxysryryl)disopropylsiiyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsilyl), all loxycarbonyl (alloc,

-C(0)0-CH2CH=CH2), and /-butoxylmethyl;

X is halogen, OH, aikylthio, arylthio, sulfoxide (R'S(=0)-), sulfone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triilate), OC(=NH)CCl3, OPO3H, OPO3R' or

0CH2CH2CH2CH:;;:C1¾, wherein R' is (Cj-C aikyl or aryl, and the anonieric carbon attached with X can be either a or β configuration;

to pro vide a compound of formula (111),

wherein ¾ and R2 are defined as hereinabove;

(c) removing the protecting groups R; and R2 of the compound of formula (III) to provide the compound of formula (TV).

2. A process for preparing a com ound of formula (X):

comprising:

(a) selectively hydrolyzi ST),

(VII)

wherein each R2 is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, /j-methoxybenzyloxy methyl, (d-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, diehloroacetvl, trichioroaceiyi, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropyisilyl, dimethyiisopropylsiiyl, diethylisopropylsilyl, dimethylthexylsilyi, i-butyidimethylsilyi, ?-butyldiphenylsilyl, tribenzylsiiyl, tri- ?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmetbylsilyl, iris(trimethylsilyi)silyl, (2 iydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropylsiiyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsilyl), all loxycarbonyl (alloc,

-C(0)0-CH2CH=CH2), and /-butoxylmethyl;

to provide a compound of formula (II),

wherein each R2 is defined as hereinabove;

(b) reacting the compound of formula II) with a compound of formula (XI),

wherein each R\ is independently a protecting group selected from benzyl ?-methoxybenzyl (PMB), benzyfoxy methyl, j-methoxybenzy3oxy methyl, (Ci-C4)a1kyl-acyl (e.g., acetyl), halogen substituted (Ci -C^jalkyl-acyl (e.g., eliloroaeetyl, dicbloroacetyl, trichloroacety], and trifluoroacetyl), aryl-acyl (e.g., benzoyl), irimeihyisilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethyfs ly], trietbylsilyl, trisopropyis lyl, dimethyfisopropylsifyl, diethylisopropyf si lyl, dimethylthexylsilyi, i-butyldimethy Isifyl, t-bufy ldipheny Isifyl, iribenzylsilyl, rfi-p-xyiyisiryi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyi, tris(trimethylsiiyi)silyl, (2-hydroxystyryI)dimethylsilyl> 2-hydroxystyryl)disopropylsilyl> /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

'ί ί) )ί)-Π i.'O ! ( "! !■;. and i-butoxyimethyl.;

X is halogen, OH, alkylthio, aryithio, sulfoxide (R'S(-0)-), sulfone (R'S(-0)2-), sulfonate (e.g., mesylate, tosylate, or inflate), GO. i K Ch. OPO3H, OPOjR' or OCH2CH2CH2CH=CH¾ wherein R' is (Ci-C4)alkyl or and, and the anomerie carbon attached with X can be either or β configuration;

to provide a compound of fo

wherein Ri and R2 are defined as hereinabove;

(c) removing the protecting groups R; and R2 of the compound of formula (HI) to provide the compound of formula (X).

3. A process for preparing a compound of formula (ΧΤΠ):

(XIII)

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each R2 is independently a protecting group selected from benzyl, />-methoxybenzy3 (PMB), benzyloxy methyl, p-methoxybenz loxy methyl, (Ci-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chioroacetyi, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyi, diethyiisopropyisiiyl, dimetliyithexyisilyl, i-butyldimefhylsiiyL /-buiyldiphenylsiiyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsiiyl)si]yl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butylm eth oxypheny is i ly 1 , i-butoxydiplienyi si lyl ), al lyl oxycarbony 1 (al loc,

··( '· ())(( I ! >c: ί 1 and i-butoxylmethyl;

to provide a compound of formula (II),

wherein each R2 is defined as hereinabove;

(b) reacting the compoun of formula (XiV),

wherein each Rj is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, j-methoxybenzyloxy methyl, (Ci-C-4)alkyl-acyi (e.g., acetyl), halogen substituted (Ci-C^aikyi-aeyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyi, diethyiisopropyisiiyl, dimetliyithexyisilyl, i-butyldimethylsilyi, i-butyldiphenylsilyl, tribenzylsilyl, tri-o-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyi, tris(trimethylsiiyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylm eth oxypheny Isi lyl, /-butoxydiplienylsilyl), allyloxycarbonyl (alloc,

•C'i O M i i CM..), and i-butoxyimethyl; X is halogen, OH, aikylthio, aryithio, sulfoxide (R'S(= ))-), sultone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triflate), GO \mCCi .. OPO3H, OPO3R' or

OCH2CH2CH2CH=CH2, wherein R' is (Ci-C4)alkyl or aryL and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XV),

wherein Ri and R? are defined as hereinabove;

(c) remo v ing the protecting groups R-, and R2 of the compound of formula (ill) to provide the compound of formula (XIII).

4. A process for preparing a compound of formula (XVI):

comprising:

(a) selectively hydrolyzmg a compound of formula (VII),

wherein each R? is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)aIkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxyinethyl (SEM), siiyl protecting groups (e.g., trimethylsiiyl, triethylsifyl, trisopropylsiivi, dimethyiisopropylsiiyf, diethylisopropylsiJyl, dinietliylthexylsiiyl, i-butyldimet ylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri- ?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsifyi)silyl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenyl si lyl ), al lyl oxycarbony 1 (al loc,

•C 'i O M i i ( I I .). and i-butoxyrmethyl;

to provide a compound of formula (Π),

wherein each R2 is defined as hereinabcn

(b) reacting the compound of formula 11) with a compound of formula ( XV U s.

wherein each Ri is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, /j-methoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), siiyl protecting groups (e.g., trimethylsiiyl, triethylsifyl, trisopropylsiJyl, dimethylisopropylsilyL diethylisopropylsilyl, dimethylthexyisilyl, i-butyldimefhylsilyL /-bu yldiphenylsiiyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyl)silyi, (2-bydroxystyryl)dimet ylsilyl, 2-hydroxystyryl)disopropylsilyl, ί-butylmethoxyphenylsily], /-butoxydiplienylsilyl), allyloxycarbonyl (alloc,

-( i ())0-(] | )(l ! C! i >). and i-butoxylmetbyl;

X is halogen, OH, alkylthio, arylthio, sulfoxide (R'S(=0)-), sulfone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl3, OP03H, OPO3R' or

OC¾CH2CH2CH ¾, wherein R' is (Cj-C4)alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XVIII),

(XVIII)

wherein R] and R2 are defined as hereinabove;

(c) removing the protecting groups R; and R2 of the compound of formula (XVIII) to provide the compound of formula (XVI).

5. A process for preparing a compound of formula (XIX):

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each R2 is independently a protecting group selected from benzyl, /?-methoxybenzyl (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (Ci-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C^jalkyi-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), irimeihyisilylethoxymethyl (SEM), siiyl protecting groups (e.g., trimethyisilyl, triethylsilyl, trisopropyisiiyl, dimethyiisopropylsiiyl, diethylisopropyf si lyl, dimethyithexylsiiyl, i-butyldimethy lsiiyl, t-bufy ldipheny Isifyl, iribenzylsilyl, rri-p-xyiyisiryi, triphenyisilyl, diphenylmetlxylsiryl, di-i-butylmethylsilyi, tris(trimethylsilyi)silyl, (2-hydroxystyryl)dimethylsilyl> 2-hydroxystyryl)disopropylsilyl, /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-Ci O iO-CU .( Ή Cn . ;. and i-butoxyimethyl;

to pro vide a compound of formula (II),

wherein each R? is defined as hereinabove;

(b) reacting the compo formula (XX),

wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsifyl, trisopropylsilyl, dimethylisopropylsilyf, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri- :?-x y y 1 s ily L triphenyisilyl, diphenylmethylsilyl, di-/-butylmethylsilyi, tris(trimethylsifyl)silyl, (2-bydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenyl si lyl ), al lyl oxycarbo y 1 (al loc,

•C 'i O M i i ( I I .). and i-butoxyimethyl;

X is halogen, OH, alkylthio, arylthio, sulfoxide (R.'S(=0)-), sulfone (R'S(=0)2-)5 sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl3, GPChH, OPO3R' or

OCH2CH2CH2CH=CH2, wherem R' is (Ci -C4)alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XXI),

wherein R] and R2 are defined as hereinabove;

(c) removing the protecting groups Rj and R2 of the compound of formula (HI) to provide the compound of formula (XIX).

6. The process of any one of claims 1 -5, wherein in step (b), the compound of fonnula (II) is reacted without the use of Ag2C03.

7. The process of any one of claims 1-6, wherein each Ri is independently

(Ci-C al l-acyl (i.e., (Ci-C4)alkyl-C(=0)-) or phenyl.

8. The process of any one of claims 1 -7, wherein each R? is independently

(C]-C-4)alkyl-acyl (i.e., {(' ·( ..!asks !·< i ())·) or phenyl.

9. The process of any one of claims 1 -8, wherein each Ri is independently acetyl iCU.Ci ())-).

10. The process of any one of claims 1 -9, wherein each R2 is independently acetyl (CIUO ()!-!.

11. The process of any one of claims 1-10, wherein the compound of formula (VII) is prepared by:

(a) hydrolyzing a compound of formula (VIII),

to provide a compound of formula IX),

(b) protecting the OH groups of the compound of formula (IX) to provide the compound of formula (VII),

wherein R2 is defined as hereinabove.

A process of preparing a mpound of formula (III),

comprising reacting a compo

(Π)

wherein each R2 is independently a protecting group selected from benzyl,

-methoxybenzyi (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (C1-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chioroacetyl, dichloroacetyl, rrichioroacetyl, and triiluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylemoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsiJyl, trisopropylsilyl, dimethylisopropyisilyi, dieihyiisopropylsiiyi, dimethylthexyisilyl, i-butyldimethylsilyl, /-butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsiiyl, triphenylsilyl, diphenylmethyisilyl, di-/-butylnietliylsilyl, tris(trimethylsi]yl)silyl, (2-hydroxystyryl)dimethylsily], 2-bydroxystyryl)disopropylsilyl, r-butylmethoxypheny3silyl, i-butoxydiphenylsil l), allyloxycarbonyl (alloc, -C(0)0-CH2CH=CH2), and i-butoxylmethyl;

(i) with a compound of formula se of Ag2C03, (la)

wherein each Ri is independently a protecting group selected from benzyl, jP-methoxybenzyl (PMB), benzyioxy methyl, >-m.ethoxybenzy3oxy methyl, (Cj -C4)alkyi-acyl (e.g., acetyl), halogen substituted (e.g., chioroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethyisilyl, triethyisilyl, trisopropylsilyl, dimethylisopropvisiiyi, diethylisopropyisiivi, dimethylihexyisiiyi, /-butyldimethyisiiyl,

1- butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tris(trimethylsily3)siiyl, (2-hydroxystyryl)dimethylsi3yl,

2- hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiplienyJsslyl), allyloxycarbonyl (alloc, ~C(0)0-CH2CH=CH2), and i-butoxylmethyl; and ihe anomeric carbon attached with Br can be either a or β configuration;

or (ii) with a compound of formula

wherein each R] is as defined hereinabove;

or (iii) with a compound of formu

wherein each Ri is as defined hereinabove;

to provide a compound of formula (III).

13. The process of claim 12, wherein the compound of formula (II) is reacted with the compound of formula (la) in the presence of a phase transferring reagent and an inorganic base.

14. The process of claim 13, wherein the phase transferring reagent is TBAB, TBAC, TBAI, or TEBAC; and the inorganic base is KHCO3, K2CO3, K3PO4, or KH2PO4.

15. The process of claim 12, wherein the compound of formula (II) is reac ted with the compound of formula (lb) in the presence of NIS and an acid.

1 6. The process of claim 12, wherein the compound of formula (Π) is reacted with the compound of formula (Id) in the presence of TBSOTf (CFsSOsSiMe^-Bu), TMSOTf, or

TfOH.

1 7. The process of any one of claims 12- 16, further comprising removing the protecting groups R] and R2 of the compound of formula (III) to provide a compound of formula (I V),

1 8. The process of any one of claims 12- 17, wherein in the compound of Formulae (la), (lb) or (Id), the anomeric carbon attached with Br is a configuration.

19. The process of any one of claims 12- 18, wherein the compound of formula (II) is prepared by selectively hydrolyzing a compound of formula (VII),

wherein each R? is independently a protecting group selected from benzyl, jP-methoxybenzyl (PMB), benzyioxy methyl, ?-methoxybenzyloxy methyl, (Ci-d)alkyi- (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethyf silyl, trisopropylsilyl, dimethylisopropylsily], diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl,

1- butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tiis(trimethylsilyl)sifyl, (2-hydroxystyryl)dimethylsi]yl,

2- hydroxystyryj.)disopropylsilyl, i-burylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -C(0)0-CH2CH=CH2), and i-butoxylmethyl.

20. The process of claim 19, wherem the compound of formula (VTI) is prepared by:

(a) hydro lyzing a compound of formula (VIII),

(b) protecting the OH groups of the compound of formula (IX) to provide the compound of formula (VII),

wherein R2 is defined as hereinabove.

21. The process of claim 12-20, wherem each Rj is independently (Ci-C4)alkyl-acyl (i.e., or phenyl.

22. The process of any one of claims 12-21, wherein each R2 is independently

(Ci-C4)alkyl-acyi (i.e., {(' ·( ..!asks !·< i ())·) or phenyl.

23. The process of any one of claims 12-22, wherein each R; is independently acetyl (CU.C( ())·>.

24. The process of any one of claims 12-23, wherein each R? is independently acetyl (CIUO <)H.

Description:
A Novel Process for the Preparation of Rebaudioside D and Other Related Naturally

€)ecurriiig Sweeteners

Cross Reference to Related Applications

[8001] This application claims the benefit of Chinese Application No. 201 1 10408176.7, filed December 9, 2.01 1 , and Li.S. Provisional Patent Application No. 61 /579,016, filed December 22, 2011, the entire contents of which are hereby incorporated by reference herein.

Field of the Invention 0002] The present invention relates to a novel process for preparation of Rebaudioside D (RD), and other related naturally occurring sweeteners (such as Rebaudioside M,

Rebaudioside N, Rebaudioside I, Rebaudioside O, and etc.). RD is a natural sweetening agent which can decrease the bitter aftertaste of steviol glycosides. The invention relates to an efficient process that is suitable for commercial manufacturing by using readily available natural products and nontoxic reagents.

Background of the Invention

[8003] Steviol glycosides are considered high intensity sweeteners and have been used for several years in a number of countries as a sweetener for a range of food products. The aqueous solutions of Steviol glycoside preparations are 200 to 300 times sweeter than sucrose under identical conditions. With this significant advantage, Stevia has garnered attention with the rise in demand for lo carbohydrate, low sugar food alternatives.

8004] Among the different kind of Steviol glycosides, Stevioside (ST) and Rebaudioside A (RA) are the principal sweetening compounds and generally accompanied by smaller amounts of other Steviol glycosides. Both of them have slow er onset and longer duration than that of sugar, and are deemed very close to sucrose. Unfortunately, compositions that contain Stevioside and Rebaudioside A (RA) typically have a bitter aftertaste at high concentration which greatly limited their application. It has been found that by increasing the amount of Rebaudioside D (ano ther Steviol glycosides in Stevia) in a composition that includes rebaudioside A and/or other stevia components can greatly overcome the bitter aftertaste.

Rebaudioside A (RA) Stevioside (ST) Rebaudioside D (RD)

[8006] One method of preparing RD is by extraction from Stevia Rebaudian, followed by separation and purification. Because of the extremely low composition (<0.5%) of RD in Stevia Rebaudian, this method can only produce a limited quantity of RD and cannot meet the soaring demand for RD. Another method relates to the semi-synthesis of RD and is disclosed in US2010/0316782 (WO2010/146463). As shown in Scheme 1, RA is converted to Rebaudioside B (RB) by saponification, followed by acerylation to afford acetyl RD. Condensation of acetylated RB with aceivlated Sophorose bromide 1 in the presence of silver carbonate provides fully acetylated RD. After de-acetylation using NaOMe, RD is obtained in 8.1% yield.

- - Scheme

[8007] The major drawbacks of this process include, but are not limited to, the following:

1. The yield of reacting acetylated RB with acetylated sophorose bromide I by esterification and followed by de-aeetylation with NaOMe to afford RD, is as low as 8.1%, which is not suitable for commercial manufacturing,

2. Silver carbonate is required in a key esterification reaction, which results in a high material cost for the process.

3. Introduction of a heavy metal (e.g., silver) in the process increases the risk of unacceptable high le vel of residual silver metal for human consumption.

4. The purification of final product RD is carried out by column chromatography, which is not suitable for commercial production.

[0008] There is a need for an efficient process for making RD and other naturally occurring sweeteners which does not require the use of heavy metal and which is suitable for commercial manufacturing. The present invention relates to an improved process for the preparation of RD and other naturally occurring sweeteners using a novel synthetic strategy, which residt in high yields while eliminating the use of heavy metal as a reagent. This process is free of chromatographic purification, and suitable for commercial manufacturing. Summary of the Invention

In one aspect, the present invention provides to a process for preparin compound of formula (TV) (i.e., RD):

comprising:

(a) selectively hydrolyzi T ),

i v i n

wherein each R 2 is independently a protecting group selected from benzyl, MtnethoxybenzyJ (PMB), benzyloxy methyl, p-methoxybenz loxy methyl, (Ci-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyL dichloroacetyl, trichloroacety], and trifluoroaeetyl), aryl-aeyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trirnethylsilyl, triethylsiiyl, trisopropyisilyl, dinietliyiisopropylsiiyi, diethylisopropyisilyl, dimethylthexylsilyl, i-butyldimethylsiiyi, /-butyldiphenylsiiyl, tribenzylsilyi, tri-p-xylylsilyl, triplienylsilyl, diphenylmethylsily , di-i-butylmethylsilyl, tris(trrmethylsiiyi)silyl, (2-hydroxysiyiyl)dimethylsilyi, 2-hydroxystyiyl)disopropyisiiyL /-butylmethoxyphe ylsilyl, i-butoxydiphenylsilyi), allyloxycarbonyl (alloc,

-C ' i O iO-C Π ·Π ! ( ! !■;. and i-butoxyfmethyi;

to provide a compound of formula (II),

wherein each R 2 is defined as hereinabove;

(b) reacting the compound of formula (II) with a compound of formula (I),

wherein each Rj is independently a protecting group selected from benzyl, *?-irtethoxybenzyi (PMB), benzyloxy methyl, / methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C4)aikyl-acy] (e.g., chloroacetyl, dichloroacetyf, trichioroacetyl, and trifluoroacetyl), aryi-acyl (e.g., benzoyl), trimethylsilylethoxymethy] (SEM), silyl protecting groups (e.g., trimeihyisilyl, triefhylsiiyl, trisopropyisilyl, dime thy iisopropylsiiyl, diethylisopropylsilyl, dimethyhhexylsilyl, /-butyldimethylsilyi, /-butyldiphenylsilyl tribenzylsilyl, tri-/?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, iris(trimethylsilyi)silyl, (2 iydroxystyryl)dimethylsiiyi, 2-hydroxystyryl)disopropylsiiyl, i-butyhnethoxyphenylsilyl, /-butoxydiphenylsilyl), all loxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and /-butoxylmethyl;

X is halogen, OH, aikylthio, arylthio, sulfoxide (R'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), 0C(=NH)CC1 3 , OP0 3 H, OPO3R' or

0CH2CH2CH2CH :;;: C1¾, wherein R' is (Cj-C alkyl or aryl, and the anonieric carbon attached with X can be either a or β configuration;

to pro vide a compound of formula (111),

wherein ¾ and R 2 are defined as hereinabove;

(c) removing the protecting groups R; and R 2 of the compound of formula (III) to provide the compound of formula (TV).

[801Θ] In another aspect, the present invention provides a process of preparing a compound of formula (X):

comprising:

(a) selectively hydrolyz II),

(VII)

wherein each R 2 is independently a protecting group selected from benzyl, ?-methoxybenzyl (PMB), benzyloxy methyl, / methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyi, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethyhsopropylsilyi, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-butyldiphenylsiiyl, iribenzylsilyl, rri-p-xylylsilyl, triphenyisilyl, diphenylnietliylsilyl, di-i-butylmetliylsilyi, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsiTyl, /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-Ci O iO-CU .(Ή ( " > [ . ;. and i-butoxyimethyl;

to provide a compound of

wherein each R? is defined as hereinabove;

(b) reacting the compound of formula IT) with a compound of formula (XT),

wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyl (PMB), benzyloxy methyl, /j-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyfs lylethoxymethyl (SEM), silyf protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyi, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimefhylsiiyL i-buryldiphenylsilyl, iribenzylsilyl, tri- ?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsifyl)silyl, (2-hydroxystyryl)dimethylsilyI, 2-hydroxysryryl)disopropyIsilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiplienyi si lyl ), al lyl oxycarbony 1 (al loc,

··( ' · ())()· ( Π ·( H < Π >). and i-butoxyimethyl; X is halogen, OH, aikylthio, arylthio, sulfoxide (R'S(= ))-), sulfone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or trsflate), GO \ mCCi .. OPO3H, OPO3R' or

OCH2CH2CH2CH=CH2, wherein R' is (Ci-C4)alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of fo

wherein i and R 2 are defined as hereinabove;

(c) removing the protectmg groups Ri and R? of the compound of formula (HI) to provide the compound of formula (X).

[8011 In another aspect, the present invention provides a process for preparing a compound of formula (XIII)

comprising:

(a) selectively hydrolyzing a compound of formula (VTI),

wherein each R 2 is independently a protecting group selected from benzyl, Mnethoxybenzyl (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (Ci-C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (e.g., eliloroaeetyl, dichloroacetyl, trichloroacety], and irifluoroacetyl), aryl-acyl (e.g., benzoyl), irimeihyisilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethyisilyl, triethylsilyl, trisopropyisilyl, dimethylisopropylsilyl, diethylisopropyf si lyl, dimethyfthexylsilyl, i-butyldimethy Isifyl, t-bufy ldipheny Isifyl, iribenzylsilyl, rri-p-xyiyisiryi, triphenyisilyl, diphenylnietliylsilyl, di-i-butylmethylsilyi, tris(trimethylsilyi)silyl, (2-hydroxystyryl)dimethylsilyl > 2-hydroxystyryl)disopropylsilyl, /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-Ci O iO-CU .(Ή ( " > [ . ;. and i-butoxyimethyl;

to pro vide a compound of formula (II),

wherein each R? is defined as hereinabove;

(b) reacting the compoun of formula (XIV),

wherein each Ri is independently a protecting group selected from benzyl, Mtnethoxybenzyl (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (Ci-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-Ctjalkyl-acyl (e.g., eliloroaeetyl, dichloroacetyl, trichloroacety 1, and trifluoroacetyl), aryl-acyi (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyi, diethyiisopropyisiiyl, dinietliyithexyisilyl, i-butyldimefhylsiiyL /-buiyldiphenylsiiyi, tribenzylsilyl, tri-/?-xylylsilyl, triphenylsilyl, diphenylmethylsilyi, di-/-butylmethylsilyi, tris(trimethylsiiyl)si]yl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny is i ly 1 , i-butoxydiphenylsi lyl ), al lyl oxycarbony 1 (al loc,

··( ' · ( )) ( ( I ! >c: ί 1 and i-butoxylmethyl;

X is halogen, OH, alkylthio, arylthio, sulfoxide (R.'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CC , OP0 3 H, OPO 3 R' or

OCH2CH2CH 2 CH=CH2, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XV),

wherein Rj and R. 2 are defined as hereinabove;

(c) removing the protecting groups Ri and 2 of the compound of formula (III) to provide the compound of formula ( XI H i.

[0012] In another aspect, the present invention provides a process for preparing a compound of formula (XVI)

(XVI) comprising:

(a) selectively hydrolyz II),

(VII)

wherein each R 2 is independently a protecting group selected from benzyl, /j-methoxybenzyl (PMB), benzyioxy methyl, j-methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., irimeihyisilyl, triefhylsilyl, trisopropyisilyl, dime thy lisopropylsilyl, diethylisopropylsilyl, dimethyhhexylsilyl, /-butyldimethylsilyi, /-butyldtphenylsilyl tribenzylsilyl, tri- ?-xylyisilyI, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsiIyl, 2-hydroxys†yryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and /-butoxylmethyl;

to provide a compound of for

(II)

wherein each R 2 is defined as hereinabove;

(b) reacting the compound of formula (II) with a compound of formula (XVII), wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyl (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxjmethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsifyl, trisopropylsilyl, dimethylisopropylsilyf, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-buryldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-/-butylmethylsilyl, trisitrimethylsilynsilyi, (2-bydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenyl si lyl ), al lyl oxycarbony 1 (al loc,

•C ' i O M i i ( I I .). and i-butoxyimethyl;

X is halogen, OH, aikylthio, aryithio, sulfoxide (R.'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , GPChH, OPO3R' or

OCH 2 CH 2 CH 2 CH=CH2, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of

(XVIII)

wherein Ri and R2 are defined as hereinabove;

(c) removing the protecting groups R; and R 2 of the compound of formula (XVLll) to provide the compound of formula (XVI).

[8013] In another aspect, the present invention provides a process for preparing a compound of formula (XIX):

comprising:

(a) selectively hydrolyzi IT),

(VII)

wherein each R 2 is independently a protecting group selected from benzyl, -methoxybetizyJ (PMB), benzyloxy methyl, /j-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyi, trichloroacetyl, and trif!uoroacety]), aryl-acyi (e.g., benzoyl), trimethyis lylethoxymethyl (SEM), silyf protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyi, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimefhylsilyL i-butyldiphenylsilyl, tribenzylsilyl, tri- »-xylylsilyl, triphenyfsilyl, dipheiiylmethylsilyl, di-/-butylmethy]silyl, tris(trimethylsiiyl)si]yl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxvcarbonyi (alloc,

··( ' · ( )) ( ( I ! >c: ί 1 < \ \ .). and i-butoxylmethyl;

to provide a compound of formula (II),

wherein each R 2 is defined as hereinabove:

(b) reacting the compound of formula (II) with a compound of formula (

wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethyisilyl, triethylsifyl, trisopropyisilyi, dimethyiisopropylsiiyf, diethylisopropyisilyl, dimethyithexyisilyl, i-butyldimefhylsiiyL /-buiyldiphenylsiiyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-/-butylmethylsilyl, tris(trimethylsiiyl)si]yl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly I , i-butoxydiphenyl si lyl ), al lyl oxycarbony l (al loc,

··( ' · ( )) ( ( i l 'C H < l b), and i-butoxylmethyl;

X is halogen, OH, alkylthio, arylthio, sulfoxide (R'8( ;;; Q)-), sulforie (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CC , OP0 3 H, OPO 3 R' or

OCH 2 CH 2 CH 2 CH=CH2, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XXI),

wherein Ri and R? are defined as hereinabove;

(c) remo v ing the protecting groups R-, and R 2 of the compound of fomiuia (111) to provide the compound of formula (XIX).

[0014] in another aspect, the present invention provides a process of preparing a compound of formula (III),

comprising reacting a compound of formula (II),

wherein each R 2 is independently a protecting group selected from benzyl,

/?-methoxybenzyl (PMB), benzvloxy methyl, ?-methoxybenzyloxy methyl, (Ci -Chalky 1-acyi (e.g., acetyl), halogen substituted (Ci-C^a!kyi-aeyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), atyl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., tximethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropvisilyi, dietliyiisopropylsilyi, dimethyithexylsilyl, /-butyldimetliylsilyl,

1- butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tris(trimethylsily])siiyl, (2-hydroxystyryl)dimethylsi]yl,

2- hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -C(0)0-CH?CH=CH2), and i-butoxylmethyl;

with a compound of formula (la),

wherein each Ri is independently a protecting group selected from benzyl,

/?-methoxybenzyl (PMB), benzvloxy methyl, ?-methoxybenzyloxy methyl, (Ci -Chalky i-acyi (e.g., acetyl), halogen substituted (Ci-C^alkyl-acy] (e.g., chforoacetyl, dicliloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropvisilyi, diethyhsopropylsilyl, dimethyithexylsilyl, /-butyldimethylsilyl,

1- butyidiphenylsilyi tribenzylsilyl, tri-p-xylylsiiyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tris(trimethylsilyl)siiyl, (2-hydroxystyryl)dimethylsilyl,

2- hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, f-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -Qi^O-CB^CB^CB^), and i-butoxyfmethyl; and the anomeric carbon attached with Br can be either a or β configuration;

to provide a compound of formula (III) without the use of AguCOs.

[8015] In yet another aspect, the present invention provides a process for a process of preparing a compound of formula (Til),

comprising reacting a compo

(Π)

wherein each R? is independently a protecting group selected from benzyl,

/j-metboxybenzyl (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (C 1 -C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C 4 )alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichioroaeetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, tnethylsilyl, tnsopropylsiiyl, diraethylisopropylsilyi, dietliylisopropylsilyl, dimethyithexylsiiyi, i-butyldimethylsilyl,

1- butyldiphenylsilyl, tribenzyisilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmeihyisilyl, di-/-butylinethyisilyl, tris(trimethylsiiyl)siiyL (2-hydroxystyryl)dimethylsilyl,

2- bydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyi), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and t-butoxylmethyl;

with a compound of formula (lb),

wherein each Ri is independently a protecting group from benzyl, >-methoxybenzyl (PMB), benzyloxy methyl, /?-methoxybenzyloxy methyl, (d-C^alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C4)aikyl-acy] (e.g., chloroacetyl, dkhloroacetyf, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylet oxymet y] (SEM), silyl protecting groups (e.g., rrimeihyisilyl, triethylsilyl, trisopropyisilyl, dimemylisopropylsiiyi, diethylisopropyisilyl, dimethyhhexylsilyl, i-butyldimethylsilyl, /-butyldiphenylsiiyl tribenzylsilyl, tri-/?-xylyisilyi, triphenylsilyl, diphenyhnethylsilyl, di-i-butylmethylsilyf, tris(triinethylsilyl)sily1, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butyhnethoxyphenylsilyl, /-butoxydiphenylsilyl), all loxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and i-butoxylmethyl, and the anoraeric carbon attached with S can be either a or β configuration;

to provide a compound of formula (III).

[801 ] In yet another aspect, the present invention provides a process of preparing a compound of formula (III),

comprising reacting a comp

(Π)

wherein each R 2 independently a protecting group selected from benzyl,

p-methoxybenzyl (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (CrC^aHqrl-ac i (e.g., acetyl), halogen substituted (Ci-C )alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethy] (SEM), siiyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsiiyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimet ylthexylsilyl, i-butyldimethylsilyl,

1- butyldiphenylsilyl, iribenzylsilyl, tri-p-xyiylsiiyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl,

2- hydroxystyryl)disopropy]silyl, i-buty3methox>phenylsilyl, i-butoxydiphenylsiiyl), allyloxycarbony] (alloc, -C(0)0-CH=CH 2 ), and i-butoxylmetbyl;

with a compound of formula (Id),

wherein each Ri is independently a protecting group selected from benzyl, p-methoxybenzyi (PMB), benzyloxy methyl, p-methoxybenzyloxy methyl, (Ci-C4)alkyl- (e.g., acetyl), halogen substituted (Ci-C 4 )alkyl-acyl (e.g., chioroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethy] (SEM), siiyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsiiyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, /-butyldipheiiylsilyl, tribenzylsilyi, tri- ?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsiiyl, tris(trimethylsi1yl)silyi, (2~hydroxystyiyl)dimethyisily1,

2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -C{0)0-CH 2 CH-CH 2 ), and i-butoxylmethyl; and the anomeric carbon attached with OH can be either a or β configuration;

to provide the compound of formula (Til).

[8(517] In one aspect, the present invention provides to a process for preparing a compound of formula (X) (i.e., Rebaudioside M, RM):

comprising:

(a) reacting the compoun

(Π)

wherein each R 2 is independently a protecting group selected from benzyl, j-methoxybenzyl (PMB), henzyloxy methyl, ?-methoxybenzy]oxy methyl, (C j -C 4 )aU yl-aeyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., ehloroaeetyi, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., trimethylsiiyi, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropyisilyl, dimethvlihexylsilyl, i-butyldimetliylsiiyi, i-butyldipheiiylsiiyL iribenzylsilyl, tri-p-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyL tris(trimethylsilyf)s ly], (2-hydroxystyryi)d methylsifyl, 2-hydroxystyryi)disopropylsifyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

·(·(( ) !( ) ·(·! i .CH CM.. ), and t-butoxylmethyl;

with a compound of formula (XI

(XI) wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)aIkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroaceryl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsiiyl, triethylsifyl, trisopropylsiivi, dimethyiisopropylsiiyf, diethyJisopropylsiJyl, dinietliylthexylsiiyl, i-butyldimet ylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsifyi)silyl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenyl si lyl ), al lyl oxycarbony 1 (al loc,

•ί ' ί ϋ Μ Ή ( i i >). and i-butoxylmethyl;

X is halogen, OH, alkylthio, arylthio, sulfoxide (R.'S(=0)-), sulfone (R'S(^O)?-), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , GPChH, OPO3R' or

OCH2CH2CH 2 CH=CH2, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula ( % ! ! }.

wherein i and R 2 are defined as hereinabove; and

(b) removing the protecting groups R; and R2 of the compound of formula (XII) to provide the compound of formula (X).

[0018; In another aspect, the present invention provides to a process for preparing a compound of formula (XIII) (i.e., Rebaudioside N, RN):

comprising:

(a) reacting the compoun

(Π)

wherein each R2 is independently a protecting group selected from benzyl, p-methoxybeiizyl (PMB), benzyloxy methyl, ?-methoxybenzy]oxy methyl, (C j -C 4 )aU yl-aeyl (e.g., acetyl), halogen substituted (Ci-C4)alkyI-acyl (e.g., chloroaeetyL dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., trimethylsilyl, tr ethyisilyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropyisilyl, dimethvlihexylsilyl, i-butyldimetliylsiiyi, i-butyldipheiiylsiiyL iribenzylsilyl, tri-p-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyL tris(trimethylsilyf)s ly], (2-hydroxystyryl)d metliylsifyl, 2-hydroxystyryi)disopropylsifyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyioxycarhonyl (alloc,

■( ·(( ) !( )■ (·! i .CH CM.. ), and -butoxyimethyl;

with a compound of formula (XIV),

(XIV) wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzy] (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (Ci-C4)alkyl-acyi (e.g., acetyl), halogen substituted (Cj-C4)aIkyl-acyl (e.g., chloroacetyi, diehloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsifyl, trisopropylsilyl, diniethylisopropylsilyf, diethyiisopropylsiJyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenyl iethylsilyl, di-/-butylmethylsilyi, tris(trimethylsilyl)si]yl, (2-hydroxyst Tyd)dimethylsilyf, 2-hydroxys1yiyl)disopropyfsilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenylsi lyl ), al lyl oxycarbony 1 (al loc,

•C ' i O M i l ( ' Π '). and i-butoxylmethyi;

X is halogen, OH, alk lthio, arylthio, sulfoxide (R.'S(=0)-), sulfone (R'S(^O)?-), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , GPChH, OPO3R.' or

QCH 2 CH2C¾CH=C3¾, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XV),

wherein Ri and R2 are defined as hereinabove; and

(b) removing the protecting groups Rj and R? of the compound of formula (XV) to provide the compound of formula (XIII).

[6019] In another aspect, the present invention provides to a process for preparing a compound of formula (XVI) (i.e., Rebaudioside I, RI):

comprising:

(a) reacting the compound of formula (II),

wherein each R?, is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (e.g., chloroacetyi, diehloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilyleihoxymeihyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsifyl, trisopropyisiivi, dimethyiisopropylsiiyf, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsiiyL /-buiyldiphenylsiiyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenylsilyl, diphenylniethylsilyl, di-/-butylmethylsilyl, tris(trimethylsifyi)silyl, (2-hydroxystyTyd)dimethylsiiyf, 2~hydiOxystyryl)di8opropyisiiyl, i-butylm eth oxypheny J.s i ly 1 , i-butoxydiphenyl si lyl ), al ly] oxycarbo ny 1 (al loc,

··( ' · () ) () · ( i l 'C H < Π > ) . and i-butoxylmethyl;

with a compound of fonnula (XVII),

R 0. A— -^ ^ -ο-~-ι--γ- -- Α

,6 (XVII)

wherein each Ri is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, ^-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C4)aikyl-acy] (e.g., chloroacetyl, dkhJoroacetyf, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylet oxymethyl (SEM), silyl protecting groups (e.g., rrimeihyisilyl, triethylsilyl, trisopropyisilyl, dime thy iisopropylsiiyl, diethylisopropyisilyl, dimethyhhexylsilyl, /-butyldimethylsiiyl, /-butyldiphenylsiiyL tribenzylsilyi, tri-/?-xylyisilyI, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsily{)sily1, (2-hydroxystyryl)dimethylsi{yl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsiiyl), all loxycarbonyl (alloc,

-C(0)0-CT-I=CH 2 ), and /-butoxylmetliyl;

X is halogen, OH, aikylthio, arylthio, sulfoxide (R'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosyiate, or triflate), OC(=NH)CCi 3 , OP0 3 H, OPO 3 R' or

OCH2CH2CH 2 CH= : CH 2 , wherein R' is (Ci-C4)alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to pro vide a compound of formula XVIII),

wherein Ri and R2 are defined as hereinabove; and

(b) removing the protec ting groups R; and R 2 of the compound of formula (XVI11) to provide the compound of formula (XVI).

[8028] In another aspect, the present invention provides to a process for preparing a compound of formula (XIX) (i.e., Rebaudioside O, RO):

comprising:

(a) reacting the compound of formula (II),

wherein each R 2 is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (d-C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoToacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyf protecting groups (e.g., triniethylsilyi, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyL diethylisopropylsilyl, dimetiiyithexvlsilyi, i-butyldimefhylsiiyL i-butyldiphenylsilyl, tribenzylsiiyl, tri- »-xylylsilyl, triphenyfsilyl, dipheiiylmethylsilyl, di-/-butylmethy]silyl, trisitrimethylsilynsilyi, (2-hydToxystyryl)dimethylsilyI, 2-hydroxys1yiyl)disopropyfsilyl, / ■■ butyimeihoxyphenylsilyi, i-butoxydiphenylsilyl), allyloxvcarbonyi (alloc,

· ( ' · ( )) ( ) ■( I ! >c: ί 1 and i-butoxylmethyl;

with a compound of formula (XX),

wherein each Rj is independently a protecting group selected from benzyl, j-methoxybenzyl fPMB), benzyloxy methyl, /?-methoxybenzy]oxy methyl, (C j -C 4 )aU yl-aeyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., trimethylsilyl, triethylsilyl, frisopropylsilyJ, dimethylisopropylsilyl, diethylisopropyisilyl, dimethyiihexylsilyl, i-butyldimethylsiiyi, i-butyldiphenylsiiyL tribenzylsilyi, tri- ?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsilyl)sily], (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxyearbonyl (alloc,

·(·((.) !( }·(·! ! (Ί Ι . ι. and i-butoxylniethyl;

X is halogen, OH, afkylthio, arylthio, sulfoxide (R'S(=0)-), sultone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triflate), GO Μ ΠΓί ' ί .. OPO 3 H, OPO 3 R' or

OCH2CH2CH2CH-CH2, wherein R' is (Cj-C4)alkyl or aryl, and the anonieric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XXI),

wherein Rj and R 2 are defined as hereinabove; and (b) removing the protecting groups Ri and R 2 of the compound of formula (XXI) to provide the compound of formula (XIX).

Brief Description of the Drawings

[0021] Figure 1 depicts ¾- MR for compound ia'.

[0022] Figure 2 depicts H-NMR for compound acetylated

[0023] Figure 3 depicts H-NMR for compound acetylated

[0024] Figure 4 depicts 1 FI-NMR for compound RD.

[0025] Figure 5 depicts H-NMR for compound Xia.

[0026] Figure 6 depicts 1 H-NMR for compound RM.

Detailed Description of the invention

In one aspect, the present invention provides a process for preparing a compound of formula (IV):

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

(VII) wherein each R? is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)aIkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and tfifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxytnefhyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsifyl, trisopropyisilyl, dimethyiisopropylsiiyf, diethyiisopropylsiJyl, dinietliylthexylsiiyl, ί-butyldimet ylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri- ?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsiiyl)silyl, (2-hydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 3 , i-butoxydiphenyi si lyl ), al lyl oxycarbony 1 (al loc,

•C ' i O M i l ( ' Π '). and i-butoxylniethyi;

to provide a compound of

(Π)

wherein each R 2 is defined as hereinabo^

(b) reacting the compound of formula (11) with a compound of formula (1),

wherein each Rj is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (C] -C4)alkyl-aeyl (e.g., acetyl), halogen substituted (C;-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsilyl, triethylsiiyl, trisopropyisilyl, dimethylisopropylsilyl, diethylisopropyisilyl, dimetliyithexylsilyl, /-butjddimethylsiiyf, i-butyldiphenylsilyl, tribenzylsilyl, tri-o-xylyisilyi, triphenyisilyl, diphenylmethylsilyl, di-i-butylmethylsilyi, tris (trim eth y Isily I) si ly 1 , (2-hydroxystyryl)dimethylsiiyl, 2-hydroxystyryT)disopropyisifyl, i-buty1methoxyphenylsi1yl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and i-butoxylmethyl:

X is halogen, OH, alkylthio, arylthio, sulfoxide ( 'S(-0)-), sulfone (R'S(-0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , OP0 3 H, OPO3R' or

OCH 2 CH 2 CH 2 CH=CH 2 , wherein R' is (C; -C4)aikyl or aryi, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula Hi),

wherein Ri and R2 are defined as hereinabove;

(c) removing the protecting groups R; and R 2 of the compound of formula (HI) to provide the compound of formula (IV).

[8028] in another aspect, the present invention provides a process of preparing a compound of formula (X):

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each R 2 is independently a protecting group selected from benzyl, /?-methoxybenzyl (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (Ci-C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C^jalkyi-acyl (e.g., chloroaceryl, dichloroacetyl, trichloroacetyl, and irifluoroacetyl), aryl-acyl (e.g., benzoyl), irimeihyisilylethoxymethyl (SEM), siiyl protecting groups (e.g., trimethyisilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropyf si lyi, dimethyithexylsilyl, i-butyldimethy lsiiyl, t-bufy Idipheny Isifyl, iribenzylsilyl, iri-p-xyiyisiiyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyi)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl > /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-Ci O iO-CU .( Ή ( " > [ . ;. and i-butoxyimethyl;

to pro vide a compound of formula (II),

wherein each R? is defined as hereinabove;

(b) reacting the compound of fonnula (II) with a compound of formula (XI),

wherein each Rj is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, /j-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)aikyl-acy] (e.g., chloroacetyl, dichioroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylet oxymet y] (SEM), silyl protecting groups (e.g., rrimeihyisilyl, triethylsiivl, trisopropyisilyi, dime thy iisopropylsiiyl, diethylisopropyisilyl, dimethyhhexylsilyl, /-butyldiinethylsiiyL /-butyldiphenylsiiyl tribenzylsilyi, tri-/?-xylyisilyI, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsilyl)sily], (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butyhnethoxyphenylsilyl, /-butoxydiphenylsiiyl), all loxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and /-butoxylmethyl;

X is halogen, OH, aikylthio, arylthio, sulfoxide ( 'S(=0)-), sulfone (R , S(=0) 2 -) ! sulfonate (e.g., mesylate, tosyiate, or triflate), ()( ' ( N i i ii ' Ci : . OP0 3 H, GPO 3 R' or

OC¾C¾CH 2 CH ¾, wherein R' is (Ci-C4)alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to pro vide a compound of fo

wherein Ri and R 2 are defined as hereinabove;

(c) removing the protecting groups Ri and R 2 of the compound of formula (III) to provide the compound of formula (X).

[8029] In another aspect, the present invention provides a process for preparing a compound of formula (ΧΙΠ): (XIII)

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each R2 is independently a protecting group selected from benzyl, j-methoxybenzyl (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (C j -C 4 )aU yl-aeyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroaeetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., trimethylsiiyi, triethylsilyl, trisopropylsilyl, dimet ylisopropylsilyl, diethylisopropyisilyl, dimethvlihexylsilyl, i-butyldimetliylsilyi, i-butykliphenylsilyL iribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyL tris(trimethylsilyf)silyl, (2-hydroxystyryl)dimetliylsifyl, 2-hydroxystyryi)disopropylsifyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsiJyl), allyloxycarbonyJ (alloc,

-C{O sO -O U ' H CM.. ), and t-butoxylmethyl;

to provide a compound of formula (ΐΐ),

wherein each R 2 is defined as hereinabove:

(b) reacting the compoun und of formula (XIV), IV)

wherein each Rj is independently a protecting group selected from benzyl, /j-methoxybenzyl (PMB), benzyioxy methyl, / methoxybenzyloxy methyl, (Ci -C4)alkyl-aeyi (e.g., acetyl), halogen substituted (Ci -C4)aikyl-acy] (e.g., chloroacetyl, dichJoroacetyf, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethy] (SEM), silyl protecting groups (e.g., rrimethyisilyl, triethylsiivl, trisopropyisilyl, dime thy iisopropylsiiyl, diethylisopropyisilyl, dimethylthexylsilyl, i-butyldimethylsilyl, /-butyldiphenylsiiyl tribenzylsilyi, tri- ?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, rris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsiiyi, 2-hydroxystyryl)disopropylsiIyl, i-butyhnethoxyphenylsilyl, /-butoxydipheny silyl), all loxycarbonyl (alloc,

-( {ϋΚΚ ' ί ί 'Π ί CI I , !, and /-butoxylmethyl;

X is halogen, OH, aikylthio, arylthio, sulfoxide (R'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triilate), OC(=NH)CCl 3 , OPO3H, OPO3R' or

OCH 2 CH 2 CH 2 CH= : CH 2:< wherein R' is (C|-C'4)aikyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to pro vide a compound of formula (X V), (XV)

wherein Ri and R 2 are defined as hereinabove;

(c) removing the protecting groups R; and R 2 of the compound of formula (III) to provide the compound of formula (XIII).

[0030] In another aspect, the present invention provides a process for preparing a compound of formula (XVT)

comprising:

(a) selectively hydrolyzing a compound of formula (VTI),

wherein each R 2 is independently a protecting group selected from benzyl, Hrnethoxybenzyl (PMB), benzyloxy methyl, /?-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxvinethyl (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsiiyl, trisopropyisiiyl, dimethyiisopropylsiiyL diethylisopropylsilyl, dimethylthexylsilyi, i-butyidimethylsilyi, i-but ddiphenylsilyl, tribenzyisiiyl, tri- ?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmetbylsilyl, tris(trimethylsilyi)silyl, (2 iydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropylsiiyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and /-hutoxyimethyl;

to provide a compound of for

(11)

wherein each R 2 is defined as hereinabove;

(b) reacting the compound of formula (II) with a compound of formula (XVII),

wherein each ¾ is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, j-methoxybenzyloxy methyl, (Ci -C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyJ (e.g., chloroacetyl, diehloroacetyl, trichloroacetyi, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsiiyl, trisopropylsilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyi, i-butyidimethylsilyl, i-butyldiphenylsilyl, tribenzyisiiyl, tri- ?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i~butylmethyisilyl, tr i s ( tr ime thy 1 si ly ί ) s ily 1, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, ί-butoxydiphenylsilyi), allyloxycarbonyl (alloc,

-( i ())0-(] | .(l ! ( " ! (>}. and i-butoxylmethyl;

X is halogen, OH, aikylthio, aryithio, sulfoxide (R'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , OP0 3 H, OPO3R' or OCH 2 CH 2 CH 2 CH=CH¾ wherein R' is (Ci-C4)alkyl or and, and the anomeric carbon attached with X can be eiiher or β coniiguraiion;

io provide a compound of formula (XVIII),

(XVIII)

wherein Ri and R 2 are defined as hereinabove;

(c) removing the protecting groups Rj and R? of the compound of formula (XVIII) to provide the compound of formula (XVI).

[8(531] In another aspect, the present invention provides a process for preparing a compound of formula (XIX

comprising:

(a) selectively hydrolyzing a compound of formula (VII),

wherein each R? is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)aIkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethylsiiyl, triethylsifyl, trisopropylsilyl, dimethylisopropylsilyf, diethyJisopropylsiJyl, dinietliylthexylsiiyl, i-butyldimet ylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsiiyl)si]yl, (2-bydToxystyryl)dimethylsilyi, 2-hydroxys1yiyl)disopropyfsilyl, i-butyim etb oxypheny is i ly 1 , i-butoxydipheny Isi lyl ), al lyl oxycarbony 1 (al loc,

•C ' i O M i i ( I I .). and i-butoxyrmethyl;

to provide a compound of

(Π)

wherein each R 2 is defined as hereinabcn

(b) reacting the compound of formula (11) with a compound of formula (XX),

wherein each Ri is independently a protecting group selected from benzyl, />-methoxybenzy3 (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), siiyf protecting groups (e.g., trimethylsiiyl, triethylsiiyl, trisopropylsilyl, dimethyiisopropylsiiyL diethylisopropylsilyl, dimethylthexylsilyi, i-butyidimethylsilyi, i-but ddiphersylsilyl, trihenzyisilyl, tri- ?-xylylsilyl, triphenylsilyl, diphenyhnethylsilyi, di-i-butylmethylsilyl, rris(trimethylsilyi)silyl, (2-hydroxystyryl)dinietliyls " iiyl, 2-hydroxystyTyl)disopropylsiiyl, i-butylmethoxyphenylsilyl, /-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-C(0)0-CH 2 CH=CH 2 ), and /-hutoxylmemy!;

X is halogen, OH, alkylthio, arylthio, sulfoxide ( 'S(=0)-), sulfone (R , S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or inflate), OC(=NH)CCl 3 , OP0 3 H, OPO3R' or

OC¾CH 2 CH 2 CH=CH 2 , wherein R' is (Cj-C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to pro vide a compound of formula (XXI),

wherein Rj and R 2 are defined as hereinabove;

(c) removing the protecting groups Ri and R2 of the compound of formula (III) to provide the compound of formula (XIX).

[0032] In certain embodiments, in step (b), the compound of formula (II) is reacted with the X-substituted intermediate without the use of Ag 2 COi.

[8033] In certain embodiments, each Ri is independently (Ci -C 4 )alkyl-acyl (i.e.,

(Ci -C 4 )aJkyl-C(==0)-) or phenyl. In certain other embodiments, each R 2 is independently or phenyl.

[8034] In certain embodiments, each Ri is independently acetyl (CHjC(-0)-). In certain other embodiments, each R 2 is independently acetyl (CHbC(=0)-). [0035] In a further aspect, the present invention provides to a process for preparing a compound of formula (X) (i.e., ebaudioside M, RM :

comprising:

(a) reacting the comp

(II)

wherein each R? is independently a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyloxy methyl, j-methoxybenzyloxy methyl, (Ci -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyI-acyl (e.g., chioroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), triniethylsilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropyisilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyi, i-butyidimethylsilyi, ^butyldiphenylsilyl, trihenzylsiiyl, tri- ?-xylyIsilyI, triphenylsilyl, diphenylmet ylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsily], i-butoxydiphenylsilyi), allyloxycarbonyl (alloc,

-( i ())0-(] | .(l ! C! i >). and i-butoxyim ethyl;

with a compound of formula (XI),

wherein each ] is independenily a protecting group selected from benzyl, p-methoxybenzyl (PMB), benzyioxy methyl, ?-methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyJ (e.g., chioroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), arvl-acyl (e.g., benzoyl), trimethyisilyiethoxymethyi (SEM), siiyi protecting groups (e.g., trimethyisilyl, triethylsilyl, trisopropyisilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyi, /-butyklimethylsilyf, i-butyldiphenylsiiyl, tribenzylsiiyl, tri- ?-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)d " isopropylsilyl, i-butylmethoxyplienylsily], i-butoxydiphenylsilyi), allyioxycarbonyl (alloc,

-C(0)0-CH=CH 2 ), and i-butoxylmethyl;

X is halogen, OH, aikylthio, aryiihio, sulfoxide (R'S(=0)-), sulfone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triilate), OC(=NH)CCl 3 , OP0 3 H, OPO3R' or

OCH2CH2CH 2 CH=CH 2 , wherein R' is (Cj-C4)alkyl or arvl, and the anomenc carbon attached with X can be either a or β configuration;

to provide a compound of formula (XII),

wherein R 1 and R 2 are defined as hereinabove; and

(b) removing the protecting groups Ri and R 2 of the compound of formula (XII) to provide the compound of formula (X). [8036] Irs another aspect, the present invention provides to a process for preparing a compound of formula (XIII) (i.e., Rebaudioside N, RN):

comprising:

(a) reacting the compound of formula (II),

wherein each R? is independemly a protecting group selected from benzyl, ?-methoxybenzyi (PMB), benzyloxy methyl, / methoxybenzyloxy methyl, (Ci -C4)alkyl-acyl (e.g., acetyl), halogen substituted (e.g., chioroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyi protecting groups (e.g., trimethyisilyl, triethylsiiyl, trisopropyisilyl, dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyi, /-butj dimethylsilyf, i-butyldiphenylsiiyl, tribenzylsiiyl, tri- ?-xylylsilyl, tripheny silyl, diphenylmethylsilyl, di-i-butylmethylsilyl, tris(trimethylsiiyi)silyl, (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsily], /-butoxydiphenyls ly]), allyloxycarbonyl (alloc,

-( i ())0-(] | .(l ! C! i >). and i-butoxylm ethyl;

with a compound of formula (XIV),

wherein each Ri is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, / nethoxybenzyloxy methyl, (d-C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), siiyf protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsiiyl, dimethylisopropylsilyL

diethylisopropylsilyl, dimetiiyithexvlsilyi, i-butyldimefhylsiiyL i-butyldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-i-butylmethylsilyl, trisitrimethylsilynsilyi, (2-bydroxystyryl)dimethylsilyI, 2~hydroxystyry!)di8opropyfsiiyl, / ■■ butyimeihoxyphenylsilyi, i-butoxydiphenylsilyl), allyloxvcarbonyi (alloc,

-O <))<)-< 1 1 Cl ! . and /-butoxylmethyl;

X is halogen, OH, aikylthio, aryithio, sulfoxide (R.'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, iosylate, or triflaie), OC(=NH)CCU, OPO 3 H, OPO 3 R' or

QCH 2 CH 2 C¾CH=C3¾, wherein R' is (d -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XV),

wherein Rj and R. 2 are defined as hereinabove; and

(b) removing the protecting groups j and R? of the compound of formula (XV) to provide the compound of formula (XIII).

[0037] In another aspect, the present invention provides to a process for preparing a compound of formula (XVI) (i.e., Rebaudioside T, RI):

comprising:

(a) reacting the compoun

(Π)

wherein each R 2 is independently a protecting group selected fro benzyl, /j-methoxybenzyl (PMB), benzyioxy methyl, j-methoxybenzyloxy methyl, (C] -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protectmg groups (e.g., rrimeihyisilyl, triethylsiivl, trisopropyisilyl, dime thy lisopropylsilyl, diethylisopropyisilyl, dimethylthexylsilyl, /-butyldimethylsiiyi, /-butyldiphenylsiiyl tribenzylsilyl, tri- ?-xylyisilyI, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsilyl)si!yl, (2-hydroxystyryl)dimethylsiIyl, 2-hydroxys†yryl)disopropylsilyl, i-butylmethoxyphenylsilyl, /-butoxydiphenyfsilyl), allyloxycarbonyl (alloc,

-C(0 )0-CH 2 CH=CH 2 ), and t-butoxylmethyl;

with a compound of formula (XVTI), (XVII) wherein each Rj is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyi, dichloroacetyi, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), siiyi protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyf, diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-/?-xylylsilyl, triphenyisilyl, diphenylmethylsilyl, di-/-butylmethylsilyi, tris(trimethylsilyl)si]yl, (2-bydroxystyryl)dimethylsilyi, 2-hydroxystyryl)disopropyisilyl, i-butyim eth oxypheny Is i ly 1 , i-butoxydiphenyl si lyl ), al lyl oxycarbony 1 (al loc,

•C ' i O M i l ( ' Π '). and i-butoxylmethyi;

X is halogen, OH, alk lthio, arylthio, sulfoxide (R.'S(=0)-), sulfone (R'S(=0) 2 -), sulfonate (e.g., mesylate, tosylate, or triflate), OC(=NH)CCl 3 , GPChH, OPO3R' or

OCH 2 CH 2 CH 2 CH=CH2, wherein R' is (Ci -C 4 )alkyl or aryl, and the anomeric carbon attached with X can be either a or β configuration;

to provide a compound of formula ( X V H i }.

(XVIII) wherein Ri and R 2 are defined as hereinabove; and

(b) removing the protecting groups Rj and R? of the compound of formula (XVIII) to provide the compound of formula (XVI).

[8038 In another aspect, the present invention provides to a process for preparing a compound of formula (XIX) (i.e., Rebaudioside O, RO):

comprising:

(a) reacting the compound of formula (II),

wherein each R 2 is independently a protecting group selected from benzyl, -methoxybenzyJ (PMB), benzyloxy methyl, ?-methoxybenzyloxy methyl, (d-C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Cj-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoToacetyl), aryl-acyl (e.g., benzoyl), trimethyisilylethoxymethyl (SEM), silyf protecting groups (e.g., triniethylsilyi, triethylsilyl, trisopropylsilyl, dimethylisopropylsilyL diethylisopropylsilyl, dimetiiyithexvlsilyi, i-butyldimefhylsiiyL i-butyldiphenylsilyl, tribenzylsiiyl, tri- »-xylylsilyl, triphenyfsilyl, dipheiiylmethylsilyl, di-/-butylmethy]silyl, trisitrimethylsilynsilyi, (2-hydToxystyryl)dimethylsilyI, 2-hydroxys1yiyl)disopropyfsilyl, / ■■ butyimeihoxyphenylsilyi, i-butoxydiphenylsilyl), allyloxvcarbonyi (alloc,

· ( ' · ( )) ( ) ■( I ! >c: ί 1 and i-butoxylmethyl;

with a compound of formula (XX),

wherein each Rj is independently a protecting group selected from benzyl, j-methoxybenzyl fPMB), benzyloxy methyl, /?-methoxybenzy]oxy methyl, (C j -C 4 )aU yl-aeyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyi, trichloroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sifyl protecting groups (e.g., trimethylsilyl, triethylsilyl, frisopropylsilyJ, dimethylisopropylsilyl, diethylisopropyisilyl, dimethyiihexylsilyl, i-butyldimethylsiiyi, i-butyldiphenylsiiyL tribenzylsilyi, tri- ?-xylyisilyi, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethylsilyf, tris(trimethylsilyl)sily], (2-hydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

·(·((.) !( }·(·! ! (Ί Ι . ι. and i-butoxylniethyl;

X is halogen, OH, afkylthio, arylthio, sulfoxide (R'S(=0)-), sultone (R'S(=0)2-), sulfonate (e.g., mesylate, tosylate, or triflate), GO Μ ΠΓί ' ί .. OPO 3 H, OPO 3 R' or

OCH2CH2CH2CH-CH2, wherein R' is (Cj-C4)alkyl or aryl, and the anonieric carbon attached with X can be either a or β configuration;

to provide a compound of formula (XXI),

wherein Rj and R 2 are defined as hereinabove; and (b) removing the protecting groups Ri and R 2 of the compound of formula (XXI) to provide the compound of formula (XIX).

[8(539] In certain embodiments, in step (a), the compound of formula (II) is reacted with the X-substituted intermediate without the use of AgjCO

[0040] In certain embodiments, each R i is independently (Ci -C^jalkyl-acyl (i.e., (Ci~C4)alkyl~C(=0)~) or phenyl. In certain other embodiments, each R 2 is independently (Ci -C 4 )aikyl-aeyi (i.e., { ( ' · ( .. !asks i-< i ())· ) or phenyl.

[8041] In certain embodiments, each R] is independently acetyl (Ο¾(Γ'(=0)-). ΐη certain other embodiments, each R 2 is independently acetyl (CH3C(=0)-).

[8042] In certain embodiments, the compound of formula (VII) is prepared by:

(a) hydrolyzing a com ound of formula (VIII),

to provide a compound of formula (IX),

(b) protecting the OH groups of the compound of formula (IX) to provide the compound of formula ( VII),

wherein each R 2 is independently a protecting group selected from benzyl, /?-methoxybenzyl (PMB), benzyloxy methyl, -methoxybenzyloxy methyl, (Ci-C 4 )alkyl-acyl (e.g., acetyl), halogen substituted (Ci -C^jalkyi-acyl (e.g., chloroacetyl, dichloroacetyl, trichioroaeetyl, and rrifluoroacetyl), aryl-acyl (e.g., benzoyl), irimeihyisilylethoxymethyl (SEM), siiyl protecting groups (e.g., trimethyisilyl, triethylsilyl, trisopropylsilyl, dimetihylisopropylsilyi, diethylisopropyf si lyl, dimethylthexylsilyl, i-butyldimethy lsiiyl, t-bufy ldipheny Isifyl, iribenzylsilyl, iri-p-xyiyisiryi, triphenyisilyl, diphenylniethylsilyl, di-i-butylmethylsilyl, tris(trimethylsilyi)silyl, (2-hydroxystyryl)dimethylsilyl > 2-hydroxystyryl)disopropylsilyl > /-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

' ί ί) )ί)-Π i.'O ! ( " ! [ . ;. and f-butoxylmethyl,

[8043] In certain embodiments, each 3¾ is independently (CrC^alkyl-acyl (i.e.,

(C i -C 4 )alkyl-C(=0)-) or phenyl. In certain other embodiments, each R? is independently acetyl (CH 3 C(=0)-).

[8044] In one aspect, the present invention provides a compound of formula (IV) prepared by the processes as described hereinabove.

[0045] In another aspect, the present invention provides a process of preparing a compound of formula (III),

(III) comprising reacting a compound of formula (II),

wherein each R? is independently a protecting group selected from benzyl, j P-methoxybenzyl (PMB), benzyioxy methyl, ?-methoxybenzyloxy methyl, (Cj-C4)alkyi-acyl (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chioroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethyfsilyl, trisopropylsilyl, dimethylisopropyisilyl, diethyiisopropylsiivl, dimethylmexyisilyl, /-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tris(trimethylsilyl)sifyl, (2-hydroxystyTyl)dimethylsilyl,

'2-bydroxystyryj.)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenyisilyl), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH2), and i-butoxylmethyl;

with a compound of formula (la),

wherein each Ri is independently a protecting group selected from benzyl,

/?-methoxybenzyl (PMB), benzvloxy methyl, ?-methoxybenzyloxy methyl, (Ci-C4)alkyl-acyi (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chioroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethyIsilyIethoxym.ethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, trieihyisilyl, trisopropylsilyl, dimethylisopropyisilyl, diethyiisopropylsiivl, dimethyltiiexyisilyl, f-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri- >-xylylsiIyl, triphenylsilyl, diphenylmethylsilyl, di-i-buiylmeihylsilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl, 2-bydroxystyryl)disopropylsilyl, i-butylmethoxypheny3silyl, i-butoxydiphenylsil 3), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxylmethyl; and the anomeric carbon attached with Br can be either a or β configuration;

to provide a compound of formula (III) without the use of Ag 2 C0 3 .

[8046; In certain embodiments, the anomeric carbon attached with Br is a configuration.

[8(547] In certain embodiments, the compound of formula (II) is reacted with the compound of formula (la) in the presence of a phase transferring reagent and an inorganic base.

[8(548] In certain embodiments, the phase transferring reagent is TBAB, TBAC, TBAI, or TEBAC. In certain other embodiments, the inorganic base is KHC(¾, K 2 C0 3 , K 3 PO4, or KH2PO4.

[8849] In one aspect, the present invention provides a compound of formula (HI) prepared by the processes as described hereinabove.

[8858] In another aspect, the present invention provides a process of preparing a compound of formula (ITT),

comprising reacting a comp

(Π) wherein each R? is independently a protecting group selected from benzyl, j P-methoxybenzyl (PMB), benzyioxy methyl, ?-methoxybenzyloxy methyl, (Ci-d)alkyi-acyl (e.g., acetyl), halogen substituted (e.g., chloroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethyf silyl, trisopropylsilyl, diniethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyl, i-butyklimethylsilyl,

1- butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethyisilyl, di-i-butylmethyisilyl, tiis(trimethylsilyl)sifyl, (2-hydroxystyTyl)dimethylsilyl,

2- bydroxystyryj.)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxylmethyl;

with a compound of formula (lb),

wherein each Ri is independently a protecting group from benzyl, -methoxybenzyl (PMB ), benzyioxy methyl, /?-methoxybenzyloxy methyl, (C 1 -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C )aikyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, friethylsilyl, trisopropylsilyl, dimethyiisopropylsiiyL

diethylisopropylsilyl, dimethylthexylsilyl, i-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri- »-xylylsilyl, triphenylsilyl, diphenylmethyisilyl, di-i-butylmethyisilyl, tris(trimethylsilyl)si]yl, (2-bydroxystyryl)dimethylsilyl, 2-hydroxystyryl)disopropylsilyl, i-butylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc,

-Ci O iO-i i I■( ' ! I ( I i · ;. and i-butoxylmethyl, and the anomeric carbon attached with S can be either or β configuration;

to provide a compound of formula (III). 8051] In certain embodiments, the anomeric carbon attached with Br is a configuration.

[8052] In certain embodiments, the compound of formula (II) is reacted with the compound of formula (lb) in the presence of NIS (N-iodosuccmimide) and an acid. In certain embodiments, the acid is a Lewis acid. In certain other embodiments, the acid is a Lewis acid selected from TBSOTf (CFiiSC SiMey -Bu), TMSOTf (irifluoromeihanesulfonic acid irimethyisilylester), TfOH, and IDCP (iodonium dicollidine perchlorate).

[0053] In one aspect, the present invention provides a compound of formula (III) prepared by the processes as described hereinabove.

[8054] In yet another aspect, the present invention provides a process of preparing a compound of formula (III),

comprising reacting a comp

(Π)

wherein each R. 2 independently a protecting group selected from benzyl,

jP-methoxybenzyl (PMB), benzyloxy methyl, >-metb.oxybexizy1oxy methyl, (Cj-C- alkyi-acyi (e.g., acetyl), halogen substituted (Ci-C4)alkyl-acyl (e.g., chloroacetyl, dichloroacetyl, trichforoacetyl, and trif!uoroacetyl), aryl-acyi (e.g., benzoyl), trimethyfsilylethoxymethyl (SEM), siiyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsiiyl, dimethylisopropyisilyl, diethylisopropylsilyi, dimethylthexylsilyl, /-butyldimethylsilyl, i-butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethyisilyl, di-i-butylmethylsilyl, tris(trimethylsiiy1)silyl, (2-hydroxystyryl)dimethylsi]yl, 2-bydroxystyryl)disopropylsilyl, ί-butylmeth xypheiiylsilyl, i-butoxydiphenylsilyi), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxylniethyl;

with a compound of formula (Id),

wherein each Ri is independently a protecting group selected from benzyl, j P-methoxybenzyl (PMB), benzyloxy methyl, ?~metboxybenz) oxy methyl, (Cj-C4)alkyi-acy (e.g., acetyl), halogen substituted (e.g., chioroaeetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimethylsilylethoxymethyl (SEM), sily] protecting groups (e.g., trimethyisilyl, triethyfsilyl, trisopropylsilyl, dimethylisopropylsilyl, diethyiisopropylsiiyl, dimethylthexylsilyl, /-butyldimethylsilyl,

1- butyldiphenylsilyl, tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl, di-i-butylmethyisilyl, tris(trimethylsily])sifyl, (2-hydroxystyryl)dimethylsi]yl,

2- bydroxystyryj.)disopropylsilyl, i-burylmethoxyphenylsilyl, i-butoxydiphenylsilyl), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxyimethyl; and ihe anomeric carbon attached with OH can be either a or β configuration;

to provide the compound of formula (HI).

[8055] In certain embodiments, the anomeric carbon attached with Br is a configuration.

[8056] The certain embodiments, the compound of formula (II) is reacted with the compound of formula (Id) in the presence of a Lewis acid. In certain other embodiments, the acid is a Lewis acid selected from TBSOTf (CF 3 S0 3 SiMe 2 t-Bu), TMSOTf

(trifluoromethanesulfomc acid irinieihyisiiyiester), TfOH, BF3:Et 2 0, and IDCP (iodo ium dicolfidine perchlorate). In yet other embodiments, the Lewis acid is TBSOTf

( Ί ;SO .Si:vk: ; ;--Bii L TMSOTf, or TfOH.

[8(557] In one aspect, the present invention provides a compound of formula (III) prepared by the processes as described hereinabove.

[8058] The certain embodiments, the protecting groups Rj and R. 2 of the compound of formula (III) as described hereinabove can be removed via, e.g., hydrolysis, to provide a compound of formula (IV),

In certain embodiments, the compound of formula (II),

is prepared by selectively hydrolyzing a compound of formula (VII),

wherein each R. 2 is independently a protecting group selected from benzyl,

/?-methoxybenzyl (PMB), benzvloxy methyl, ?-methoxybenzyloxy methyl, (Ci-C alkyl-acyi (e.g., acetyl), halogen substituted (CrC 4 )alkyi-acyl (e.g., chloroacetyl, dichloroacetyl, trichloroacetyl, and trifluoroacetyl), aryi-aeyl (e.g., benzoyl), rrimethyIsilyIethoxym.eth.yl (SEM), silyl protecting groups (e.g., trimethylsilyl, trieihyisilyl, trisopropylsilyl, dimethylisopropylsilyl, diethyiisopropylsiiyl, dimethylthexylsilyl, f-butyldimethylsilyl, i-butyld phenylsilyl, tribenzylsilyl, tri- »-xylylsiIyl, triplienylsilyl, diphenylmetliylsilyl, di-/-buiylmeihyisilyL tris(trimethylsilyl)siiyl, (2-hydroxystyryl)dimethylsilyl, 2-bydroxystyryl)disopropylsilyl, i-butylmethoxypheny3silyl, i-butoxydiphenylsil 3), allyloxycarbonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxylniethyl.

[0060] In certain embodiments, each R 2 is independently (Cj-C4)alkyl-a.cyl (i.e., (C] -C-4)alkyl-C(= : 0)-) or phenyl In certain other embodiments, each 2 is independently acetyl (CH 3 C( ))-).

[8(561] In certain embo (VII),

II)

is prepared by:

(a) hydrolyzing a compound of formula (VIII),

to provide a compound of formula IX),

(b) protecting the OH groups of the compound of formula (IX) to provide the compound of formula (VII),

wherein each 2 is independently a protecting group selected from benzyl,

>-methoxybenzyl (PMB), benzyloxy methyl, j?-methoxyhenzyloxy methyl, (Ci -C4)alkyl-acyl (e.g., acetyl), halogen substituted (Ci-C^alkyi-aeyl (e.g., chloroacetyl, dichloroacetyl, trichioroacetyl, and trifluoroacetyl), aryl-acyl (e.g., benzoyl), trimeihyisilylemoxymethyl (SEM), silyl protecting groups (e.g., trimethylsilyl, triethylsilyl, trisopropylsilyl,

dimethylisopropylsilyl, diethylisopropylsilyl, dimethylthexylsilyl, /-butyldimethylsilyl,

1- butyldiphenylsilyl, rribenzylsilyl, iri-p-xyiylsiiyl, triphenylsilyl, diphenylmethylsilyl, di-/-butylmethyisilyl, tris(trimethylsilyl)silyl, (2-hydroxystyryl)dimethylsilyl,

2- hydroxystyryl)disopropy1silyl, i-buty3methox>phenylsilyl, i-butoxydiphenyisilyl), allyloxyearhonyl (alloc, -C(0)0-CH 2 CH=CH 2 ), and i-butoxyl methyl.

[8062] In certain embodiments, each R 2 is independently

(C i -C 4 )aJkyl-C(==0)-) or phenyl. In certain other embodiments, each R? is independently acetyl (CH 3 C(=0)-).

[8063] In a further aspect, the present invention provides a compound of Examples 1-8 prepared by the processes as described therein.

Methods of Preparation

[8064] In the following schemes, the protecting groups Ri and R 2 are defined as hereinabove. Other suitable OH protecting groups can be found in Greene and Wuts, Protective Groups in Organic Synthesis, 3 ra Ed., 1999, which is incorporated by reference in its entirety.

[8(565] As illustrated in Scheme 2, the compound of Formula (lb) is prepared by reacting the compound of Formula (la) with toluenethiol (TolSH). The compound of Formula (Ic) is prepared by al-catalyzed hydrolysis of the compound of Formula (la). The compound of formula (id) is obtained by condensation of the compound of Formula (Ic) with

trichloroacetonitrile in the presence of DBU. The compound of Formula (la) (wherein Rj = acetyl) is a derivative of sophorose and can be prepared from Stevioside (ST) by a literature procedure (J.A. C.S. 78, 4709, 1 57).

Scheme 2

!c ili

As shown in Scheme 3, the compound of formula (TIT) can be obtained by reacting the compound of formula (II) with the compound of formula (la) in the presence of a phase transfer reagent and an inorganic base. Advantageously, this step does not require the use of Ag 2 C0 3 , a potentially toxic heavy metal. The phase transferring reagent includes, but is not limited to, TBAB, TBAC, TBAI, or TEBAC; and the inorganic base is KHC0 3 , K2CO3, K3PO4, or KH2PO4. The inorganic base includes, but is not limited to, an alkaline salt of carbonate, phosphate or its buffer solution, e.g., KHCO 3 , K2CO 3 , K 3 PO4, or KH2PO4.

[8(567] Alternatively, the compound of formula (111) can be obtained by reacting the compound of formula (II) with the compound of formula (lb) in the presence of S and an acid, such as a Lewis acid. The Lewis acid includes, but is not limited to, TBSOTf (CF 3 S0 3 SiMe 2 i-Bu), TMSOTf (trifluoromethanesuifonic acid trimethylsilyi ester), TfOH, BF 3 :Et 2 Q, and IDCP (iodonium dicollidine perchlorate). Furthermore, the compound of formula (III) can be obtained by reacting the compound of formula (Π) with the compound of formula (Id) in the presence of a Lewis acid such as TBSOTf (CF 3 S0 3 SiMe 2 t-Bu), TMSOTf, or TfOH.

According to Scheme 4, the compound of Formula (II) is obtained by selective hydrolysis of the compound of Formula (VII). In certain embodiments, selective hydrolysis can be achieved by reacting the compound of Formula (VII) with an acid. Non-limiting examples of the acid include HCl, H 3 P0 4 , NaH 2 P0 4 , ΚΗ 2 Ρ0 4 , BF 3 .Ei 2 0, and HBF 4 .

Scheme 4

As shown in Scheme 5, the compound of Formida (VII) is prepared by hy droly sis of the compound of Formula (VIII) (i.e., RA) to afford the compound of Formula (IX), followed by protecting the OH groups of the compound of Formula (IX). In certain embodiments, the conversion from the compound of formula (IX) to the compound of formula (VII) and then to the compound of formula (II) (in Scheme 4) can be done in one pot synthesis. Scheme 5

[8(578] According to Scheme 6, the compound of formula (IV) (i.e., RD) is obtained by removing the protecting groups of R; and R 2 of the compound of Formula (III). In certain embodiments, the removal is achieved by hydrolysis. Purification of final product RD can be performed by general purification methods, such as extraction, washing, crystallization, column chromatography, and re-crystallization. In certain embodiments, alcohol/water is used for the re-crystallization. In certain other embodiments, ethyl alcohol/water is used for the re-crystallization.

Scheme 6

[8071] As illustrated in Scheme 7, the compound of formula IX (RA) is protected to giv( the compound of formula (XXII), which is selectively hydrolyzed to give the compound of formula (XXIII). Treatment of compound of fomiula (XXIII) with an acid such as hydrogen bromide affords the compound of formula (XI) which further reacts with the compound of formula (II) to yield the compound of formula (XII), followed by subsequent hydrolysis to provide the compound of formula (X) (RM).

Scheme 7

[8(572] The synthesis of the compound of formula (XIII) (RN) is shown in Scheme 8. Hydrolysis of the compound of formula (XXIV) (Rebaudioside C, RC) gives the compound of formula (XXV) which is protected and followed by selective hydrolysis to yield the compound of formula (XXVI). Conversion of the compound of formula (XXVI) by treataient of an acid (such as HBr) affords the compound of formula (XIV) which further reacts with the compound of formula (II) to provide the compound of formula (XV), Deprotection of the compound of formula (XV) yields the compound of formula (XIII) (RN).

Scheme 8

[0073] The syn theses of compound RI and RO are summarized in Schemes 9 and 10 using a method analogous to that for the preparation of RD. The compound of formula (II) reacts with the compounds of formulae (XVII) and (XX) respectively to give the corresponding compounds of formulae (XVIII) and (XXI). Deproteetion of the compounds of formulae (XVIII) and (XXI) yields desired natural sweeteners RI (X VI) and RO (XIX), respectively.

Scheme 9

Abbreviations

ACN Acetomtrile

EiOAe Ethyl acetate

DMF Dimethyl formamide

PE Peiroieum ether DCM Dichloromethane

THF Tetrahydrofuran

HOAc Acetic acid

Ac 2 0 Acetic anhydride

TEA Triethylamine

DIPEA Diisopfopylethylamine

DM P -Dimethylamin pyridinLe

RD Rebaudioside D

RA Rebaudioside A

ST Stevioside

RB Rebaudioside B

RC Rebaudioside C

RM Rebaudioside M

RN Rebaudioside N

Rl Rebaudioside I

RO Rebaudioside 0

NIS N -iodosuccinimide

DBU 1„8-Diazabicycloundec-7-ene

TsOH p-Toiuenesulfonic acid

TMSOTf Trifluoronietlianesulfoiiic acid trimethyisiiylester

TBSOTf Triiluoromeihanesuifonic acid /-biityldiinethyisilylester

TLC Thin layer chromatography

Aliqua 3 6 Trioctylmethylarnmonium chloride

TBAC tetra-n-butylammonium chloride

TBAB Tetra-« -butylammoni um bromide

TBA1 Tetra-n-butylamraonium iodide

TEBAc Benzyl triethyi ammonium chloride

PTC Phase transferring catalyst

DIC AvV-Diisopropylcarbodiimide

IDCP lodonium dicoUidiiie perchlorate

[0074] Certain specific aspects and embodiments of present invention ;

further detail by the examples below. ' The illustrated examples are not intended to limit the scope of this invention. Examples

Example 1

[0075] Preparation of (2R,3/?,45',5/?,65')-2-(acetoxymethyl)-6- ((2R,3 R,4S, 5R,6R) -4,5

-diacetoxy-6-(acetoxymerthyi)-2-brom

4,5-triyl triacetate (la, a-acetobromosophorose)

[8076] The titled compound is prepared by lit. procedure on J. A. C.S. 78, 4709, 1957.

Example 2

Preparation of RB

[8077] A mixture of RA ( 15 g, 15.5 inmol ) in aqueous ΚΟΗ solution (30 mL, 5%) was stirred at 90 °C for 1 hour. It was cooled to 50 °C, and then neutralized with 6 M aqueous TiCl solution to ρίί 5. The solids were collected by filtration, washed with water and dried to afford Example 5 (RB, 12 g, 98%) as a white solid.

Example 3

[8078] To a suspension of Example 2 (3.48 g, 4.3 mmol) in Ac 2 0 (6 mL, 63.6 mmol), were added DMAP (5 n g, 0.043 mmol) and triethylamine (2 mL, 12.9 mmol) subsequently. The reaction mixture was stirred at 60 °C for 2 hours. After cooled to room temperature, it was partitioned between dichloromethane and water. The organic extracts were concentrated to dryness to afford a residue. To a solution of this residue in MeOH (10 mL), was added 1 % aqueous HCl solution (3 mL) dropwise with stirring. The mixture was stirred for 4 hours. It was neutralized with 2 M KOH to pH 4-5. The methanol was evaporated off in vacuo. The solids were collected by filtration to afford Example 6 (5.0 g, 95 %) 'H-NMR (CDC13): δ 4.7-5.3 ( 10H), 0.9-2.0 (56H).

Example

Preparation of acetylated RD:

General method:

[0079] The mixture of example 3 (1.5 g, 1 eq), appropriate base (CS2CO3, or K2CO3, or K2CO3/KHCO3 buffer, 8 eq), and PTC (TBAB, or TBAL or Aliquat 336, 0.5 eq) in dichloromethane or 1 ,2-diehloroethane (7.5 mL) and water (7.5 mL) was heated at 40-65 °C. To this, was added Example 1 (la', 2.5 eq) over a period of 1.5 hrs. The resulting mixture was stirred at reflux for additional 1.5 hrs. The mixture was allowed to cool to room temperature, and the organic layer was isolated. The aqueous layer was extracted with appropriate solvent. The combined extracts were washed with brine, and dried over anhydrous Na 2 S0 4 . After filtration, the filtrate was concentrated to give the crude acetylated RD (yield: 25-54%). 1 H-NMR (CDClj): δ 5.6 ( d, J= 8.0 Hz, 1H), 3.5-5.4 (m, 36! ! }. 1.9-2.2 (s, 51H, OC(0)CH 3 ), 0.8-1.9 (m, 26! i s.

Example 5

Preparation of RD:

Method A

[8088] To a solution of example 4 (2.0 g, 1.63 mmol) in MeOH (20 mL), was added MeO a/MeOH ( 105 mg, 25%wt, 0,3 eq). The reaction mixture was stirred at room temperature for 2 hrs. It was neutralized with 1 N HCl aqueous solution to pH 6. The solid was collected by filtration and re-crystallized in EtOH/water (2: 1) to afford RD as a white solid (yield: 60-75%). J H-NMR (CD 3 OD): 85.6 C d, J= 8.0 Hz, ! ! ! ;·. 5.3 C s,l H > 4.7-5.0 (m, 5H), 3.0-4.0 (m, 29H), 0.9-2.4 (m, 26H).

[8081] To a solution of example 4 (2.0 g, 1.63 mmol) in MeOH (20 mL), was added K2CO 3 ( 105 mg, 0.3 eq). The reaction mixture was stirred at room temperature for 2 hrs The solid was removed by filtration. The filtrate was neutralized with 1 N HCl aqueous solution to pH 6. The mixture was concentrated collected and re-crystallized in EtOH / water to afford RD as a white solid (yield: 50-70%).

Example 6

Preparation of Xla:

[0082] To a solution of acetylated RB (Example 3, 25. Og, 20 mtnol) in DCM (25 mL) at room temperature was added dropwise of HBr in acetic acid (33%, 12.5 mL) over a period of 30 min. After stirring for 3 hours, the reaction mixture was poured into a mixture of ice-water and DCM (50 mL). The organic layer was separated and washed with water, aqueous aHC(¾ and brine subsequently, dried over anhydrous N¾S0 4 . After filtration, the filtrate was concentrated. The residue was purified by chromatography on silica gel eluting with 10% ethyl acetate in hexane to afford IXa (10.0 g, 50% yield).

Example 7

Preparation of Compound XII (acetylated RM):

[8083] To a solution of acetylated RB (Example 3, 62 g, 50 mmol) in THF (600 mL) and toluene (150 mL), was added water (300 mL) and followed by K2CO 3 (49 g, 354 mmol) and TBAB (8.1 g, 25 mmol). The resulting mixture was heated to 50 ° C . To this, IXa (Example 6, lOOg, lQlmmol) was added poriionwise over 2 hours. After addition, the reaction mixture was stirred for further 2 hours. The mixture was allowed to cool to room temperature, and extracted with ethyl acetate. The combined extracts were washed with brine, dried over anhydrous Na 2 S04. After filtration, the fsitrate was concentrated. ' T ' he residue was purified by chromatography on silica gel eiuting with 10% 50% ethyl acetate in hexane to afford the titled product (57 g, 52% yield).

Example 8

Preparation of Compound X (RM):

[0084] To a solution of aeetykted RM (Example 7, 30 g, 14 mmol) in MeOH (600 mL), was added K 2 COs (960 nig, 6.95 mmol). The reaction mixture was stirred at r.t. overnight. The mixture was neutralized with 1 N HCl aqueous solution to pH 6. The mixture was concentrated collected and re-crystallized in EtOH / water to afford RM as a white solid (10.7g, 58% yield). ¾-NMR (CD 3 OD): δ 5.46 ( d, J= 8.0 Hz, 1H), 5.07 ( s,lH) , 4.78 ( d, J= 7.6 Hz, il-I) , 4.69 (s, lH), 4.64 ( d, 7.6 Hz, 1H) , 4.47-4.52 ( m„ 3H), 2.86 4.0 (m, 36H), 0.78-2.19 (m, 26H).