Stereoselective Synthesis of c/s-4-methylsphingosine and derivatives thereof

Description

The present invention relates to the synthesis of c/s-4-methylsphingosine and derivatives thereof, as well as to ferf-butyl (4S)-4-[(Z, 1 R)-1 -hydroxy-2-methyl-hexadec-2-enyl]-2,2- dimethyl-oxazolidine-3-carboxylate and fert-butyl N-[(Z, 1 S,2R)-2-hydroxy-3-methyl-1 - (tetrahydropyran-2-yloxymethyl)heptadec-3-enyl]carbamate as starting materials or intermediate products. It further relates to (Z, 3S, 4R)-3-amino-5-methyl-nonadec-5-ene-1 ,4- diol and [(Z, 3S, 4R)-3-amino-4-hydroxy-5-methyl-nonadec-5-enyl]phosphonic acid.

Sphingosine-1-phosphate is a lipid messenger molecule and an agonist of specific G-protein coupled receptors S1 P1 to S1 P5. These receptors play an important role in cardiovascular processes, angiogenesis and immune responses.

The compound FTY720 (Fingolimod) is a sphingosine analogue phosphorylated in biological systems to form FTY720-phosphate, which influences S1 P-receptors. The exact mode of action of the compound is currently unknown. The compound is approved for treatment of multiple sclerosis in the European Union, the United States, Switzerland and Russia.

The sphingosine analogue c/s-4-methylsphingosine was synthesised by R. R. Schmidt and co-workers in 1993. Similar to FTY720, this compound is phosphorylated in biological systems and inhibits the activity of different S1 P-receptors. The spectrum of receptors modulated by c/s-4-methylsphingosine is slightly different to that modulated by FTY720. Additionally, c/s-4-methylsphingosine kills neuroblastoma cells.

Following the method of Schmidt, synthesis of c/s-4-methylsphingosine is performed in 9 sequential steps, starting from D-galactose, through a challenging sequence of protection, deprotection and modification steps, at a yield of 0.3%. The time required for a well trained experimenter to perform the synthesis is at least 3 weeks, more likely 3 months.

Because c/s-4-methylsphingosine may support the activity of FTY720, there is interest in and demand for improved methods of its synthesis. Hence, the objective of the present invention is to provide a simple and economical method for preparation of c/s-4-methylsphingosine.

The present invention provides a stereoselective synthesis of c/s-4-methylsphingosine in two steps starting from easily accessible starting material. The overall yield attained is raised to approx. 30 %. This facilitates further characterisation of the substance. The shortened and simplified c/s-4-methylsphingosine synthesis according to the invention will make c/s-4- methylsphingosine more readily available. According to a first aspect of the invention, a method for preparation of a (S-R) dihydroxy- amino-methylalkylene characterized by the general formula la

or its R-S diastereomer is provided, wherein

- R ¹ is CH ₂ OH or CH2-CH2OH, and

R ² is a C ₂ to C2 ₀ alkyl, or an aryl-substituted C ₂ to C ₂₀ alkyl, R ⁸ is methyl and R ⁹ is hydrogen, or

R ² is hydrogen, and R ⁸ and R ⁹ together form an aliphatic carbocycle, optionally substituted by a C ₂ to C ₂₀ alkyl, or a aryl-substituted C ₂ to C ₂₀ alkyl, whereby a compound characterized by the general formula I I or its R-S diastereomer is used as a starting material

wherein R ³ , R ⁴ and R ⁵ have the following meaning:

R ³ is H and R ⁴ is BOC (fert-butoxycarbonyl), or R ³ and R ⁴ are part of a phtalimide group, and R ⁵ is

OPO ₃ ^2" , CH ₂ P0 ₃ ^2" , 0-THP(tetrahydropyranyl ether), O-Bn (benzyl ether), O- TBDMS (ferf-butyldimethylsilyl ether) or O-MOM (methoxymethyl ether ) and n is 1 or 2; or

O-trityl (triphenylmethyl ether) or O-MMT (methoxytriphenylmethyl ether) and n is 2,

or R ⁵ and R ³ together form a propylidene and R ⁴ is H or BOC.

According to one embodiment of the first aspect of the invention, a method for preparation of a (S-R) dihydroxy-amino-methylalkylene characterized by the general formula I is provided

N H ₂ C H ₃ wherein the starting material for the synthesis of I is a compound characterized by the general formula I I

and wherein R ¹ , R ² , R ³ \ R ⁴ and R ⁵ have the meanings indicated above.

While the formulae above show the (2S, 3R) diastereomer (or the (3S, 4R) diastereomer in case of n=2), the (2R, 3S) or (3R, 4S) diastereomer can be obtained similarly by starting with the corresponding chiral educt.

In the context of the instant invention, a propylidene is a moiety described by the formula CH ₃ -C-CH ₃ , wherein the central carbon atom, substituted by two methyl groups, bridges the amino function and the (protected) hydroxyl function of R5 in formula II and formula Ma.

An "alkyl" in the context of the present invention refers to a branched or unbranched hydrocarbon chain. R ² in its broadest sense may be an alkyl of 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms in length, or an aryl-substituted alkyl. An aryl is a cyclic aromatic hydrocarbon.

According to one embodiment, R ² is a saturated or partially unsaturated hydrocarbon chain of 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17 or 18 carbon atoms. According to one embodiment, R ² is a saturated C ₈ -Ci ₅ alkyl. According to one embodiment, R ² is Ci ₃ H ₂₈ . According to one embodiment, R ² is an unsubstituted and saturated alkyl. In one

embodiment, R ² is an unbranched alkyl chain of 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17 or 18 carbon atoms.

According to one embodiment, the alkyl of R ² (as in the definition given in the previous paragraphs) may be substituted by functional groups such as halogen, substituted or unsubstituted amine(s), nitro, cyano, isocyano, thiocyano or isothiocyano groups, alcohol or ether or ester groups or their sulfur analogues. Examples for functional groups are -Br, -CI, - CHO, -COOH, -OH, -HSO3, -NH ₂ , -N0 ₂ , and -S0 ₂ NH ₂ .

An aryl-substituted alkyl in the context of the present invention may be a branched or unbranched hydrocarbon chain of 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms in length which is substituted by aryl groups. The aromatic ring of the aryl may be composed of hetero atoms such as sulfur, oxygen or nitrogen. The aryl may also be substituted by functional groups as described in the preceding paragraph. According to one embodiment, R ² is Ci ₃ H ₂ 8 and the product of synthesis is (2S, 3R, 4Z)- or (2R, 3S, 4Z)-2-amino-4-methyl-octadec-4-ene-1 ,3-diol or (Z ,3S, 4f?)- or (Z, 3R, 4S)-3-amino- 5-methyl-nonadec-5-ene-1 ,4-diol.

According to one embodiment, R ⁸ and R ⁹ together form an cyclohexenyl ring. In one embodiment, R ⁸ and R ⁹ together form cyclohexenyl ring substituted in position 2 by a saturated or partially unsaturated hydrocarbon chain of 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17 or 18 carbon atoms.

According to one embodiment, a method for preparation of an S-R-dihydroxy-amino- methylalkylen I or la or its R-S diastereomer is provided, wherein the compound

characterized by the general formula II or Ma is converted in the presence of a strong organic acid. Trifluoroacetic acid or a similar protic acid is preferred.

According to one embodiment, the reaction is performed in an aprotic, polar solvent, for example dichloroethane. According to one embodiment, the conversion reaction is performed at low temperatures, preferably at 0 °C.

According to one embodiment of the first aspect of the invention, a method for preparation of of a (S-R) dihydroxy-amino-methylalkylene characterized by the general formula lb

or its R-S diastereomer is provided, whereby a compound characterized by the general formula I I

or its R-S diastereomer is used as a starting material, wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ have the meanings indicated above.

According to another embodiment, the method of the invention provides for preparation of a (S-R) dihydroxy-amino-methylalkylene characterized by formula lc or its R-S diastereomer

whereby a compound characterized by the formula II or its R-S diastereomer

or its R-S diastereomer is used as a starting material, wherein R ¹ , R ³ , R ⁴ and R ⁵ have the meanings indicated above.

According to one embodiment of the first aspect of the invention, a method for preparation of a S-R-dihydroxy-amino-methylalkylen I, la, lb, Ic or its R-S diastereomers is provided, wherein the compound characterized by the general formula II, Ma, lib or lie is

a) fert-butyl (4S)-4-[(Z, 1 R)-1 -hydroxy-2-methyl-hexadec-2-enyl]-2,2-dimethyl- oxazolidine-3-carboxylate III

or its diastereomer fert-butyl (4R)-4-[(Z, 1 S)-1-hydroxy-2-methyl-hexadec-2

dimethyl-oxazolidine-3-carboxylate,

b) fert-butyl N-[(Z, "I S, 2R)-2-hydroxy-3-methyl-1 -(tetrahydropyran-2- yloxymethyl)heptadec-3-enyl]carbamate IV

(IV) or its diastereomer fert-butyl N-[(Z, ^* \ R, 2S)-2-hydroxy-3-methyl-1 -(tetrahydropyran-2- yloxymethyl)heptadec-3-enyl]carbamate,

c) fert-butyl (4S)-4-[(R)-hydroxy-(2-tetradecylcyclohexen-1 -yl)methyl]-2,2-dimethyl- oxazolidine-3-carboxylate

or its diastereomer fert-butyl (4R)-4-[(S)-hydroxy-(2-tetradecylcyclohexen-1-yl)methyl]-2,2 - dimethyl-oxazolidine-3-carboxylate, or

d) fert-butyl (4S)-4-[(R)-(4-fert-butylcyclohexen-1 -yl)-hydroxy-methyl]-2,2-dimethyl- oxazolidine-3-carboxylate

or its diastereomer fert-butyl (4R)-4-[(S)-(4-ferf-butylcyclohexen-1-yl)-hydroxy-methyl]-2, 2- dimethyl-oxazolidine-3-carboxylate.

According to one embodiment of the first aspect of the invention, a method for preparation of an S-R-dihydroxy-amino-methylalkylen I, la or its R-S diastereomer is provided. Therein a vinyl halide characterized by the general formula

(V) , wherein R ² , R ⁸ and R ⁹ have the meanings given above and X can be CI, Br or I, is used as an intermediate to generate the starting material for the synthesis of the present invention. In one embodiment, the intermediate is any of

(Vc). According to one embodiment, the bromides of Va, Vb or Vc are employed.

Preferred exemplary intermediates are vinyl bromide (Z)-2-bromohexadec-2-ene VI,

1-bromo-2-tetradecyl-cyclohexene VI b.

According to one embodiment, a method for preparation of an S-R-dihydroxy-amino- methylalkylen I, la or its R-S diastereomer is provided, wherein the vinyl bromide is prepared from a ketoalkyl compound characterized by the general formula VII

(VII), wherein R ² , R ⁸ and R ⁹ have the meanings given above.

In one embodiment, the ketoalkyl compound is described by

In one embodiment, hexadecan-2-one is converted to (Z)-2-bromohexadec-2-ene.

According to one embodiment, the cyclohexenyl bromide is prepared from a cycloh alkyl compound characterized by the general formula VI lb.

(VI lb)

In one embodiment, 2-tetradecylcyclohexanone is converted to 1-bromo-2-tetradecyl- cyclohexene.

In one embodiment, the alkyl compound is a cyclohexanone Vile.

(Vile)

In one embodiment, 4-ferf-butylcyclohexanone is converted to 1 -bromo-4-fert-butyl- cyclohexene.

According to one embodiment, a method for preparation of a S-R-dihydroxy-amino- methylalkylen I, la or its R-S diastereomer is provided, wherein a protected homoserine derivative of the general formula VIII

(VIII)

wherein

R ⁶ is H or a amino protecting group, and

R ⁷ is H, P0 ₃ ^2" , THP, Bn (benzyl), TBDMS, MOM, trityl or MMT,

is reacted with the alkenyl bromide.

The term amino protecting group in the sense of the present invention refers to a functional group that can be easily attached to and removed from amino groups under mild chemical conditions. Such amino protecting groups are, without being restricted to, BOC, Fmoc (fluorenylmethyloxicarbonyl), benzyloxycarbonyl or allyloxycarbonyl.

According to one embodiment, a method for preparation of a S-R-dihydroxy-amino- methylalkylen I, la or its R-S diastereomer is provided, wherein the protected homoserine derivative is fert-butyl N-[(1 S)-1-formyl-3-tetrahydropyran-2-yloxy-propyl]carbamate IX

and IX is obtained by reduction of benzyl (2S)-2-(fert-butoxycarbonylamino)-4- tetrahydropyran-2-yloxy-butanoate X

According to one preferred embodiment, the method for preparation of a S-R-dihydroxy- amino-methylalkylen I, la or its R-S diastereomer is preceded by a step in which benzyl (2S)- 2-(fert-butoxycarbonylamino)-4-hydroxy-butanoate or its diastereomer

is used as starting material in a reaction to obtain benzyl (2S)-2-(ferf-butoxycarbonylamino)- 4-tetrahydropyran-2-yloxy-butanoate X.

According to one embodiment, the method of the previous paragraph may be preceded by a step, wherein (2S)-2-(fert-butoxycarbonylamino)-4-hydroxy-butanoic acid

is converted to benzyl (2S)-2-(fert-butoxycarbonylamino)-4-hydroxy-butanoate XIV.

XV may be obtained by protecting the amino function of homoserine with the BOC group.

According to one embodiment, a method for preparation of a S-R-dihydroxy-amino- methylalkylen I, la or its R-S diastereomer is provided, wherein fert-butyl (4S)-4- [methoxy(methyl)carbamoyl]-2,2-dimethyl-oxazolidine-3-carbox ylate IXb

is used as a starting in a reaction to obtain fert-butyl (4S)-4-[(Z, 1 R)-1-hydroxy-2-methyl- hexadec-2-enyl]-2,2-dimethyl-oxazolidine-3-carboxylate III, fert-butyl (4S)-4-[(R)-hydroxy-(2- tetradecylcyclohexen-1 -yl)methyl]-2,2-dimethyl-oxazolidine-3-carboxylate 1Mb, or fert-butyl (4S)-4-[(R)-(4-tert-butylcyclohexen-1 -yl)-hydroxy-methyl]-2,2-dimethyl-oxazolidine-3- carboxylate I lie.

According to one aspect of the invention, products of a method of synthesis according to the first aspect of the invention, or derivatives thereof, are provided. These products can be used in assays or as candidate compounds for pharmaceutical development, for example as substitutes for sphingosine or as agonists or antagonists for sphingosine receptors. The compounds thus provided are

(Z, 3S ,4R)-3-amino-5-methyl-nonadec-5-ene-1 ,4-diol XI

[(Z, 3S, 4R)-3-amino-4-hydroxy-5-methyl-nonadec-5-enyl] dihydrogen phosphate XVI

and

[(Z, 3S, 4R)-3-amino-4-hydroxy-5-methyl-nonadec-5-enyl]phosphonic acid XII

(1 R, 2S)-2-amino-1-(2-tetradecylcyclohexen-1-yl)propane-1 ,3-diol

(1 R, 2S)-2-amino-1-(4-tert-butylcyclohexen-1 -yl)propa

O H

(XVIII)

According to one aspect of the invention, the following intermediates of a method of synthesis according to first aspect of the invention are provided:

-fert-butyl (4S)-4-[(Z, 1 R)-1 -hydroxy-2-methyl-hexadec-2-enyl]-2,2-dimethyl-oxazolidine-3 - carboxylate III

fert-butyl N-[(Z, 1 S, 2R)-2-hydroxy-3-methyl-1 -(tetrahydropyran-2-yloxymethyl)heptadec-3- enyl]carbamate XIV

(Z)-2-bromohexadec-2-ene VI

fert-butyl N-[(1 S)-1-formyl-3-tetrahydropyran-2-yloxy-propyl]carbamate IX

benzyl (2S)-2-(fert-butoxycarbonylamino)-4-tetrahydropyran-2-yloxy- butanoate X

1-bromo-2-tetradecyl-cyclohexene VI b

fert-butyl (4S)-4-[(R)-hydroxy-(2-tetradecylcyclohexen-1 -yl)methyl]-2,2-dimethyl-oxazolidine- 3-carboxylate 1Mb

fert-butyl (4S)-4-[(R)-(4-tert-butylcyclohexen-1 -yl)-hydroxy-methyl]-2,2-dimethyl-oxazolidine- 3-carboxylate 111 c

According to one aspect of the invention, a method for the synthesis of an intermediate or starting material for a method of synthesis according to the first aspect of the invention is provided, wherein the compound characterized by the general formula II, wherein R ² , R ³ , R ⁴ and R ⁵ have the meaning specified above, is obtained by reacting an vinyl bromide of general formula V with an aldehyde compound characterized by the general formula XIII, wherein n, R ³ , R ⁴ and R ⁵ have the meaning specified above.

According to one aspect of the invention, a method for the synthesis of an intermediate or starting material for a method of synthesis according to the first aspect of the invention is provided, wherein fert-butyl N-[(1 S)-1-formyl-3-tetrahydropyran-2-yloxy-propyl]carbamate IX is obtained by reduction of benzyl (2S)-2-(fert-butoxycarbonylamino)-4-tetrahydropyran-2- yloxy-butanoate X.

The synthesis described in the present invention enables production of c/s-4- methylsphingosine in 3 to 5 days starting from commercially available compounds such as Garner aldehyde and hexadecanone. Synthesis yield is 27.6 %, a 100-fold increase compared to the synthesis described by Schmidt. Significant time and cost savings are the result. Intermediates (Z)-2-bromohexadecanone and (S)-tert-butyl-4-((R, Z)-1 -hydroxy-2- methylhexadec-2-enyl)-2,2-dimethyloxazolidin-3-carboxylate are novel compounds not yet described in the literature. The formation of Z-alkenes from 2-ketones and the use of lithium- vinyl compounds and vinyl-Grignard-compounds are known and described in detail.

Intermediates are characterised by ¹ H-NMR, ¹³ C-NMR, IR, optical rotation value and high- resolution-MS herein. The method of the invention is simple, fast and cost-effective. Addition derivates of c/s-4-methylsphingosine like compound 5 ((Z, 3S, 4R)-3-amino-5-methyl- nonadec-5-ene-1 ,4-diol) or metabolically stable phosphate-analogues like [(Z, 3S, 4R)-3- amino-4-hydroxy-5-methyl-nonadec-5-enyl]phosphonic acid are thus provided.

Wherever reference is made herein to an embodiment of the invention, and such

embodiment only refers to one feature of the invention, it is intended that such embodiment may be combined with any other embodiment referring to a different feature.

The invention is further characterized, without limitations, by the following examples, from with further features, advantages or embodiments can be derived. The examples do not limit but illustrate the invention.

Description of the figures

Figure 1 shows the reaction scheme of (2S, 3R, 4Z)-2-amino-4-methyl-4-octadecene-1 ,3-diol synthesis.

Figure 2 shows the reaction scheme of (Z, 3S, 4R, 5Z)-3-amino-5-methyl-nonadec-5-ene- 1 ,4-diol synthesis.

Figure 3 shows yields of the reaction of (2S, 3R, 4Z)-2-amino-4-methyl-4-octadecene-1 ,3-diol synthesis, with the reagents: i) acetyl bromide; ii) butyllithium; iii) trifluoroacetic acid in dichloromethane.

Figure 4 shows the reaction scheme of tert-butyl (4S)-2,2-dimethyl-4-(2-methylprop-2- enoyl)oxazolidine-3-carboxylate synthesis, with the reagents: i) butyllithium; ii) diisobutylaluminium hydride.

Figure 5 shows the reaction schemes of (1 R, 2S)-2-amino-1-(4-tert-butylcyclohexen-1 - yl)propane-1 ,3-diol synthesis and (1 R, 2S)-2-amino-1-(2-tetradecylcyclohexen-1 - yl)propane-1 ,3-diol synthesis, with the reagents: i) acetyl bromide; ii) butyllithium; iii) trifluoroacetic acid in dichloromethane.

Examples

Synthesis of (Z)-2-bromohexadec-2-ene

To an ice cooled solution of 200 mg (0.834 mmol) hexadecan-2-one in 3 ml methanesulfonic acid 248 μΙ acetylbromide (3.336 mmol, 4 eq.) was added drop wise. Stirring was continued for 5 h in an ice bath and then 10 h at RT. The mixture was poured into 50 ml ice cooled aqueous 10 % NaOH solution and extracted with 30 ml ethyl acetate. The organic layer was washed with 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . The solvent was removed to give 260 mg slightly yellow oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane. Yield: 228 mg (0.755 mmol, 90.5 % d. Th.) colorless liguid, Ci ₆ H ₃ iBr (302.5 g/mol).

R _f (cyclohexane/ethyl acetate 4: 1 ) = 0.75

1 H-NMR (CDCI ₃ ; 500.1 M Hz): δ = 0.88 (t, J _f =6.9 Hz, J ₂ =6.9 Hz, 3H, CH ₃ ) 1 .25-1 .28 (m, 20H), 1 .37 (m, 2H, CH ₂ -5), 2.12 (dd, 2H, J _f =6.9 Hz, J ₂ =14.6 Hz, CH ₂ -4), 2.27 (d, J=1 .3 Hz, 3H, CH ₃ -1 ), 5.60 (td, .3 Hz, J ₂ =6.9 Hz, 1 H, CH) ppm.

¹³ C-NMR (CDCI ₃ ; 125.8 MHz): δ = 14.1 , 22.7, 28.5, 28.8, 29.2, 29.4, 29.5, 29.6, 29.7, 31 .5, 32.0, 41 .2, 53.0, 122.1 , 129.2 ppm.

I R (neat) u (cm ^"1 ) = 2955, 2922, 2852, 1549, 564, 549, 541 , 527.

HRMS EI+ calculated for Ci ₆ H ₃ i ⁷⁹ Br m/z = 302.1609, found 302.1609.

HRMS EI+ calculated for d ₆ H ₃ i ⁸¹ Br m/z = 304.1589, found 304.1591 .

Synthesis of (S)-terf-butyl 4-((R, Z)-1 -hydroxy-2-methylhexadec-2-enyl)-2,2- dimethyloxazolidine-3-carboxylate

(I II)

To a stirred solution of 50 mg (0.16 mmol) (Z)-2-bromohexadec-2-ene in 5 ml THF at -78 °C 0.1 ml t-BuLi-Solution (1 .7 M in pentane) was added dropwise After 3 min 100 μΙ TMEDA were added. Stirring was continued for 3 min at -78 °C. A solution of 38 mg (0.16 mmol) Garner aldehyde in 5 ml THF was added drop wise and stirring continued for 8 min. The mixture was poured into 10 ml ice cooled water and extracted three times with 10 ml Ethyl acetate. The combined organic layer was washed with 20 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 60 mg slightly yellow oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 9: 1 -3: 1 . Yield: 228 mg (0.755 mmol, 31 .7 % d. Th.) colorless liquid, Ci ₆ H ₃ iBr (302.5 g/mol). R _f (cyclohexane/ethyl acetate 5.5: 1 .5) = 0.27

[a] _D ²⁰ = - 43.8° (c = 1 .00; CHCI ₃ ) ¹ H-NMR (CDCI ₃ ; 500.1 MHz): δ = 0.83 (t, J _f =6.9 Hz, J ₂ =6.9 Hz, 3H, CH ₃ ) 1 .20 (s, 22H), 1.37- 1.47 (m, 15H, BOC, 2 CH ₃ ), 1 .73 (s, 3H, CH ₃ -4), 1 .95-2.00 (m, 1 H, CH ₂ -6), 2.04-2.08 (m, 1 H, CH2-6), 3.89 (bs, 1 H, OH), 4.01-4.07 (m, 2H, CH ₂ -1 ), 4.22 (bd, 1 H, CH-2), 4.62 (d, 1 H, J=5.0 Hz, CH ₂ -3), 5.24 (t, Ji=7.1 Hz, J ₂ =7.1 Hz, 1 H, CH-5) ppm.

1 ³ C-NMR (CDCI ₃ ; 125.8 MHz): δ = 14.1 , 22.7, 26.9, 28.0, 28.4, 29.4, 29.6, 29.6, 29.7, 31 .9, 64.5, 70.2, 80.4, 129.9 ppm.

IR (neat) u (cm ^"1 ) = 3006, 2980, 2940, 2883, 1694, 1392, 1383, 1366, 1253, 1 173, 1097. HRMS EI+ calculated for C ₂ 7H ₅ iN ₁ 04 m/z = 453.3818, found 453.3818.

Synthesis of (2S, 3ft, 4Z)-2-amino-4-methyl-4-octadecene-1 ,3-diol.

To an ice cooled solution of 125 mg (0.276 mmol) (S)-fert-Butyl-4-((R, Z)-1 -hydroxy-2- methylhexadec-2-enyl)-2,2-dimethyloxazolidine-3-carboxylate in 10 ml CH ₂ CI ₂ was added 1 ml trifluoroacetic acid drop wise. Stirring was continued for 5 min in an ice bath. The mixture was poured into 50 ml ice cooled 10 % NaOH solution and extracted with 30 ml CH ₂ CI ₂ . The organic layer was washed with 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 93 mg colorless oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 4:1-1 :1. Yield: 75 mg (0.755 mmol, 87.2 % d. Th.) colorless solid, Οι ₉ Η ₃₉ Ν0 ₂ (313.8 g/mol).

R _f (cyclohexane/ethyl acetate 1 :1 ) = 0.27 [a] _D ²⁰ = - 18.8° (c = 1.00; CHCI ₃ )

1H-NMR (CDCI ₃ ; 500.1 MHz): δ = 0.88 (t, J _f =6.9 Hz, J ₂ =6.9 Hz, 3H, CH ₃ ) 1 .25 (s, 22H), 1 .76 (s, 3H, CH ₃ -4), 1.94-2.01 (m, 1 H, CH ₂ -6), 2.02-2.12 (m, 1 H, CH ₂ -6), 2.27 (bs, 4H, 2 OH, NH ₂ ,), 3.60 (br, 1 H, CH-2), 3.80 (dd, 1 H, J _f =2.8 Hz, J ₂ =1 1 .3 Hz, CH ₂ -1 a), 3.96 (dd, 1 H, Ji=3.6 Hz, J ₂ =1 1.3 Hz, CH ₂ -1 b) 4.68 (d, 1 H, J=7.4 Hz, CH ₂ -3), 5.36 (t, J _f =7.3 Hz, J ₂ =7.3 Hz, 1 H, CH-5) ppm.

1 ³ C-NMR (CDCI ₃ ; 125.8 MHz): δ = 14.1 , 18.3, 22.7, 27.6, 28.3, 28.4, 29.4, 29.6, 29.6, 29.7, 29.7, 30.0, 31.9, 54.2, 63.5, 70.7, 130.5, 133.6 ppm.

IR (neat) u (cm ^"1 ) = 3386, 2955, 2917, 2849, 1691 , 1663, 1527, 1469, 1294, 1249, 1 165, 1055, 1027, 997.

MS ESI+ calculated forCi ₉ H ₃₉ N0 ₂ +H ⁺ m/z = 314.306, found 314.31 1.

MS ESI+ calculated for Ci ₉ H ₃₉ N0 ₂ +Na ⁺ m/z = 336.288, found 336.296. HRMS EI+ calculated for C1 ₉ H ₃₉ NO2 m/z = 313.2981 , found 313.2981 .

Synthesis of (S)-2 (te/t-butyloxycarbonylamino)-4-hydroxybutyric acid sodium salt

1 .0 g (8.4 mmol) homoserine was suspended in 10 ml dioxane and 15 ml water. 1 .77 g (21 mmol) NaHC0 ₃ was added. The solution was cooled to -15 °C and a solution of 2 g (9.2 mmol) di-fert-butyl dicarbonate in 5 ml dioxane added drop wise stirring was continued for 12 h at RT. 1 M HCI solution was added until the pH-value became acidic. It was extracted 3 times with 50 ml ethyl acetate. Combined organic layers were washed with 50 ml saturated NaHC0 ₃ solution and dried over Na ₂ S0 ₄ . The solvent was removed to give 1 .8 g (8.2 mmol, 97.6 % d. Th.) colorless solid (C ₉ H ₁₇ N0 ₅ (219.2 g/mol)) as crude product, which was used without further purification.

R _f (ethyl acetate/methanol 98:2) = 0.24 [a] _D ²⁰ = - 24.9° (c = 1 .00; Methanol)

¹ H-NMR (CDCI ₃ ; 500, 1 MHz): δ = 1 .45 (s, 10H, BOC, OH), 2.19 (m, 1 H, CH ₂ -3), 2.75 (br m, 1 H, CH ₂ -3), 4.24 (ddd, Ji=5.9 Hz, J ₂ =9.3 Hz, J ₃ =1 1 .4 Hz, 1 H, CH ₂ -4), 4.24 (br s, 1 H, CH ₂ -4), 4.43 (t, Ji=9.0 Hz, J ₂ =9.0 Hz, 1 H, CH-2), 5.10 (bs, 1 H, NH) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 28.2, 30.6, 50.2, 65.7, 80.6, 155.4, 175.3 ppm.

MS ESI+ calculated for C ₉ H ₁₆ N0 ₅ m/z = 218.1 , found 218.1 .

Synthesis of (S) - 2 (fe/t-butyloxycarbonylamino)-4-hydroxybutyric acid benzylester

The crude product (8.4 mmol) of the BOC-homoserine protection was converted to the Sodium salt with NaOH (8.5 mmol) in 10 ml H ₂ 0 and 15 ml ethanol. The salt was suspended in 10 ml dimethylformamide and 1 .00 ml (1 .44 g, 8.5 mmol) benzylbromide added. The solution was stirred for 12 h at RT. 1 M HCI solution was added until the pH-value became acidic. This was extracted 3 times with 20 ml ethyl acetate. Combined organic layers were washed with 30 ml saturated NaHC0 ₃ solution and dried over Na ₂ S0 ₄ . The solvent was removed under vacuum. The crude product was purified by chromatography on silica gel eluted with cyclohexane/ ethyl acetate 3:1 -1 :1 . Yield: 2.04 g (6.6 mmol, 80.6 %) colorless solid, C1 ₆ H2 ₃ NO ₅ (309.1 g/mol). Crude product was used without further purification.

R _f (cycolhexane/ethyl acetate 3:1 ) = 0.15 [a] _D ²⁰ = + 5.9° (c = 1 .00; Chloroform)

¹ H-NMR (CDCI ₃ ; 500,1 MHz): δ = 1.43-1 .45 (s, 9H), 2.16 (m, 1 H, CH ₂ -3), 2.30 (br m, 1 H, CH ₂ -3), 4.24 (ddd, Ji=5.9 Hz, J ₂ =9.3 Hz, J ₃ =1 1 .4 Hz, 1 H, CH ₂ -4), 4.34 (br s, 1 H, CH ₂ -4), 4.43 (t, Ji=8.8 Hz, J ₂ =8.8 Hz, 1 H, CH-2), 4.69 (s, 2H, CH ₂ -phenyl), 5.18 (d, Ji=3.7 Hz, 1 H), 7.33 (m, 5H, phenyl) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 28.3, 30.7, 36.2, 50.7, 58.3, 65.4, 65.8, 67.3, 80.5, 127.0, 127.6, 128.3, 128.6, 128.6, 140.9, 172.7 ppm.

HRMS ESI+ calculated for Ci ₆ H ₂₃ N ₁ 0 ₅ +H ⁺ m/z = 310.1649, found 310.1650.

Synthesis of terf-butyl (S)-1-((benzyloxy)carbonyl)-3-(tetrahydro-2H-pyran-2- yloxy)propylcarbamate

(X)

2.04 mg (6.6 mmol) of BOC-homoserinebenzylester was dissolved in 10 ml toluene. 800 μΙ dihydropyran and a catalytic amount of p-TosOH were subsequently added. The reaction mixture was stirred for 45 min at RT. Saturated NaHC0 ₃ solution was added and the solution extracted twice with 50 ml ethyl acetate. Combined organic layers were washed with 30 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . After the solvent was removed under reduced pressure, the crude product was purified by chromatography on silica gel eluted with cyclohexane/ ethyl acetate 9:1-4:1. Yield: 2.04 g (5.09 mmol, 76 %) colorless oil, C ₂ iH ₃ iN0 ₆ (393.2 g/mol).

R _f (cycolhexane/ethyl acetate 3:1 ) = 0.36

[a] _D ²⁰ = - 10.2° (c = 1 .00; chloroform)

¹ H-NMR (CDCI ₃ ; 500.1 MHz): δ = 1 .43-1.45 (s, 9H, BOC), 1.52-1 .60 (m, 4H), 1 .67-1.72 (m, 1 H), 1.78-1 .84 (m, 1 H), 2.03-2.1 1 (m, 1 H), 2.12-2.19 (m, 1 H), 3.40-3.52 (m, 2H), 3.79-3.88 (m, 2H), 4.48 (dd, J _f =6.4, J ₂ =1 1.8 Hz, 1 H), 4.55 (td, Ji=3.4, J ₂ =3.4, J ₃ =19.4 Hz, 1 H), 5.16 (dd, Ji=1.9, J ₂ =12.2 Hz, 1 H), 5.21 (dd, J _f =5.2, J ₂ =12.3 Hz, 1 H), 5.57 (dd, J _f =7.7, J ₂ =21.7 Hz, 1 H), 7.33-38 (m, 5H, phenyl) ppm. ¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 19.2, 25.4, 26.3, 28.3, 30.4, 31 .5, 31 .8, 52.0, 61 .7, 62.1 , 63.6, 63.9, 66.9, 79.6, 99.0, 128.2, 128.3, 128.6, 135.5, 155.4, 172.4 ppm.

HRMS ESI+ calculated for C ₂ iH ₃ iN0 ₆ +H ⁺ m/z = 394.2224, found 394.2226.

Synthesis of terf-butyl (S)-1-formyl-3-(tetrahvdro-2H-pyran-2-yloxy)propylcarbamate

(IX)

A solution of 2.04 g (5.09 mmol) tert-butyl (S)-1-((benzyloxy)carbonyl)-3-(tetrahydro-2H- pyran-2-yloxy)propylcarbamate in 30 ml toluene was cooled to -78 °C. 8.5 ml DIBALH solution 1.2 M in toluene was added drop wise The reaction mixture was stirred for 2 h at - 78 °C. 5 ml methanol was added at -78 °C. The reaction mixture was allowed to warm to RT. Water was added and the reaction mixture was extracted twice with 30 ml ethylacetate.

Combined organic layers were washed with 30 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Subsequently the solvent was removed under reduced pressure, the crude product was purified by chromatography on silica gel eluted with cyclohexane/ ethyl acetate 9:1-4:1. Yield: 1 .25 g (4.34 mmol, 85.6 %) colorless oil, Ci ₄ H ₂₅ N0 ₅ (287.3 g/mol).

R _f (cycolhexane/ethyl acetate 3:1 ) = 0.20

[a] _D ²⁰ = + 25.8° (c = 1.00; chloroform)

¹ H-NMR (CDCI ₃ ; 500.1 MHz): δ = 1.44 (s, 9H, BOC), 1 .48-1.57 (m, 4H), 1.62-1 .68 (m, 1 H), 1.72-1 .78 (m, 1 H), 2.07-2.23 (m, 2H), 3.41-3.51 (m, 2H), 3.72-3.86 (m, 2H), 4.28 (m, 1 H), 4.52 (td, Ji=3.0, J ₂ =3.0, J ₃ =7.0 Hz, 1 H), 5.56 (dd, Ji=4.4, J ₂ =39.7 Hz, 1 H), 9.59 (s, 1 H, aldehyde) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 19.2, 19.3, 25.3, 28.3, 29.3, 29.5, 30.5, 62.3, 63.0, 98.9, 155.7, 199.3 ppm.

HRMS ESI+ calculated for Ci ₄ H ₂₅ N0 ₅ +H ⁺ m/z = 288.1805, found 288.1806.

Synthesis of 1 -bromo-4-terf-butylcyclohex-1 -ene

To an ice cooled solution of 1.0 g (6.5 mmol) 4-ferf-butylcyclohexanone in 10 ml methanesulfonic acid 1 .92 ml acetyl bromide (1 .15 g, 9.4 mmol) were added drop wise. Stirring was continued for 2 h in an ice bath. The mixture was poured in 100 ml ice cooled 10 % NaOH solution and extracted with 100 ml ethyl acetate. Organic layer was washed with 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give slightly yellow oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane. Yield: 1.3 g (5.99 mmol, 92.2 % d. Th.) colorless liquid, Ci ₀ H ₁₇ Br (217.0 g/mol).

R _f (cycolhexane/ethyl acetate 9:1 ) = 0.75

¹ H-NMR (CDCI ₃ ; 500 MHz): δ = 0.86 (s, 9H, 3 * CH ₃ ), 1.28-1 .40 (m, 2H), 1 .81 -1.89 (m, 2H), 2.05-2.12 (m, 1 H), 2.44-2.48 (m, 2H), 6.03 (ddd, 1 H, J _f =2.1 Hz, J ₂ =3.5 Hz, J ₃ =5.7 Hz), ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 25.9, 27.1 , 29.0, 32.1 , 36.4, 42.8, 121 .9, 128.9 ppm.

Synthesis of 1 -chloro-4-terf-butylcyclohex-1-ene

To an ice cooled solution of 1.5 g (9.7 mmol) 4-fert-butylcyclohexanone in 8 ml

methanesulfonic acid 1 .92 ml pivaloyl chloride (1 .96 g, 16.3 mmol) were added drop wise. Stirring was continued for 3 h in an ice bath. The mixture was poured in 100 ml ice cooled 10 % NaOH solution and extracted with 100 ml ethyl acetate. Organic layer was washed with 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane. Yield: 0.9 g (5.2 mmol, 53.9 % d. Th.) colorless liquid, Ci ₀ H ₁₇ CI (172.7 g/mol).

R _f (cyclohexane/ethyl acetate 9:1 ) = 0.75

EA calculated for CioH ₁₇ CI: C 69.55; H 9.92; CI 20.5; found: C 80.20; H 1 1.19; CI 5.61.

Synthesis of (S)-terf-butyl 4-((R)-(4-tert-butylcyclohex-1-enyl)(hydroxy)methyl)-2,2- dimethyloxazolidine-3-carboxylate

To a stirred solution of 300 mg (1 .39 mmol) 1 -bromo-4-ferf-butylcyclohex-1-ene in 5 ml THF at -78 °C 0.80 ml (1.39 mmol) t-BuLi-Solution (1 .7 M in pentane) were added drop wise. After 3 min 100 μΙ TMEDA were added. Stirring was continued for 3 min at -78 °C. A solution of 318 mg (1.39 mmol) Garneraldehyde in 5 ml THF was added drop wise and stirring was continued for 1 h. The mixture was poured in 10 ml ice cooled water and extracted with three times with 10 ml Ethyl acetate. Combined organic layer was washed with 20 ml saturated NaCI-Solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 400 mg slightly yellow oil as crude product, which was purified by chromatography on silica gel eluted with

cyclohexane/ethyl acetate 9:1 -4:1 . Yield: 196 mg (0.534 mmol, 38.5 % d. Th.) colorless liquid, C ₂ iH ₃₇ N0 ₄ (367.5 g/mol).

R _f (cyclohexane /ethyl acetate 7:3) = 0.50

¹ H-NMR (CDCI ₃ ; 500 MHz): δ = 0.85 (d, J =1 .6 Hz, 9H), 1 .42-1.43 (m, 2H), 1.48 (s, 6H), 1.50 (s, 9H), 1.71 -1 .97 (m, 3H), 1 .96-2.10 (m, 2H), 3.76 (dd, J =9.1 Hz, J ₂ =9.1 Hz, 1 H), 3.84 (dd, Ji=5.8 Hz, J ₂ =8.0 Hz, 1 H), 4.02 (dd, Ji=9.9 Hz, J ₂ =9.9 Hz, 1 H), 4.09 (br, 1 H), 5.70 (m, 1 H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 14.2, 21 .1 , 23.9, 24.8, 26.7, 26.8, 27.2, 28.3, 28.4, 32.1 , 32.3, 44.5, 60.4, 66.5, 80.2, 95.0, 1 19.0, 126.6, 171.6 ppm.

HR-MS p ESI calculated for C ₂ iH ₃₇ N0 ₄ +H ⁺ m/z = 368.2796, found: 368.2795.

HR-MS p ESI calculated for C ₂ iH ₃₇ N0 ₄ +Na ⁺ m/z = 390.2616, found: 390.2615.

Synthesis of (1 ft,2S)-2-amino-1 -(4-terf-butylcyclohex-1 -enyl)propane-1 ,3-diol

(XVIII)

To an ice cooled solution of 60 mg (0.163 mmol) (S)-fert-butyl 4-((R)-(4-fert-butylcyclohex-1- enyl)(hydroxy)methyl)-2,2-dimethyloxazolidine-3-carboxylate in 6 ml CH ₂ CI ₂ was added 0.3 ml trifluoroacetic acid drop wise. Stirring was continued for 20 min in an ice bath. The mixture was poured in 10 ml ice cooled 10 % NaOH solution and extracted with 20 ml CH ₂ CI ₂ . Organic layer was washed with 20 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 43 mg colorless oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 4:1 -1 :1 to yield: 23 mg (0.101 mmol, 62.0 % d. Th.) colorless solid, d ₃ H ₂₅ N0 ₂ (227.3 g/mol). R _f (cyclohexane /ethyl acetate 1 :1 ) = 0.15

¹ H-NMR (CDCI ₃ ; 500 MHz): δ = 0.78 (d, J _f =1 .9 Hz, 9H), 1 .02-1.10 (m, 1 H), 1 .12-1.20 (m, 1 H), 1 .68-1.76 (m, 1 H), 1.76-1 .87 (m, 2H), 1 .98-2.14 (m, 2H), 2.50 (br, 2H), 3.66-3.74 (m, 3H), 4.14 (dd, Ji=3.4 Hz, J ₂ =26.2 Hz, 1 H), 5.05 (dd, J =6.4 Hz, J ₂ =30.7 Hz, 1 H), 5.66 (br, 1 H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 23.9, 26.2, 26.6, 27.1 , 28.3, 32.2, 44.1 , 53.3, 64.9, 123.3, 137.0 ppm. Mixture of epimeres, all as duplet.

HR-MS p ESI calculated for Ci ₃ H ₂₅ N02+H ⁺ m/z = 228.1958, found: 228.1958.

Synthesis of 2-tetradecylcyclohexanone

To a refluxing solution of 5.37 g (48.0 mmol) potassium-ferf-butanolate in 50 ml t-butanol 5.0 ml (48.0 mmol) cyclohexanone and 14.3 ml (48.0 mmol) 1-bromotetradecan were added similar. The reaction mixture was stirred for 2 h at reflux. The reaction mixture was diluted with 100 ml ethyl acetate. Organic layer was washed with 50 ml water, 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 43 mg colorless oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 1 :0-9:1 to yield: 5.86 g (19.9 mmol, 41.5 % d. Th.) colorless liquid, C ₂₀ H ₃₈ O

(294,5 g/mol).

R _f (cyclohexane /ethyl acetate 9:1 ) = 0.58

1H-NMR (CDCI ₃ ; 500 MHz): δ = 0.87 (t, J _f =6.9 Hz, J ₂ =6.9 Hz, 3H, CH ₃ ), 1 .24 (s, 25H), 1.34- 1.42 (m, 1 H), 1.51-1.70 (m, 3H), 1.75-1 .85 (m, 2H), 1 .99-2.1 1 (m, 2H), 2.22-2.39 (m, 2H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 14.1 , 22.7, 24.8, 27.2, 28.0, 29.3, 29.4, 29.5, 29.6, 29.7, 29.7, 29.8, 31.9, 33.8, 41 .9, 50.7, 213.5 ppm.

HR-MS p ESI calculated for C ₂₀ H ₃₈ O +H ⁺ m/z = 295.2995, found: 295.2994.

HR-MS p ESI calculated for C ₂₀ H ₃₈ O +Na ⁺ m/z = 317.2815, found: 317.2813.

Synthesis of 1 -Bromo-2-tetradecylcyclohex-1-ene

To an ice cooled solution of 3.0 g (10.2 mmol) 4-ferf-butylcyclohexanone in 10 ml methanesulfonic acid 1 .50 ml acetyl bromide (2.50 g, 20.4 mmol) were added drop wise. Stirring was continued for 2.5 h in an ice bath. The mixture was poured in 100 ml ice cooled 10 % NaOH solution and extracted with 100 ml ethyl acetate. Organic layer was washed with 50 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane. Yield: 2.0 g (5.60 mmol, 54.8 % d. Th.) colorless liquid, C ₂ oH ₃₇ Br (357.4 g/mol).

R _f (cycolhexane/ethyl acetate 9:1 ) = 0.88

¹ H-NMR (CDCI ₃ ; 500 MHz): δ = 0.88 (t, J _f =6.9 Hz, J ₂ =6.9 Hz, 3H, CH ₃ ), 1 .26 (s, 23H), 1.36- 1.41 (m, 2H), 1.55-1.60 (m, 1 H), 1.62-1 .70 (m, 3H), 1 .78-1.94 (m, 1 H), 1.96-2.05 (m, 1 H), 2.08-2.10 (m, 1 H), 2.13-2.15 (m, 1 H), 2.48 (t, J _f =5.6 Hz, J ₂ =5.6 Hz, 1 H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 14.1 , 22.7, 25.0, 27.2, 29.4, 29.5, 29,5, 29.6, 29.7, 30.9, 31 .9, 36.6, 37.1 , 1 18.7, 136.3 ppm.

HRMS EI+ calculated for C ₂ oH ₃₇ ⁷⁹ Br m/z = 356.2079, found: 356.2079.

HRMS EI+ calculated for C ₂ oH ₃₇ ⁸¹ Br m/z = 358.2058, found: 358.2083.

EA calculated for C ₂₀ H ₃₇ Br: C 67.21 ; H 10.43; Br 22.36; found: C 67.20; H 10.45; Br 22.35.

Synthesis of (S)-terf-butyl 4-((ft)-hydroxy(2-tetradecylcyclohex-1-enyl)methyl)-2,2- dimethyloxazolidine-3-carboxylate

To a stirred solution of 128 mg (0.55 mmol) Garneraldehyde and 100 μΙ TMEDA in 5 ml THF at -78 °C a freshly prepared solution of 200 mg (0.56 mmol) 1 -bromo-2-tetradecylcyclohex- 1-ene and 0.33 ml (0.56 mmol) t-BuLi solution (1.7 M in pentane) in 3 ml THF was added drop wise. Stirring was continued for 1 h at -78 °C. The mixture was poured in 10 ml ice cooled water and extracted with three times with 10 ml ethyl acetate. Combined organic layer was washed with 20 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 260 mg slightly yellow oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 19:1-4:1. Yield: 13 mg (0.025 mmol, 4.7 % d. Th.) colorless solid, C _3i H ₅₇ N0 ₄ (507.8 g/mol).

R _f (cyclohexane /ethyl acetate 7:3) = 0.55 ¹ H-NMR (CDCI ₃ ; 500 MHz): δ = 0.95 (t, J _f =7.1 Hz, J ₂ =7.1 Hz, 3H, CH ₃ ), 1 .26 (s, 28H), 1.35- 1.67 (m, 22H), 3.66 (dd, J =7.2 Hz, J ₂ =8.9 Hz, 1 H), 3.81 (dd, J =7.1 Hz, J ₂ =8.9 Hz, 1 H), 4.51 (ddd, Ji=7.1 Hz, J ₂ =7.1 Hz, J ₃ =9.0 Hz, 1 H), 5.50 (d, J =9.1 Hz, 1 H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 14.1 , 22.3, 22.5, 22.7, 23.5, 24.7, 26.9, 28.4, 28.5, 29.3, 29.5, 29.7, 29.8, 31 .9, 33.5, 61 .9, 64.5, 74.3, 95.2, 126.1 , 136.4, 157.1 ppm.

HR-MS p ESI calculated for C ₃ iH ₅₇ N0 ₄ +H ⁺ m/z = 508.4360, found: 508.4363.

HR-MS p ESI calculated for C ₃ iH ₅₇ N0 ₄ +Na ⁺ m/z = 530.4180, found: 530.4183.

Synthesis of (1 ft,2S)-2-amino-1 -(2-tetradecylcyclohex-1-enyl)propane-1 ,3-diol

To an ice cooled solution of 13 mg (0.025 mmol) (S)-fert-butyl-4-((R)-hydroxy (2- tetradecylcyclohex-1 -enyl)methyl)-2,2-dimethyloxazolidine-3-carboxylate in 10 ml CH ₂ CI ₂ were added 0.3 ml trifluoroacetic acid drop wise. Stirring was continued for 1 h in an ice bath. The mixture was poured in 20 ml ice cooled 10 % NaOH solution and extracted with 10 ml CH ₂ CI ₂ . Organic layer was washed with 10 ml saturated NaCI solution and dried over Na ₂ S0 ₄ . Solvent was removed to give 10 mg colorless oil as crude product, which was purified by chromatography on silica gel eluted with cyclohexane/ethyl acetate 4:1 -0:1 to yield: 6 mg (0.016 mmol, 65.2 % d. Th.) colorless solid, C ₂₃ H ₄₅ N0 ₂ (367.6 g/mol).

R _f (cyclohexane /ethyl acetate 1 :1 ) = 0.1

[a] _D ²⁰ = - 2.3° (c = 0.10; chloroform)

1H-NMR (CDCI ₃ ; 500 MHz): δ = 0.88 (t, J _f =7.0 Hz, J ₂ =7.0 Hz, 3H, CH ₃ ), 1 .26 (s, 24H), 1.51 - 1.46 (m, 2H), 1.59-1 .67 (m, 4H), 1 .85-1 .87 (m, 2H), 1 .93-1.99 (m, 2H), 2.04-2.09 (m, 2H), 3.56 (m, 1 H), 3.61 (dd, J =4.1 Hz, J ₂ =10.9 Hz, 1 H), 4.04 (ddd, J =4.2 Hz, J ₂ =8.8 Hz, J ₃ =8.8 Hz, 1 H), 5.58 (d, Ji=8.8 Hz, 1 H) ppm.

¹³ C-NMR (CDCI ₃ ; 125 MHz): δ = 14.1 , 22.6, 22.7, 28.2, 29.3, 29.5, 29.6, 29.6, 29.7, 29.9, 31 .9, 33.5, 57.5, 62.6, 77.4, 124.8, 137.1 ppm.