Tne present invention relates Ό a novel process tor preparing polyazamacrocycles Background of the Invention

The role of polyazamacrocycles -i vaπous biomedical applications has i ncreased dramatical ly over the past few years and the tetraazamacrocyclic structure is becomi ng an i mportant bui ldi ng block for new pharmaceutical agents Additionally, polyazamacrocycles are excellent chelants which if available at a low cost could be used in various applications for forming chelates, such as for water treatment systems As a consequence, the tetraazamacrocycl ic structure is becomi ng a fundamental building block in these compounds In particular, 1 ,4,7, 10-tetraazacyclododecane ("Cyclen ")

Cyclen

has proven to be one of the most versatile intermediates used in lanthaniαe spec *,c agents which are assumi ng prominance in compounds used in diagnostic and therapeutic medicine For example, during recent years the increasing importance of paramagnetic lanthanide chelates as contrast enhancement agents (or contrast agents) for magnetic resonance imaging ("MRI ") nas resulted in the commercial introduction of two Cyclen based products (Dotarem ™ by Gueroet and Prohance ^™ by Squibb) Futhermore, numerous companies are engaged in cli nical trials involving potential contrast enhancement agents for M RI which are also based on the Cyclen structure The market for MRI contrast agents is projected to be about US$700 million by 1998 (Frost & Sullivan, 1994) and Cyclen based Droducts are exoected to occuoy an imDortant position i n this market

At the present ti me Parπsh Chemical Co is the only adve ^r tise bulk sjppher of Cvc'en (as the tetraazahydrochioπαe salt), currently quoti ng a or ce o - J5S6 800/pound This once reflects the difficulty associated with the currently practiced synthetic method to make Cyclen

Current methodologies for the synthesis of Cyden dude: J . E Ricnman, T.J. Atkins, J. Am. Chem. Soc. 96. 2268-2270 ( 1974); and T. J. Atkins, J. E. Richman, W. F. Oettle, Org. Synth V!(collectιve volume), 58. 86-97 ( 1978). The currently practiced methodology for the synthesis of Cyclen [J. E. Richman, T

J. Atkins, J. Am. Chem. Soc. 96, 2268-2270 (1974)] involves a multistep protection-deprotection strategy as shown in the following Scheme A.

Scheme A

3 Ts— DETA (yield about 75-85%)

1) Add 1.5N NaOEt to reflux ethanolic solution

N 2) Filter off diNa salt under N ₂ and dry

(3) 3 Ts— DETA 2 a + (yield about 85-90%)

Scheme A Cont ' d

ine

Diethanolamine, (4) (yield about 75%)

\

H

(6)

(yield about 60%)

The conventional synthesis of tetraazamacrocyclic ligands involves the reaction of two segments of the target macrocycle in a polar, aprotic solvent, with the most used methodology being the Richman and Atkins' synthesis [J.E Richman, T J Atkins, J. Am Chem Soc. 96, 2268-2270 (1974)] In this procedure, one precursor is a preformed salt of a tπtosylamide and the other precursor contains sulfonate esters as the leaving groups (See Scheme A above ) method has Deen the one most cited in the literature to prepare saturated po'yazamacrocyies containing 3-12 nitrogen atoms

- nai isolation of the macrocycle requires narsh conditions to remove the Drotecting groups (e g tosyl or methanesulfonyl groups) These conditions involve either the use of 97% suifuπc acid or 33% HBr, acetic acid and phenol ^" his methodology is adequate, provided that great care is dedicated to the use of very pure, dry starting material ^τ he overall Drocess is tedious, time consuming, low yielding (~20-30% baseα on the starting amme) and an aoundace of tosylate or mesylat'e salts are

generated as waste Clearly *hιs descπoed Drocess is time consuming and cost y to make commercial quantities of the desired comDound

Another approach which has been tried towards the synthesis of large polyazamacrocycles (meani ng those having at least a 14 membered ring) has been the use o ^f metal ion promoted (template) reactions, developed in the early 1960's Many polyazamacrocycles i n thei r complexed form have been obtai ned by condensi ng glyoxal and a polyamine in the presence of a metal ion, mainly Nι(ll) and Cu( H) The metal ion can aid i n one of two ways ( 1 ) complex and sequester the polyazamacrocyoic product from the reaction equili brium mixture (in this way the formation of a macrocycie is promoted as its metal complex), or (2) the metal ion i nfluences the steπc course of the condensation such that formation of the cyclic product is facilitated [A Bianchi M Micheloni . P Paoletti , Coor Chem Rev 1 10, 17 (1991 )] Regardless of how the metal ion functions the application of such chemistry to the synthesis of thi rteen-membered (or less) polyazamacrocycles has not been successful, probably due to the incompatibil ity of the metal size and the eventual cavity size of the desired macrocycle

Previous synthesis of derivatives of 1 , 1 '-(1 ,2-ethanedιyl)-b/s[4,5-dιhydro- 1 H]- imidazole include

Chem Abst 100( 13) 102774f (Romanian Patent, RO 79987 B, 30 September 1982) which discloses alkyl derivatives, Chem Abst 58 2456a Belgian Patent 613,063, 1 5 February 1962 to Armour & Co which discloses other alkyl derivatives, and

WO 92/22535, publ ished 12 December 1992, which discloses additional al kyl derivatives

A citation which incorrectly indicates that 1 , 1 '-( 1 ,2-ethanediyl)-b/s[4,5-dihydro- 1 H]-ι mιdazole was prepared is

Chem Abst 1 19( 18) 194377x, however, the Citation, Z Anorg Allg Chem

619(7), 1 183-95 ( 1993), from which the aostract was done actually the closest compound descriDed and made was 1 ,2-bιs(2-ιmιdazolιne-2-yl)ethane

Clearly, it would be advantageous to have a cheaper 'ess time consuming process to make the desired polyazamacrocycles Some of the ways by which these results could be attained are bv using less costly starting materials not requi ring the Richman-Atkins protection- deprotection method [J Am Chem Soc 96, 2268-2270 (1974) and Org Synth volume), 58, 86-97 ( 1978)], and by increasing the overall yield of the process

~he present invention concerns a novel process for preparing polyazamacrocyc'es ' rom imidazolmes The present process employs novehmidazo ne intermediate compounds sucn as 1 1 '-(1 ,2-ethanedιyl)-bιs-[4,5-dιhydro- 1 H]-ιmιdazole The process ot this invention utilizes imidazolmes in a manner which allows for the use ot inexpensive or readily avanaole starting materials does 21 ^r eαuιre tne Richman-Atkins protection-deprotection method 'J

Am Chem Soc 96, 2268-2270 (1974) and Org Synth v_l(collectιve volume), 58, 86-97 (1978)], and increases the overall yield of The polyazamacrocycie product Specifically, the present invention concerns a process for preparing polyazamacrocycie compounds of the formula

where each n is independently 2 or 3,

m is 0 or an integer from 1 to 3,

sisOor 1,

y isOor 1,

with the proviso that at least 2 of s, y, and z must be 1 ,

Qιs-CH _r ,-C(0)-or-CFR,

R is hydrogen, C--Ce alkyl, -CO:H -C0 ₂ (Cι- 6 alkyl) or phenyl,

R ¹ is hydrogen, -C0 ₂ H, -C0 ₂ (C -C ₆ alkyl), Cι-C ₆ alkyl, C .-C ₆ alkyl substituted by NH ₂ , N0 ₂ , isothiocyanato, semicaroazido, thiosemicarbazido, maleimido, bromoacetamido or OR ² , phenyl or pnenyl substituted by NH ₂ , N0 ₂ , isothiocyanato, semicarbazido, thiosemicaroazido maleimido, bromoacetamiαo or OR ² or

R and R ¹ can be taken together to form a pnenyl or phenvi substituted bv NH ₂ , NO ₂ , isothiocyanato, semicarbazido, thiosemicarbazido, maleimido, oromoacetamido or OR ² , ano

R ² is hydrogen or C .- alkyl, which comprises reacting an alkylenepolyamine with a formyl equivalent, such as DMF dimethylacetal, either neat or in a nonaqueous solvent to form the unsubstituted imidazolme (9) of the formula

(

(9)

wherein q is independently 2 or 3,

followed by reacting (9) with:

5 (A) 1 equivalent of an ethylene oxide or an ethylene carbonate, in an aprotic solvent, to form an alcohol (16) of the formula

wherei n Q, S, R and R ¹ are αe'. neα as for Formula (I) and the dotted line represents the ootioπai presence oτ a oond ; when tne oond is present, then t is O, q is 2 to 3, and p is 1 ; wnen the oond is aosent, then wnen t is 0, q is 4 or more and p is 1 , when t is 1 or more, q is 2 or more and p is 1 , followed by intramolecular amination to form (17 of the formula

5 wherein the various terms are defined as for (16) and X is an anion, e.g., a halide ion; and then either basic or acidic hydrolysis to form a compound of Formula (I); or

(B) an electrophl ic substrate, i n a polar solvent, optionally in the presence of a non-nucleophilic oase. such as potassium carbonate to form (17 of the formula 0

0

5

wnerem Q, s, R and R are defined as for Formula (I), < ,s an anion, and the dotted line represents the presence of a bond, t is 0, q is 2 to 3, and o is 1 and then basic hydrolysis to form a compound of Formula \), or

(C) an electrophlic substrate, in a polar solvent, optionally in the presence of a non-nucleopnmc base, such as potassium carbonate, to form (17 of the formula

wherein Q, S, R and R ¹ are defined as for Formula (I), X is an anion, and the dotted line represents the presence of a bond, t is 0, q is 2 to 3, and p is 1 ; _Q followed by prolonged heating in a polar solvent or by treatment with a peroxide solution to form (IjJ) of the formula

wherein Q, S, R and R ¹ are defined as for Formula (I) and the dotted lines represent tne presence of a double bond, t is 0, q is 2 to 3, and p is 1 ; followed by basic hydrolysis to form the urea (19) of the formula 5

wherei n Q, s, and R ¹ are defined as for Formula (I) and t is O, q is 2 to 3, and p is 1 , and then basic hydrolysis under pressure to form a compound of Formula (I), and separating the desired polyazamacrocycie, / e by recrysta zation from an aqueous basic solution

15

In the present process to synthesize functiona zed and nonfunctionalized polyazamacrocycles of Formula (I) from ethyleneamine derived imidazolmes, for example, Cyclen ( 1 ,4, 7, 10-tetraazacyclododecane) was prepared by initially alkylating 1 , 1 '-( 1 ,2- ethanedιyl)-b/s[4 5-dιhydro- 1 H]-ιmιdazole (derived from TETA) with an appropriate Q electrophi l ic substrate, followed by base hydrolysis to provide the desired Cyclen of Formula (I) Application of this chemistry can be utilized to synthesize polyazamacrocycles of Formula (I) by the fol lowing general methods Defi nitions

Various terms used in the present application are defi ned as follows

25

"acidic hydrolysis" means standard hydrolysis conditions in an aqueous system at a pH below about 6 5, for example acetic acid, phosphoric acid, HO, HBr or H ₂ SO_. (usually from 10 to 20 eqs), usually at an elevated temperature, e g , a temperature from about 50 to about 120°C, preferably from about 80 to about 120°C

30

"C ^« -Ce al kyl " means straight and branched chained alkyl such as methyl, ethyl, prooyl , iso- propyl , tert-bu tyl (t-outyl), n-hexyl, and i ncludes C- - alkyi

"alkylenepolyamme" means C2-C18 al kylene N2-N6 polyamme, preferred are C2-O 0 alkylene -, _c N2-N4 poivamme more preferred are Ce, alkylene N ₄ polyamme ^* or example EDA, tπethylenetetraamine (TETA), N,N'-b.s(2-amιnoethyl)-1 ,3-propanedιamιne, N,N'-b.s(3- ami nopropy -ethvieneoiamme, c ιethyleπet ^r ιamιne (DETA), pentaethylenenexaamine or tetraethvieneoentaam e

"ambient temperature" means room temperature or a temperature from about 20 to 26°C

"aprotic solvent" means a non-nucleophilic solvent havi ng a bon ng poi nt range above ambient temperature, preferably from about 25 to about 190°C, more preferably from about 80 to about 160°C, most preferably from about 80 to 150 ^C C, at atmospheric pressure Exampes of such solvents are acetonitπle, DMF, diglyme, THF or DMSO

"basic hydrolysis" means standard hydrolysis conditions in an aqueous system, at a pH above about 7 5; for example aqueous NaOH or KOH (usually from 3 to 20 eqs), usually at a temperature from about 0 to about 200°C, preferably from about 25 to about 105°C, with process steps (A) and (B) described above preferably from about 90 to about 100°C, with process step (C) above to urea (19 at about ambient temperature, preferably from about 25 to about 100°C

"basic hydrolysis under pressure" means the use of a presure vessel (such as an autoclave at about 120 psi or a Paar bomb) under the other conditions for basic hydrolysis as defined above, such that the temperature for the hydrolysis is maintained at an elevated temperature, e.g , from about 1 50 to about 210°C, preferably from about 190 to 210°C

" DETA" means diethylenetπamine

"diglyme" means 2-methoxy ethyl ether

"DMF" means N,N-dιmethylformamιde

"EDB" means ethylenedibromide or 1 ,2-dιbromoethane

"EDC" means ethylenedichloπde or 1 ,2-dιchloroethane

"electrophilic substrate" means an organic compound having 1 or 2 electrophilic centers (on carbon atoms) where nucleoohilic agents (an amine, primary, secondary or tertiary) can react and contai ns the R, R ¹ and X terms Examples of such electrophilic caroon centers for substrates are vicinal substrates such as where the C ₂ -C ₄ alkylidine is substituted with at least two electrophil ic groups selected from halogen (Cl , Br, I), suifonates sucn as toluene sulfonate. methane sulfonate or tπfluoromethane sulfonate, eoihalohydπn such as epichlorohydπn or epibromohydrin, ^* ,3-dιhaιoacetone such as 1 ,3-dιchloroacetone, oxides such as ethylene ox'de or ethylene carbonate, or tosvates, mesyiates or tπflates oτ ethylene glycol Preterreo

compounds as the substrate i ncl ude C -C4 al kylidine (e g the ^* 1 - or 1 ,2-ethyl ιdιne or ethyiene oxide) substituted with two dielectrooh c moieties (e g di bromo or dichloro groups), such as 1 ,2-dι bromoethyl ιdιne

"elevated temperature" means a temperature above ambient temperature, e g , from about 30 to about 1 50°C, preferably from about 60 to about 125°C

" EO" means ethylene oxide

"formyl equivalent" means any compound capable of behaving like a formyl moiety [-C(0)-H] under the described process conditions, examples of such compounds are DMF, formic acid formic acid esters, N,N-dιmethylformamιdedιalkylacetals, tπalkylorthoformates, bromoform chloroform, lodoform, N,N-dιalkyl formamides or tπ halomethyl acetaldehyde The "dialkyl " term includes C 6 alkyl groups that are either straight or branched chained alkyl groups Preferred formyl equivalent compounds are DMF and dι(C . -C ₆ alkyl)acetals

"intramolecular amination" means formation of a carbon to nitrogen bond where the carbon and nitrogen are i n the same molecule [/ e , J March, Advanced Organic Chemistry, 3rd ed , John Wieley & Sons, ( 1985), p 423]

"non-aqueous solvent" means any organic solvent contai ning less than 3% water, such as DMF, diglyme, and acetonitπle

" non-nucleophi lic base" means a base which does not act as a nuceolphile in the reactions with the reagents or compounds of this invention, for example, alkali metal carbonates such as potassium carbonate, cesium carbonate, sodium carbonate, or bicarbonates such as sodi um bicarbonate A preferred base is potassium carbonate

"PEHA" means a mixture of pentaethylenehexaamme isomers containing greate ^r than 30% of the linear isomer

"peroxide solution" means dilute (about 1 - 10% w/w) aqueous hydrogen peroxide or aqueous peracids, such as oeracet c acid, or derivatives which are capable of releasing peroxide unoer the reaction conditions, e g , 10% aqueous H2O2

"polar solvent" means a solvent which has a dipole moment (ε) of 2 9 or greater, such as DM F, THF, ethylene gy col dimeth l ethe ^r DMSO, acetone, acetonitπle, methanol, ethanol , isopropanol, n-prooanol , t-butanol or 2-methoxyethyι ether ^D reτerred solvents are DM F

diglyme, and aceτonitπie

"polar, aprotic solvent" means a polar solvent as defined above which has no available hydrogens to enchange with the compounds of this invention during reaction, for example DMF, acetonitrile, diglyme, DMSO, or THF.

"polyazamacrocycie" means a macrocyclic ring having from 3 to 6 nitrogens present in the backbone of the ring, the other members of the ring are carbon, oxygen, sulfur and silicon, but are preferably carbon.

"prolonged heating " means maintaining a temperature range of from about 80 to about

200°C for from about 4 to about 48 hours.

"TEPA" means a mixture of tetraethylenepentaamine isomers containing greater than 40%) of the linear isomer.

"TETA" means a mixture of triethylenetetraamine isomers containing greater than 50% of the linear isomer which is triethylenetetraamine, (7), and has the structure

The following compounds and formulas are defined :

"Cyclen" means 1 ,4,7, 10-tetraazacyclododecane, (6), a compound of Formula (I), and has the structure

"EDA" means ethylenediamine, (8), and has the structure

H ₂ N NH ₂ (8)

' 1 , 1 '-(1 ,2-ethanediyl)-b/ ^' s[4,5-dihydro-1 H]-imidazole", (9a), and has the structure

" 1 ,2-ethanyl-2-[4,5-dihydro-1 H]-ιmιdazole", (10), and has the structure

„

DETA" means diethylenetπamine, (1), and has the structure

'TEPA" means tetraethylenepentaamine, (1_1), and has the structure

NH ₂

"1,1'-(2,2'-diethylamine)-bis[4,5-dihydro-1H]-imidazole", (12),and has the structure

'PEHA" means pentaethvienehexaamme, (13), and has the structure

10 ' 1 ,2-ethanediyl-bis(1 ,2-ethanyl-2-[4,5-dihydro-1 H]-imidazole), (14), and has the structure

15

20

25

30

35

The present invention or prepari ng the compounds of Formula (I) utilizes imidazolmes as the key, critical substrate prior to the formation of the polyazamacrocycie oτ Formula (I) The reason that these imidazolmes are well suited for this chemistry is twotold once formed, the nitrogen bearing the double bond experiences enhanced nucleophilicity This attribute is a direct result of the lone pair of electrons found on the adjacent nitrogen

(note the resonance structure possi ble of the b.s-imidazolme derived from TETA) Secondly, the secondary amines of the starting TETA (7) are now protected from reacting with the electrophil ic substrate

The approach of the present invention taken towards the synthesis of this class of polyazamacrocycl ic compounds of Formula (I), reported herei n, is the reaction of an imidazolme (9) with an electrophilic substrate These i madazolines (9) are prepared by reaction of an alkylenepolyami ne with a formyl equivalent, (/ e , N,N-dιmethylformamιde dimethoxy acetal) which yields the imidazolme (9) upon heating (about 50 to about 100°C) either neat or in an organic solvent (e g , toluene, diglyme, xylene, DMF, THF, acetonitπle, 1 ,4-dιoxane, diethyl ether, hexane, heptane or octane) The by-products from this formamide acetal reagent are the appropriate alcohol (/ e , CH ₃ OH) and dimethylamine

After cydization, removal of the protecting groups on the secondary amines (e g , Scheme II) is easily performed by base hydrolysis ^τ hus, the use of expensive protecting groups, harsh deorotection conditions, and the expensive disposal of by-product salts from the prior art procedures can oe avoided As a result, the number of mani bulations required to synthesize polyazamacrocycles by the process of this invention (vs the conventional azamacrocycle sysnthesis) is minimal

Generation of the imidazolmes can be performed a variety of ways, e g , by treating the appropriate C ₂ -Cς alkyleneamine (1 e , ethyleneamine) with a formyl equivalent [such as DM F under autoclave conditions (t = > 1 50°C)]

Treatment of the resulting imioazoh ne (9) with a electrophilic substrate yields a polyazamacrocycie intermediate, / e (17) With, for example, use of a electrophilic substrate, it is believed that the nucleophilic imidazolme nitrogens displace the electrophilic moieties directly to yield, for example, (17) Upon basic hydrolysis for example, of (12) yields the polyazamacrocycie compound of Formula (I), for example Cyclen (6) When this approach is taken, no appreciable by-products are noted Only the polyazamacrocycie of Formula (I) and recovered starting material alkylenepolyamine are isolated

With the use of ethylene oxide, once again the nucleophi l ic imidazolme nitrogen ooens the ethylene oxide to yield Q6J Intramolecular amination of (16) yields (17) which is then hydroyzed under basic conditions to provide Cyclen (6)

While not wishing to oe bound by theory, it is believed that the advantageous results of the present i nvention are obtained because oτ intramolecular reactions as shown in the following Scnemes Scnemes , il and I are reoresentative oτ the compounds of Formula (I)

- ' 6-

and although directed to only one group of such compounαs can be used to prepa ^r e tne othe ^r groups within Formula (I)

Scheme I Preparation of Nucleophilic Intermediates

Equation A

Equation

/ 50-100°C

H ₂ N N \. ^" \

NH ₂ + (CH ₃ ) ₂ NCH(OR) ₂ N N NH ₂

H

DETA, (1) (10)

Equation C

Equation D

(8) (15)

Scneme I Cont'd Preparation of Nucleophilic Intermediates

Equation E

(14) (13)

Equation F

where s is 0 or 1 MR -

OH

R XX R- where s isO

Scheme I Preparation of Azamacrocycles Containing 3-6 Nitrogens

Equ

) intramolecular amination

(16a) (17a), X- = OH; R = R1 =H

Equation D

Equa

R R ^J

2(15) \ _n 80-160°C — 7a)

X DMF oracetonitrile (1 κ ₂ C0 ₃ where s is 0 or 1

Eαuation F

/ R ^J 80-160°C

2 (8) + 2 / DMForacetonitrile (17a)

X \ K ₂ C0 ₃ where s is 0

Equation G

Eq

Equation I

(9 )

w

Equation J (20a) OH

Equa

Equ

Scheme III Preparation of Pure TETA

(9a) (Z)

When the polyazamacrocycie of Formula nas Q equal to -C(O)-, the compounαs

are generally prepareα as :n Scneme 'V below Aitnougn oniy one group of compounds of Formula (I) is shown in this Scheme ιV, the other groups of compounds of Formula (I) can be prepared in a similar manner

Scheme IV

(9a) + ^" Cl-CH,-C(0)-CH--Cl

polar solvent e.g. DMF or acetonitrile

40-100°C

f Formula (I)

In the above Schemes tne various ^* erms are defineα as for Formula (I) above Detailed Descri pti on of Scheme . and H in the aoove Schemes, the general process description illustrates specific steps that may be useα to accomplish a desi red reaction step The general descri ption of these process steps fol lows

Synthetic Scheme I above depicts the synthesis of the starting materials and begi ns with the formation of the imidazolmes (9a), (10), (12), (1_4) and (15) The appropriate al yleneami ne [/ e , triethylenetetraamine for (9a), diethylenetπamine for (lOj, TEPA for (1_2), PEHA for (14) and ethylenediamine for (1_5)] is either dissolved i n a solvent [e g . toluene, benzene, hexane, diglyme, diethyl ether, THF, acetonitπ le, dimethylformamide (DMF)] or reacted neat with the next reagent The N,N-dιmethylformamιde dimethyl acetal [2 equivalents (eqs)] is added to the sol ution at room temperature Tne solution is then heated at about 50 to about 1 10°C, preferably from about 60 to 100°C (Equation A-D) After 15-30 minutes (mins) at an elevated temperature, the heat is removed and the solution is allowed to reach room temperature (about 20 to about 25°C) The solvent, if present, is then removed by vacuum distillation The resulting i midazolmes can be purified using standard procedures, such as through recrystal lization or distillation

Other methodologies for the synthesis of imidazolmes known to those skilled in the art also could be utilized For example, the condensation of formyl equivalents under reaction conditions in the Scheme II will also yield the imidazol mes

Further treatment of (9) with 1 eq of ethylene oxide (or ethylene carbonate which is an ethylene oxide equivalent) in a polar, aprotic solvent (e g , DMF, diglyme) at 120- 160°C for 4-10 hours (hrs) yields (16a) (Equation E) No further purification is performed

In Scheme II, polyazamacrocyclic compounds are prepared using polar, aprotic solvents, such as those outlined for Scheme I, (e g , DMF, diglyme, acetonif-ile), the compou nds of (9a), (10), (12), (14) or (15) as the nucleophilic species, and an ethylene oxide or an ethylere carbonate as the electophilic substrate This method results in the formation of an intermediate [/ e , (16a) Scheme I, Equation E] Intramolecular aminat on of this intermediate results in the formation of a polyazamacrocycie, / e Scheme II, Equation C, (17a) Hydrolysis of this intermediate t e (17a), with 3- 1 5 eq of aqueous NaOH yields the "free" polyazamacrocycie (Equations A, H, J, K, L, M, N ana O) using a vici nal 1 ,2-dιhalo substrate as the electrophilic substrate in forming the

polyazamacrocycie is accom pl ished, for example, Dy treati ng (9) with 1 ,2-αιbromoetnane (or 1 ,2-dιchlorethane) i n a polar solvent, in the presence of non-nucleophil ic base (Equati on B ) After 0.5-5 hrs at aoout 60- 120°C, the solvent is removed by distillation yielding a polyazamacrocycie intermediate, i.e. (17), which is hydroiyzed i n 3-8 eq of refl uxi ng aqueous NaOH (10-50% w/w), yielding the free polyazamacrocyclic (Equations G, H, J, K, L and M) ami ne of Formula (I). The resulting tetraazamacrocycle is isolated by standard procedures, i.e. recrystalization from an aqueous basic solution.

The preferred order of addition for the synthesis of (17) involves addi ng a DMF or acetonitrile solution contai ning EDB and (9) at room temperature to a heated sol ution of K ₂ C0 ₃ i n DMF or acetonitrile The hydroysis is then conducted as described before The advantage of this modification is that a higher conversion of (9) to (12) is achieved Although not as desireable, all reactants can be combined at one time in DMF or acetonitri le and then heated.

Alternatively, (17) can be converted to (18) either by prolonged heati ng or by treatment with a peroxiαe sol ution (Equation D). Conversion of (18a) to (19a) is accomplished by treatment under basic hydrolysis conditions (Equation G). Cyclen (6) is formed from (19a) by basic hydrolysis under pressure. Detailed Description of Scheme IV

In Scheme IV the cyclized ketone intermediate (25) is prepared by simultaneous additions of 1 ,3-dichloroacetone and (9a) to an acetonitrile/K ₂ C03 slurry. The resulting cyclized product can then be hydroiyzed under basic hydrolysis conditions to provide (26).

The synthesis of dialkyl derivatives of 1 , 1 '-( 1 ,2-ethanediyl)-b.s[4,5-di hydro- 1 H]- imidazole is reported [Chem. Abst. 100(13) : 102774f (Romanian Patent, RO 79987 B, 30 September 1982); Chem. Abst. : 2456a Belgian Patent 613,063, 15 February 1962 to Armour & Co.] by treating TETA with a long chain fatty acid at high temperatures. The present invention provides the first obtaining of an unsubstituted 1 , 1 '-( 1 ,2-ethaned iyl)-b.s[4,5-di hydro- 1 H]- imιdazole (9a) from the quaπtative reaction of TETA and N ,N-αιmethyiformamιde dialkyl acetals.

All other starting materials are either purchased commercially or made by known processes.

The polyazamacrocycles of Formula (I) prepared by the process of this i nvention are important as intermediates for making derivatives useful in various medical applications, such as magnetic resonance imaging (diagnostic) where a derivative of Cyclen with Gd ^{* 3} is useα, e.g. the hydrogens of Cyclen (N-H) are replaced with methylenecarboxylates (e.g., 1 ,4,7, 10-tetraazacyciododecane- 1 ,4,7, 10-tetraacetιc acid (DOTA), US Patent 4,639,365) ; therapeutic nuciear medicine where 1 ,4,7, 10-tetraazacyclododecane-1 ,4,7, 10- tetramethylenepnosononic acid (DOTMP) is complexeα with rare earth nuciides for del ivery of the nucnαe to oone ^τ' or re ef of oone pai n, tumor regression or oone marrow supression (e. g. ,

US Patent 4,976,950), i n anti boαy (e g monoclonal anti bodies) del ivery systems as a cheiate τo ^r the metal ion [J Am Chem Soc JJ_0 6266-6267 ( 1988)] ana i n in vivo and in vitro den ve ^r y systems tor diagnosis or therapy applications

Also the present polyazamacrocycles of Formula (I) are chelants capable of forming chelates when used for water treatment These polyazamacrocycles can also be used as a non-hypochloπte bleach (e g , see European 0458 397)

The invention will be further clarified by a consideration of the following examples, which are intended to be purely exemplary of the present invention

General Experimental

The reactions were analyzed by gas chromatography (GC) on a HP-5890A instrument The column employed was a HP-Ultra- 1 , 50 m x 33 m The temperature program was: Initial Temp 60°C for 10 mm, the rate of temperature increase was 10°C/mιn up to 270°C The final temperature was held for 15 mm All percentages are in weight percent unless stated otherwise

TETA was obtained from The Dow Chemical Company's ethyleneamine TETA isomer stream

Al l other reaction reagents were obtained from commercial suppliers and used as received without further purification or purified prior to use NMR spectra were recorded on a Bruker AC-250 MHz spectrometer equipped with multi-nuciear quad probe ( 1 H and 13C) at 297°K unless otherwise indicated and measured as parts per million (ppm) 44

PREPARA ON OF STARTING MA ^T ERIALS

Example A Preparation of 1 ,2-Ethanyl-2-[4,5-dιhydro-1 H]-ιmιdazolιne, (10)

To a stirring solution of 10 g (00097 mol) of diethylenetπamine (DETA) was added in one portion, 125 g (00097 mol) of N,N-dιmethylformamιαe dimethyl acetal, at 20 to 25°C The solution was then brought to reflux (60-65°C) The cooled solution was stripped of methanol and dimethylamine via rotoevaporation leaving a light yellow oil Further distillation of the oil provided 084 g, yield of 73%, of the desired product, which is represented by the formula

10

\X \

N N NH ₂

(10)

Example B Preparation of 1,1 '-(1,2-Ethanedιyl)-bιs[4,5-dιhydro-1H]-ιmιdazolιne, (9a), using a solvent

To a stirring solution of 500 mL of toluene and linear TETA (100 g, 068 mol) was added 94% pure N,N-dιmethylformamιde dimethyl acetal (173.37 g, 136 moi) ^τ he solution

20 was refluxed for 30 mm The toluene was removed via rotovap The resulting light yellow solid which was filtered and rinsed with THF The resulting white solid was isolated in 92% yield (104 g, 063 mole), mp 107-9 C and further characterized by 1H NMR(CDCI3)

-> 67 (s, 2H), 37 (t, 4H), 31-32 (ove ^r lapping signals, 8H);

25 13C MR(CDCI3) δ 1572 (CH), 550 (CH2), 484 (CH2), 464 (CH2); and Mass Soec m/e 167 (M + 1, 1), 166(6, 83 (100), 56(89) The product is represented by the formula

30

(9a)

Example C Preparation of 1 1 '-( 1 ,2-Ethanedιyl)-bιs[4 5-d ι hyαro- ' Hl-ι mιdazoιme (9a) from

TETA, without a solvent

A Preparation of 1 , 1 -( 1 ,2-Ethanedιyl)-bιs[4,5-dιhydro- 1 H]-ι mιdazo!e (9a) from TETA

The TETA (253 g, 1 73 mol) was added to 94% pure N-dιmethyιformamιαe dimethyl acetal (307 03 g, 2 42 mol) As the solution was warmed to 65°C wιth stirri ng, methanol was liberated The solution was heated for 20 mm at 65°C The methanoi and dimethylamine were stripped using a rotoevaporator The bis-imidazoline was crystallized from the oil by treating the oil with a 50 50 (v/v) mixture of ethylacetate and cyclohexane The resulting precipitate was filtered The filtrate was reconcentrated and the above procedure repeated until no more bis-imidazloine preci pitated from solution The overall yield of the bis- i midazoline (9a) was 133 g (66% based the DMF acetal) The product is represented by the formula

( 9a )

B Preparation of cyclized intermediate ( 17a)

To a vigorously stirring mixture of K2C03 (0 72 mol) in 1 L of DMF at 100°C w added a 1 3 L DMF solution containing both (9) (104 g, 0 63 mol) and 1 ,2-dιbromoethane ( l o5 g, 0 88 mol) Upon completion of the addition ( ^" 30 mm), the resulting solution was heateα tor an additional 30 mm at 100°C After cooling to 50°C, the K2C03 was filtered and the resulti ng filtrate was concentrated to dryness The crude cyclized salt was washed with acetone to ' ^• emove the trace impurities The isolated yield of ( 17a) was 99% (171 g, 0 62 mol) and cnaracte ^rι zed by 13C NMR (CDCI3)

6 162 0 (C), 72 7 (CH), 54 2 (CH2), 52 4 (CH2), 45 5 (CH2), 44 3 (CH2) The proαuct is represented by the formula

( 17a )

Example D: Preparation of (18a).

The procedure used for the synthesis of (17a) was followed using 1.14 g (6.8 mmol) of (9) except that the DMF solution was heated for 12-14 hours at 100 ^C C. The cooled solution was stripped to dryness leaving an amber colored solid. No further purification of the material was performed The compound is characterized by: 1 H NMR (D20) δ 4.3 (s), 4 0 (s); and 13C NMR (D20) δ 46.3 (CH2), 54 3 (CH2), 150.6 (C). The product is represented by the formula:

( 18a )

Example E Preparation of ( 18a) via Hydrogen Peroxide

The cyclized intermediate, (17a), (1 g, 3.6 mmoι) was αissolveα in 10 mL of water

A 10% H202 was added to the solution. The solution was heated to reflux. After 30 mm, the heat source was removed and the solution was carefully stripped to dryness No further purification of the material was performed. The product is represented by the formula:

( 18a )

Example F Preparation of 4,5-Dιhydro-1 H-ιmadazole, (15)

EDA (50 g, 0 83 mol) and DMF-dimethoxy acetal (52 8 g, 0 42 mol) were placed into a round bottom flask and warmed to 65-70°C After 30 mm the heat source was removed and the methanol and dimethylamine were removed by rotoevaporation The excess EDA was then removed by distillation Final purification of 4,5-dι hydro- 1 H-ιmιdazole was achieved by distillation (62-64°C, 2mm Hg) The isolated material was obtained in a yield of 20 5 g (70%) and is represented by the formula

(15)

Example G Preparation of 1 , 1 '-( 1 ,2-ethanedιyl)-bιs[4,5-dιhydro-1 H]-ιmιdazolιne, (9a)

4,5-Dιhydro-1 H-ιmadazole (0 5 g, 7 1 mmol), prepareα in Example F, 1 48 g (1 1 mol) of K2C03, and 10 mL of DMF were placed in a round bottom flask, jnder nirogen The mixture was heated to 90°C, then a solution of 0 67 g (3 57 mmol) of EDB >n 5 mL of DMF was added dropwιse over 20 mm Heating was continued for an additional 30 mm The K2C03 was altered from the solution and the resulting filtrate was concentrated to αrvress ^" he resulting off white semi-solio was recrystallized from THF to yield 0 45 g (75%) of the title product ano is represented by the τormula

\ /

N N N

(9a)

Example H Preparation of a cyclized intermediate, (17a)

The 4,5-dιhydro-1 H-imidazole (0 5 g, 7 1 mmol), prepared in Example G, and 1 8 g (9 6 mmol) of EDB were dissolved in 10 mL of DMF This solution was then added drpwiseover about 20 mm to a stirring solution of DMF/K2C03 which was at 90-100°C Heating was continued fo an additional 1 hour The K2C03 was then removed by filteration and the resulting filtrate was concentrated to dryness The resulting semisolid was rinseo with acetone to yield (17a) as represented bv the following formula

X

( 17a )

Example I - Reparation of cyclized i ⁿ termediates, (25)

The imiαazoie (9a) (5 g, 30 mmol) and 4 2 g (33 mmol) of 1 ,3-dιchloroacetone were dissolved in separate 50 mL aiiquots of acetonitπle These solutions were then addeα simultaneously to a slurry of 5 g of K2C03 in 50 mL acetonitπle over a 10 mm period at 25°C After aαdition was completed, the solution was filtered and concentrated in vacuo to give, as a brown semi-solid, (25), as represented by the following formula-

PREPARATION OF FINAL PRODUCTS Example 1 : Preparation of Cyclen (6).

The cyclized intermediate [(17a), 1 13 g, 0.41 mol], prepared by the procedure of Example C, Part B, was dissolved in water to give a total volume of 450 mL and was added dropwise to a refluxing solution of 400 mL of NaOH (8 eq, 129 g, 3.3 mol) The solution was heated for an additional 30 mm after completion of the addition of the cyclized intermediate The aqueous caustic solution was filtered while hot and then the filtrate cooled to room temperature. The aqueous filtrate was then concentrated (rotoevaporator) until crystalline solid was observed in the solution After cooling, Cyclen was filtered and the process was repeated on the filtrate until no further crystallization occurred. The aqueous solution was then concentrated to dryness and the remaining precipitate removed by extractions of the solid residue with hot toluene. The overall yield of (6) was 88% (62 g, 0.36 moi) and characterized by:

1 H NMR (CDCI3) δ 2.54;

13C NMR (CDCI3) 545.9; and Mass Spec

m/e 173 (M + 1 ), ¹ 73 (2), 128 (8), 104 (45), 85 ( 100), 56 (80) The product is represented by the formula

( 6 )

Example 2- Preparation of (19a)

The cyclized intermediate (18a) (1 g, 5 2 mmol), prepared by the procedure of Example D, was dissolved in 15 mL of water The aqueous solution was added dropwise to refluxing solution of NaOH (5 eq, 1 04 g, 25 mmol). After being heated for 60 mm, the solution was cooled to room temperature and extracted with chloroform (4x20 mL) The resulting chloroform solution was dried over K2C03, filtered and stripped to dryness The resulting solid was not purified and characterized by 1 H NMR (CDCI3) δ 2 4 (br s, 2NH), 2 6 (m, 2H), 2 9 (m, 6H), 3 1 (m, 2H), 3 6 (m, 4H), 4 0 (m, 2H), 13C NMR (CDCI3) δ 42 0 (CH2), 44 9 (CH2), 45 8 (CH2), 49 6 (CH2), 165 9 (C), IR (CHCI3)

2998, 2932, 2895, 1675. 1496, 1455, 1265 cm-1 , and Mass Spec m/e 199 (M + 1 , 2), 198 (12), 155 (100), 142 (37), 126 (18), 1 13 (53), 99 (33), 85 (45), 70 (25), 56 (73)

The product is represented bv the formul

(19)

Example 3: Preparation of (16a).

The bis-imidazoline (9a) (1.12 g, 6.8 mmol), prepared by the procedure of Example B, and the ethylene carbonate (0.6 g, 6.8 mmol) were dissolved in 50 mL of anhydrous DMF. The resulting solution was heated to 140°C for 5 hours. The heat source was removed and the resulting solution was stripped to dryness. No further purification on the material was performed. The product is characterized by: 13C NMR (CDCI3) δ 42.9 (CH2), 44.9 (CH2), 48.4 (CH2), 50.6 (CH2), 51.4 (CH2), 52.7 (CH2), 58.3 (CH2), 60.1 (CH2), 75.1 (CH), 165 6 (C); and Mass Spec m/e 21 1 (M + 1 ) (3), 210 (21), 180 (32), 138 (100), 124 (26), 97 (25), 83 (12), 56 (31 ). The product is represented by the formula:

OH

Example 4 Preparation of Cyc'en, (6) in n-propanol

When tne procedure of Example C, Part B was repeated by adding an n-propanol solution containing 0 52 mL (6 mmol) of EDB and 4 5 mmol of (9a), prepared by the procedure of Example C, Part A, to a solution of 70 mL of refluxing anhydrous n-propanol containing 0 62 g of K2C03 and refluxed for 18 hrs, after removal of the solvent an amber residue remained which was dissolved in water and analyzed by 13C NMR to indicate that the major product was (17a) Basic hydrolysis of (17a) provided a 55% yield of (6) which was identical to that obtained using DMF in Example 1 The product is represented by the formula

Example 5 Preparation of Cyclen, (6) in ethylene glycol dimethyl ether

When the procedure of Example C, Part B, was repeated by adding an ethylene glycol dimethyl ether solution containing 0 52 mL (6 mmol) of EDB and 4 5 mmol of (9a) prepared by the orocedure of Example C, Part A, to a solution of 70 mL of refluxing ethylene glycol dimethyl ether containing 0 62 g of K2C03 and refluxed for 24 hrs, after removal of the solvent by decanting, an amber residue remained which was dissolved in water and analyzed by 13C NMR to indicate that the major product was (17a) Basic hydrolysis of (17a) provided a 50% yield (6) which was identical to that obtained using DMF in Example 1 The product is represented by the formula

Example 6 Preparation of Cyclen, (6) in acetonitrile

When the procedure of Example C, Part B, was repeated by adding a 60 mL acetonitrile solution containing 7 7 g (41 mmol) of EDB and 30 mmol of (9a), prepared by the procedure of Example C, Part A, to a solution of 61 mL of refluxing acetonitrile containing 4 0 g

of K2C03 and refluxed for 2 hrs after removal of the solvent by decanting, an amber residue remained which was dissolved in water and analyzed by 13C NMR to indicate that the major product was (17a) Basic hydrolysis of (17a) provided a 85% yield and was identical to that obtained using DMF in Example 1 The product is represented by the formula

Example 7 Preparation of Cyclen, (6) in diglyme

When the procedure of Example C, Part B, was repeated by adding a diglyme solution containing 0 52 mL (6 mmol) of EDB and 4 5 mmol of (9a), prepared by the procedure of Example C, Part A, to a solution of 61 mL of refluxing diglyme containing 0 62 g of K2C03 and refluxed for 9 hrs, after removal of the solvent by decanting, an amber residue remained which was dissolved in water and analyzed by 13C NM to indicate that the major product was (17a) Basic hydrolysis of (17a) provided a 85% yield and was identical to that obtained using DMF in Example 1 The product is represented by the formula

Example 8: Preparation of 1 ,4,7-trιazacyciononane in DMF

When tne procedure of Example C, Part B, was repeated using (10), prepared by the procedure of Example A, and alkylating with a vicinal dihalogenated ethane (EDB or EDC), followed by basic hydrolysis, there was obtained a 1 ,4,7-trιazacyclononane, which is represented by the following formula:

Example 9: Preparation of 2,3-dicarboxyltetraazacyclododecane.

When the procedure of Example C, Part B, was repeated using (9a), prepared by the procedure of Example C, and alkylating with 2,3-dibromosuccinic acid, there was obtained 2,3-dicarboxyltetraazacyclododecane, which is represented by the following formula:

(24)

H ₂ H

Example 10 Preparation of Cvclen (6) from (19a)

The urea (19a), 05 g (253 mmol), was dissolved in 50 mLof water To this solution was added 4 equivalents of NaOH (08 g, 50% w/w solution) The solution was then placed in a 300 mL Paar bomb and heated with stirring to 200°C After 3 hrs the reaction was allowed to cool The aqueous solution was then concentrated to the point of crystallization of Cyclen The product was then filtered and dried to yield Cyclen (6), having the same characterization data asm Example 1 The product is represented by the formula

15

:6)

Example 11 Preparation of (21a) from (9)

To a stirring mixture of DMF (10 mL)at 100°C was added a 15 mL solution of DMF 20 containing both 1 g (60 mmol) of the bιs-ιmιdazoiιne(9) and 09g (654 mmol) of the epibromohydrin (23) Upon completion of the addition (about 15 mm), the resulting solution was heated for an additional 45 minat 100°C After cooling to 50°C the solution was concentrated to dryness The isolated yield of the crude intermediate (20a) as a racemic mixture was 178 g, 99% The termediate is characterized by 25 13CNMR(D20)

51660, 1658,675,673,625,616,549,547,540,538 532,531,528,527,485,479,452,

442

The intermediate ,s represented by the formula

30

35

( 20a ) OH

The intermediate (20a) was hydroiyzed by basic hydrolysis to the product (21a). No further purification on the material was performed. The product is represented by the formula:

Example 12: Preparation of (26) from (25).

The cyclized intermediate (25), prepared by the procedure of Example I, was dissolved in 20 mL of water, then 10 mL of 50% NaOH was added. The solution was heated to 90 for 1 hour, then cooled and concentrated in vacuo to give (26) as a viscous yellow oil which is represented by the formula:

Although the invention has been described with reference to its preferred embodiments, those of ordinary skill in the art may, upon reading and understanding this disclosure, appreciate changes and modifications which may be made which do not depart from the scope and spirit of the invention as described above or claimed hereafter