CN1212693A - Process for preparing purine derivatives - Google Patents

Abstract

Process and novel intermediates for preparing the L-monovaline ester of 2-(2-amino-1,6-dihydro-6-oxo-purin-9-yl)methoxy-1,3-propanediol and its pharmaceutically acceptable salts. The present process and intermediates provide for reduced impurities in the mono-valine ester end-product, also eliminating the costly and time consuming purification step and allowing the use of starting materials of lower purity, which, in turn, reduces overall production costs. These products are of value as antiviral agents with improved absorption.

Description

The method for preparing purine derivative

The present invention relates to the preparation method of the prodrug formulation of ganciclovir and its pharmaceutical salts, particularly by 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl) methoxyl group-1, the preparation method of ammediol and its pharmaceutical salts deutero-L-L-valine ester.The new intermediate and the intermediates preparation that the present invention also relates to use in the aforesaid method.

English Patent 1523865 has disclosed the antiviral agent that has the purine derivative of no loop chain at 9.Methyl cellosolve has been proved has herpesvirus resisting activity with the derivative 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl) of INN called after acyclovir, as: the activity of anti-herpes simplex virus.

United States Patent (USP) 4,355,032 has disclosed compound 9-[(2-hydrogen-1-methylol-oxyethyl group) methyl] compound 2-(the 2-amino-1 of guanine or INN called after ganciclovir, 6-dihydro-6-oxo-purine-9-yl) methoxyl group-1, ammediol or 9-[(1,3-dihydro-2-propoxy-)-methyl] guanine (DHPG).Ganciclovir has the activity of herpes family virus efficiently, but anti-herpes simplex and cytomegalovirus.

UK Patent Application GB 2 122 618 has disclosed following 9-(2-'-hydroxyethoxy ylmethyl) guanine derivatives and its pharmaceutical salts of general formula:

Wherein X represents oxygen or sulphur atom, R ¹Representation hydroxy or amino, R ²Represent hydrogen atom or CH ₃OR ³ _a, R ³And R ³ _aCan be identical or inequality, be respectively amino acid acyl.These compounds can be in intensive polar solvent, as: dimethyl formamide or hexamethylphosphoramide, preferably have under the condition that alkali exists, guanine derivatives and side chain intermediate are carried out condensation reaction and prepare, or under strong acid condition, prepare by the thermal condensation reaction.These compounds can be used for treating virus infection, have high water-solublely, and this provides convenience for preparation medicine water soluble preparation.Though the general formula of this UK Patent Application contains general R ²Representative-CH ₃OR ³ _aCompound, but this group special compound does not disclose.

European patent application EP 0 375 329 has disclosed following preceding drug compound or its physiologically acceptable salt of general formula

Wherein R and R ¹Independently be selected from hydrogen atom and aminoacyl, condition is R and R ¹In to have one at least and represent aminoacyl, B represents following groups

R wherein ²Can represent C _1-6Straight chain, C _3-6Side chain or C _3-6Cyclic alkoxy, or hydroxyl or amino or hydrogen atom.These preceding drug compound very moments have superior bioavailability when obeying administration, thereby obtain the parent compound of high density in vivo.

European patent application EP 0 375 329 embodiment 3 (b) have disclosed the preparation method of two (L-Isoleucine) esters of the ganciclovir of white foam shape, embodiment 4 (b) has disclosed the preparation method of two (glycine) esters of the solid ganciclovir that is white in color, embodiment 5 (b) has disclosed the preparation method of two (L-Xie Ansuan) esters of the ganciclovir that is solid shape, and embodiment 6 (b) has disclosed the preparation method of two (L-L-Ala) esters that are melicera ganciclovir that contain 90% dibasic acid esters and 10% monoesters.The preparation method of dibasic acid esters is: will select the amino acid or the suitable amino acid and the ganciclovir of function of protection to react; This reaction can be carried out by conventional methods, for example in pyridine dimethyl formamide equal solvent, as 1, under the existence of coupling agents such as 3-dicyclohexyl carbodiimide, carries out in the presence of alkaline catalysts such as 4-dimethylaminopyridine selectivity.Above-mentioned dibasic acid esters is an amorphous substance, is difficult to make oral Pharmaceutical dosage forms.

UK Patent Application No.8829571 is European patent application EP 0 375 329 and U.S. Patent application No.5,043,339 require priority patent, wherein disclosed amino acid ester and its physiologically acceptable salt of the compound of representing with following formula,

(wherein R representation hydroxy or amino or hydrogen atom).The preferred amino acids example is the aliphatic amino acid that contains six carbon atom at most, as: glycine, L-Ala, Xie Ansuan and Isoleucine.Amino acid ester comprises monoesters and dibasic acid esters.The preparation method of dibasic acid esters is identical with European patent application EP 0 375 329, yet this patent application also has European patent application EP 0 375 329 and US Patent No: 5,043,339 all do not disclose the preparation method of monoesters and the data of their application facet.

Leon Colla etc. have disclosed several soluble ester analog derivatives of acyclovir and its salt as the acyclovir prodrug in pharmaceutical chemistry magazine (J.Med.Chem.) (1983) 26,602-604.The author points out that acyclovir can not do eye drops and intramuscular injectable formulations, because it is limited water-soluble, has therefore synthesized the derivative of the water-soluble acyclovir higher than parent compound.The author has disclosed glycyl ester hydrochloride, alanyl ester hydrochloride, b-alanyl ester hydrochloride, succinyl-ester sodium salt and nitrine acetic ester.The alanyl ester can prepare by conventional esterification process; be included in 1; the tosic acid of 3-dicyclohexyl carbodiimide and catalytic amount exists down; in pyridine; with the reaction of the amino acid of acyclovir and corresponding N-carboxy protective, and then carry out catalytic hydrogenation and obtain α-and β-alanyl ester hydrochloride.

L.M.Beauchamp etc., in antiviral chemistry and chemotherapy (1992), 3 (3), disclosed the aminoacyl ester class antihepatitis drug of 18 acyclovirs and they effect in the 157-164 document, and in rat urine, reclaimed and assess by measuring acyclovir as the acyclovir prodrug.Ten kinds of yields in urine are the glycyl esters of acyclovir greater than the compound of acyclovir itself, D, L-alanyl ester, L-alanyl ester, L-2-aminobutyric acid ester, D, L-L-valine ester, L-valyl ester, DL-isoleucyl-ester, L-isoleucyl-ester, L-methinyl ester and L-prolyl ester.The L-valyl ester of acyclovir is best prodrug in the ester class that the author points out to be studied.The preparation method of these esters is similar to that Colla etc. adopted.

European patent discloses 308 065 and has disclosed the L-valine ester of acyclovir and Isoleucine ester and preferred L-configuration, because its intestinal absorption amount increases much than acyclovir itself and other ester when oral.These amino acid esters can prepare by conventional esterifying reaction method; be included in as in the kind solvents such as pyridine or dimethyl formamide; optionally in the presence of catalysis alkali, the amino acid of acyclovir and N-carboxy protective or carboxylic acid halides or amino acid whose acid anhydrides are reacted and prepare.The amino acid ester of acyclovir also can prepare the reaction that guanine and amino acid side chain intermediate carry out condensation by the similarity method that discloses with English Patent GB 2 122 618.

PCT patent application WO 94/29311 has disclosed the preparation method of the amino acid ester of the nucleosides homologue that comprises acyclovir and ganciclovir.But this method comprises having the 2-oxa--4-azepine-cycloalkyl-1 of the nucleoside analog and the following formula of esterified hydroxy groups on linearity or cyclic ether part, the 3-diketone reacts, the acyclovir that obtains expecting or the glycinate of ganciclovir, alanine ester, L-valine ester, the Isoleucine ester.

R wherein ¹Represent hydrogen atom, C _1-4Alkyl or alkenyl or other amino acid side chain, R ²Represent hydrogen atom or COOR ³, R wherein ³Be benzyl, tert-butyl, the C of the straight or branched that fluorenyl methyl or selectivity halogen replace _1-8Alkyl.R ¹Be preferably hydrogen atom, methyl, sec.-propyl and isobutyl-.PCT patent application WO 94/29311 embodiment 1-3 has only disclosed the 2-oxa--4-azepine-cycloalkyl-1 of acyclovir and Xie Ansuan replacement, the condensation reaction that 3-diketone (Z-valyl-N-carboxyl-acid anhydrides) carries out with common method.When the amino acid ester of this PCT application comprised acyclovir and ganciclovir, this application did not disclose the preparation method of ganciclovir ester, does not more disclose the preparation method of ganciclovir monoesters.

European patent application No.694.547 has disclosed the methoxyl group-1 from 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl), and the single valyl ester of ammediol and its drug salts deutero-L-is strong antiviral agent.These toxicity of compound are low, and oral absorption is good.This patent application has also disclosed the preparation method of these esters, and method and method described herein are different.

The present invention relates to the new intermediate that the acid salt of ganciclovir of an improved preparation method and monohydroxy protection is represented; compare with known intermediate; this method has reduced the impurity in the end product list valyl ester; thereby the time and the expense of purification step have been cut down; and the initiator of permission use low-purity, this makes the cost of product descend conversely.

First aspect present invention provides the preparation method of formula I compound and its pharmaceutical salts,

This compound is called after 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl) methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester or ganciclovir list L-L-valine ester from now on.

This method comprises that the guanine of selectivity replacement and the glycerol derivative of replacement carry out condensation reaction, form the formation of the acid salt of the ganciclovir of protecting as the monohydroxy of intermediate subsequently; This product and L-valine derivative are carried out esterification slough protecting group then, thereby obtain the prodrug of formula I.In addition, this method also optionally comprises the salt that forms formula I prodrug, formula I prodrug acid salt is transformed into the crystallized form of salt-independent shape, optical resolution formula I prodrug or preparation formula I prodrug then.This method is described in detail as follows.

Second aspect present invention provides the formula V and the formula VI compound of the useful intermediates of single L-Xie Ansuan of being used to prepare ganciclovir and its pharmaceutical salts.Formula V compound is:

Wherein X represents acid salt part, Y ²Represent halogen, the aralkoxy that low-grade acyloxy or selectivity replace, P ¹Represent hydrogen atom or an amido protecting group.Formula IV compound is:

P wherein ¹Represent the amido protecting group, it is C _1-4Lower acyl, Y ¹Represent halogen, the aralkoxy that low-grade acyloxy or selectivity replace, Y ²Represent C _1-4Low-grade acyloxy.

Third aspect present invention relates to preparation formula V and the new intermediates preparation of IV.

Definition:

Except as otherwise noted, following term is all represented the following meaning in declaratives and claims:

" BOC " represents uncle-butoxy carbonyl,

" CBZ " represents carbonyl benzyloxy (benzyloxycarbonyl),

" FMOC " represents N-(9-fluorenyl methoxy carbonyl),

" DHPG " represents 9-[(1,3-dihydroxyl-2-propoxy-) methyl] guanine,

" alkyl " expression contains one to the saturated alkyl of specifying carbonatoms purpose straight or branched, for example, and C _1-7Alkyl represents to contain at least one but the alkyl of no more than seven carbon atoms, as: methyl, ethyl, sec.-propyl, n-propyl, normal-butyl, n-pentyl, n-heptyl etc.,

One one alkyl of " low alkyl group " expression to six carbon atom,

The aromatic group of a hydrogen atom is removed in " aryl " expression, and preferred aryl groups is the ring (as: naphthyl) of monocyclic carbocyclic aryl ring (as: phenyl) or two condensations,

Hydrogen atom is replaced by the aryl of above-mentioned definition in " aralkyl " expression alkyl

Remove the group of hydroxyl in " acyl group " expression organic acid, as: CH ₃CO-or ethanoyl are CH ₃The acyl group of COOH, other example has propionyl, benzoyl etc.Term " aryl " also comprises term " alkanoyl ", and it is the RCO-group, and wherein R represents alkyl as defined above,

" lower alkoxy ", " low-grade alkyl amino ", " two (low alkyl group) amino ", " (lower alkane acyl group) amino " and similar terms are represented alkoxyl group, alkylamino, dialkylamino, alkyl amido etc., wherein each alkyl is all represented " low alkyl group ",

" halogen " or " halogen " expression fluorine, chlorine, bromine or iodine,

" trityl " expression trityl (PH) ₃C-,

The compound that " derivative " expression obtains from former compound by simple chemical process.

The activated form of the former compound of " activated derivatives " expression, it represents that this compound is an activatory at required chemical reaction, and former compound only has moderate activity or non-activity.Activation is to realize than derivative or chemical group that former compound has higher free energy by formation in molecule, thereby provide with other reagent the more activated form of hyperergy is arranged, in the content of the present invention, the activation particularly important of carboxyl, details are as follows for the group of corresponding activator or activated carboxyl.An example of the activated derivatives of L-Xie Ansuan is a formula VI compound:

P wherein ²Be the amido protecting group, A is the activating group of carboxyl, for example, halogen, low-grade acyloxy, carbodiimide groups is as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC), isobutyrate etc.

Significant especially amino acid whose activated form is amino acid anhydrides among the present invention, and it makes amino acid (particularly L-Xie Ansuan) to the esterification sensitivity.Amino acid anhydrides is included in the formula VI compound.Useful especially among the present invention is in the cyclic amino acid anhydrides of the L-Xie Ansuan described in the PCT patent application WO 94/29311, as: the 2-oxa-that formula VI a represents-4-azepine-5-sec.-propyl-cyclic alkyl-1, the 3-diketone,

Wherein P2 is the amido protecting group.The example of another cyclic amino acid anhydrides is the amino acid N-carboxylic acid (NCAs) of the following protection of more describing in detail.

The such chemical group of " protecting group " expression: (a) prevent that reaction active groups from participating in the chemical reaction of not expecting; (b) when no longer needing protection active group, can remove easily.For example, benzyl is the function and protecting base of primary hydroxyl.

" amino protecting group " expression can be protected the blocking group of activated amino, otherwise amino meeting is by the chemical reaction modification of some.This protecting group comprises formyl radical, the low-grade alkane acidyl of 2-4 carbon, especially ethanoyl or propionyl; the trityl of trityl or replacement, as: mono methoxy trityl, dimethoxytrityl; as 4,4 '-dimethoxytrityl, phenyl-diformyl base; silyl, tribromo-acetyl base, trifluoroacetyl group; N-(9-fluorenyl methoxy carbonyl) or " FMOC " base; allyloxy carbonyl, or other is by halo carbonic ether deutero-blocking group, as: carbonic acid (C ₆-C ₁₂) aromatic yl elementary alkyl ester (as: by chlorine carbonic acid benzyl ester deutero-N-benzyloxycarbonyl); or by the blocking group of diphenyl alkyl halocarbon acid esters or tertiary alkyl halocarbon acid ester derivative; as: tertiary butyl halocarbon acid esters; uncle's fourth halocarbon acid esters particularly; or two (rudimentary) alkyl, two carbonic ethers, preferred two (tertiary butyls), two carbonic ethers, and trityl group halides; as: trityl group chlorine, and trifluoroacetic anhydride.

" hydroxyl protecting group " expression prevents that hydroxyl is by some chemical reaction destructive blocking groups.In the present invention; hydroxyl protecting group can be that ether or ester form group, and after all other reactions steps were finished, these ethers or ester can be easy to be removed; as lower acyl (as: acetyl or propionyl), or aralkyl (as: benzyl that the replacement selected is arranged on phenyl ring).

" silylation catalyzer " is meant the catalyzer that can promote the guanine silylation, for example: the sulphonyl ammonium, tosic acid, trifluoromethanesulfonic acid, trimethyl silyl fluoroform sulphonate, two trimethyl silyl sulfonate, sulfuric acid, butyl sulfonic acid potassium, ammoniumper chlorate, sodium perchlorate, Sodium tetrafluoroborate or tin tetrachloride.

" silylating agent " is meant the compound that can make the guanine silylation.Preferred silylation reagent is that (it is formula II a compound, wherein R to hexamethyldisilazane ⁵, R ⁶And R ⁷Be methyl).Yet many other silylation reagent are known in the art, for example, and can be with guanine and formula SiR ⁵R ⁶R ⁷The trialkylsilkl halogen reaction of X, wherein R ⁵, R ⁶And R ⁷Be respectively low alkyl group, X is a chlorine or bromine, as: trimethylsilyl chloride, tert-butyldimethylsilyl chloride etc. preferably react in the presence of 1-2 molar equivalent alkali.The high silylation reagent that formula II a represents is as follows:

This formula is represented by the guanine of one, two or three silyl protection, or its mixture, wherein Z ¹, Z ²And Z ³Represent hydrogen atom or formula SiR respectively ⁵R ⁶R ⁷Silyl, condition is Z ¹, Z ²And Z ³In have at least one to be silyl, R wherein ⁵, R ⁶And R ⁷Represent low alkyl group respectively.It should be noted that formula II a represents N-7 and N-9 mixture of isomers (also being the mixture of tautomer).

" leavings group " is illustrated in can be by the easy leavings group of other group displacement in the chemical reaction.For example, halogen, benzyloxy, mesyloxy, tosyloxy or acyloxy that selectivity replaces.

In the preparation process of formula I compound, all activators and protective material must meet following standard: (1) must quantitatively add, and does not cause the racemization of L-Xie Ansuan; (2) in the reaction that will carry out, blocking group should be stable to reaction conditions; (3) this group is easy to remove and reaction conditions should be not destroy ester bond, and does not cause the L-Xie Ansuan composition racemization of ester.

The present invention also comprises the optical resolution with formula I prodrug.About terms such as the stereochemistry of these compounds and optical resolution were described in european patent application No.694.547, for reference in this insertion.

" selection " or " optionally " refers to that described thing or environment can exist, and also can not exist, and for example: " phenyl that selectivity replaces " expression can be substituted or not substituted phenyl, promptly comprises non-substituted-phenyl and substituted-phenyl; This transformation that the expression that " optionally changes free alkali into acid salt subsequently " belongs to method of the present invention can be carried out, and also can not carry out, and wherein free alkali can also can convert the additive salt of acid to.

" medicinal " expression can be used for pharmaceutical compositions, and it generally is that safe and nontoxic comprising can be used for veterinary drug or people's medication.

" pharmaceutical salts " represents that this class salt has the pharmacologically active of expectation, and other biological activity that does not expect to have.Such salt comprises the acid salt example hydrochloric acid that forms with mineral acid, Hydrogen bromide, sulfuric acid, nitric acid, phosphoric acid etc.; Or the acid salt such as the acetate that form with organic acid, propionic acid, caproic acid, enanthic acid; the pentamethylene propionic acid, oxyacetic acid, pyruvic acid, lactic acid; propanedioic acid, succsinic acid, oxysuccinic acid, toxilic acid; fumaric acid, tartrate, citric acid, phenylformic acid; o-(4-hydroxyl-benzoyl)-phenylformic acid, styracin, amygdalic acid, methylsulfonic acid; ethyl sulfonic acid, 1,2-ethane-disulfonic acid, 2-hydroxyl ethane-sulfonic acid; Phenylsulfonic acid, right-chlorobenzenesulfonic acid, the 2-naphthene sulfonic acid, right-toluenesulphonic acids; camphorsulfonic acid, 4-methyl-two ring [2,2,2] oct-2-ene base-1-formic acid; glucose-enanthic acid, 4,4 '-methylene-bis (3-hydroxyl-2-naphthalene first) acid, 3-phenylpropionic acid; trimethylammonium-acetate, tert.-butylacetic acid, lauryl sulfate; gluconic acid, L-glutamic acid, hydroxynaphthoic acid; Whitfield's ointment, stearic acid, glactaric acid etc.Preferred pharmaceutical salts is the salt that forms with following acid: hydrochloric acid, and sulfuric acid, phosphoric acid, acetate, methylsulfonic acid, ethyl sulfonic acid, 1, the 2-ethane disulfonic acid, the 2-ethylenehydrinsulfonic acid, Phenylsulfonic acid, right-chlorobenzenesulfonic acid, 2-naphthene sulfonic acid, right-toluenesulphonic acids and camphorsulfonic acid.

The building-up reactions parameter

Unless otherwise indicated, (preferably in 10 ℃ to 50 ℃ scopes, more preferably in " room temperature " or " envrionment temperature ", as 20-30 ℃) are all carried out in reaction as described herein in normal atmosphere and 5 ℃ to 170 ℃ temperature ranges.Yet, clearly the temperature of some reaction can on these temperature or under.Have, unless otherwise noted, the time of reaction and condition also are roughly again.For example, in normal atmosphere and 5 ℃ to 100 ℃ temperature ranges, react (preferably in 10 ℃ to 50 ℃ scopes), reaction times 1-100 hour (preferred 5-60 hour) more preferably at 20 ℃.The parameter that provides among the embodiment is concrete, is not roughly.

Compound as described herein and intermediate separate and the method for purifying is effective, as needs, any suitable separation and purification step, as: filter, extract crystallization, column chromatography, thin-layer chromatography, the combination of slab chromatography or these methods all can be used, the suitable separation and the specifying referring to following embodiment of purification step.Yet other suitable isolated or purified step also can be used.

The definition of maximum range of the present invention is summarized in formula I compound and its pharmaceutical salts (among the preparation method of preferred (R, S) mixture and its some salt).

Preferred following acid and formula I compound can form drug salts: hydrochloric acid, and sulfuric acid, phosphoric acid, acetate, methylsulfonic acid, ethyl sulfonic acid, 1,2-diethyl sulfonic acid, 2-hydroxyethyl sulfonic acid, Phenylsulfonic acid, right-chlorobenzenesulfonic acid, 2-naphthene sulfonic acid, right-toluenesulphonic acids and camphorsulfonic acid.Strong inorganic acid most preferably, example hydrochloric acid, sulfuric acid, or phosphoric acid.

Most preferred compound is 2-(2-amino-1,6-dihydro-6-oxo-purine-9 base) methoxyl group-3 hydroxyls-1-propyl group L-L-valine ester hydrochloride and acetate.These compounds can be prepared to crystallization, and therefore are easy to make stable oral preparation.

In any one final reaction step of Miao Shuing, contrast the formula I, II, III, IV, V, VI, VI a or VII, wherein P here ¹And P ², A, Y ¹, Y ², the wideest definition in Z and X such as the present invention's general introduction, the method for employing is represented preferred embodiment.

The inventive method is as described in the following reaction scheme:

P wherein ¹Be hydrogen atom or amido protecting group, P ²Be the amido protecting group, X is the medicinal acid addition salt group.Formula III compound is a glycerol derivative, wherein Y ¹And Y ²Represent halogen respectively, low-grade acyloxy, or the aralkoxy of selectivity replacement, or Y ¹And Y ²One of be valyl oxygen base, Z is for being selected from low-grade acyloxy, isopropoxy, benzyloxy, halogen, the leavings group of mesyloxy or tosyloxy etc.Y in the common glycerol derivative ¹And Y ²Need to select, to obtain single L-L-valine ester of formula I, i.e. Y by such method ¹And Y ²One of the L-valyl oxygen base of amido protecting, maybe can be transformed into the group of L-valyl oxygen base.

Optionally the formula II guanine compound of high silylation and formula III 2-substituted glycerol carry out condensation reaction; obtain formula IV 2-(2-amino-1; 6-dihydro-6-oxo-purine-9-yl) methoxyl group-1, ammediol (ganciclovir) intermediate, wherein two hydroxyl functional bases are protected (or works as Y ¹And Y ²In only need when having one to be valyl oxygen base a hydroxyl functional base protected), the amino part of the 2-of guanine is protected by selectivity.When two hydroxyl functional bases were all protected, the protection that formula IV compound is sloughed a hydroxyl obtained the ganciclovir intermediate of single protection, subsequently or carry out the preparation of acid salt simultaneously, obtained the new intermediate of formula V.Formula V compound obtains formula VII compound with the activated derivatives esterification of formula VI or V ia L-Xie Ansuan, next optionally removes amino and/or hydroxyl protecting group and obtains formula I compound.

If in the step I, introduce L-valyl oxygen base, wherein Y with glycerol derivative ¹And Y ²In have one to be the group that the L-valyl oxygen base of amido protecting maybe can be transformed into L-valyl oxygen base, and another is hydroxyl protecting group, then product formula IV compound can directly be changed accepted way of doing sth I compound by removing hydroxyl and amido protecting group.

Formula I compound optionally is transformed into drug salts.This method also can comprise and formula I prodrug acid salt is transformed into salt-independent shape, the preparation of the optical resolution of formula I compound and formula I compound crystal.

The present invention is the improvement preparation method of single L-Xie Ansuan ganciclovir, and the formation of its Chinese style V intermediate has unprecedented unique advantages.This novel intermediate is the acid salt of the ganciclovir of monohydroxy protection, and it provides significantly reducing of several impurity relevant with end product.

At first, being used to prepare the initiator of some formula III glycerine reagent can be by some contaminating impurity.These impurity are not removed when synthetic glycerine reagent, when this glycerine reagent and guanine carry out condensation reaction, can produce the impurity isomer of corresponding ganciclovir.For example, the starting raw material of formula III glycerine reagent, wherein Y ¹Be benzyloxy, Y ²With Z be propionyloxy, can be 1-benzyloxy-3-chloro-2-propyl alcohol.This initiator can contain 2-chloro-3-benzyloxy propyl alcohol or 2-benzyloxy-3-propylene chlorohydrin.These impurity will provide corresponding impure glycerine reagent.In the condensation reaction of ensuing and guanine generation, impurity will bring the isomer impurities of ganciclovir intermediate.

Secondly, the reaction of guanine and formula III glycerine reagent produces the product mixture of isomers: desired 9-9 substituted guanine (9-isomer) and a spot of 7-9 substituted guanine of not expecting (7-isomer).If glycerine reagent contains above-mentioned impurity, then the impurity isomer of corresponding ganciclovir also will exist.These impurity can not be removed from the 9-isomer at an easy rate.

The invention provides the preparation method of the acid salt of formula V compound, it isolates the end product that does not have the 7-isomer substantially, and it makes impurity reduce 50% at least.This acid salt intermediate can directly prepare with the guanine reaction mixture of the formula IV compound that contains the dihydroxyl protection.Perhaps, formula IV compound can at first go the protection of a hydroxyl and obtain the ganciclovir that monohydroxy is protected, then by this intermediate preparation acid salt.Also have, it at first is prepared into two hydroxyl protections and the intermediate of the guanine 2-amino protected with the acyl group acid anhydrides by formula IV compound.This step has very strong superiority, because the full guard intermediate can crystallization, and the 7-isomer of expectation invariably.By this full guard intermediate, the separable ganciclovir that goes out as the new monohydroxy protection of acid salt separates.The compound of full guard is new intermediate, and is the compound that the general formula IV is represented, wherein P ¹Representative has the lower acyl class amido protecting group of 1-4 carbon atom, Y ¹Represent halogen, the aralkoxy that low-grade acyloxy or selectivity replace, Y ²Representative contains the low-grade acyloxy of 1-4 carbon atom, P like this ¹And Y ²Acyloxy be the same.Preferred full guard intermediate is two propionyls-monobenzyl-ganciclovir or diacetyl-monobenzyl-ganciclovir.

In general, the preparation method of formula I compound can comprise also can not comprise protection amino on the guanine alkali 2-position, and these protecting groups can or be removed after esterif iotacation step before forming formula V intermediate salt, remove in the time of also can in the end going to protect step.Concerning the ganciclovir intermediate that 2-amido protecting group is arranged, protecting group can be removed by ordinary method.For example:, can remove protecting group by alkaline condition (pH is in the 8-11 scope) if the amido protecting group is a low-grade alkane acidyl.For example: 2-N-ethanoyl-ganciclovir intermediate is handled with alkali (as: ammonium hydroxide, yellow soda ash or potassium, or sodium hydroxide or potassium) and is removed fully up to ethanoyl.In general, this reaction will be carried out in The suitable solvent, as: low-grade alkane alcohol.Preferably initiator is dissolved in the methyl alcohol, adds the excessive ammonium hydroxide of stoichiometry, temperature of reaction remains on 0 ℃-50 ℃, preferred room temperature.(can detect by TLC) added the separation that another solvent promotes to go to protect product after reaction was finished, as: ether, it causes the product precipitation of deacetylate, thereby filters and separation by ordinary method.

In general, when carrying out the inventive method, those do not participate in the amino of building-up reactions; hydroxyl; or carboxyl must be protected, remove this protection up to (1) and just can obtain end product, (2) in causing the reactions steps of end product not the existence of blocking group do not change reaction sequence.The example of (1) of meeting the demands is the carbobenzoxy-(Cbz) in the preparation of end product in the present invention, and the amino on the Xie Ansuan of its protection ganciclovir is up to being removed in deprotection steps.The embodiment of (2) of meeting the demands is amino on the guanine ring of protection ganciclovir, and ethanoyl, or trityl, or mono methoxy trityl be not because unprotected amino influences esterification (step III).

In general, the condition that is applicable to the strong blocking-up reagent in the formula I compound comprises:

(1) they quantitatively are incorporated in the reaction reposefully, and do not cause the racemization of L-Xie Ansuan;

(2) the blocking-up intermediate must be stable up to requiring to remove protecting group to reaction conditions;

(3) blocking group must be responsive to the reaction conditions of removing it, and this condition can not cause that the chemical property of molecule other parts changes and the racemization of L-Xie Ansuan composition.

The silylation of guanine

Z wherein ¹, Z ²And Z ³Be respectively hydrogen atom or formula R ⁵R ⁶R ⁷The silyl protecting group of Si, wherein R ⁵' R ⁶And R ⁷Represent low alkyl group respectively, condition is Z ¹, Z ²And Z ³Among have at least one to be silyl.

The preparation of formula II a silylanizing guanine

Formula R ⁵R ⁶R ⁷The trialkylsilkl halogen or the hexamethyldisilazane of Si (wherein X represents chlorine or bromine) expression can commercially availablely obtain.

Illustrating in above-mentioned reaction scheme, the guanine of silylation produces corresponding formula II a silylation compound.

The protection of guanine is known (for example, referring to " the synthetic A Review of 9-9 substituted guanine " by F.P.Clausen and J.J.Christensen, Org.Prep.Proced.Int., 25 (4), pp 375-401 (1993)) in this area.For example: guanine can be used acyl group (as: ethanoyl), or silyl is protected.Traditionally, when silyl was used to protect, guanine is silylanizing by this way, and promptly before required reaction was carried out, all activated protons on the guanine were all replaced by silyl, and guanine is protected to be the front three silane derivative.Yet, carry out the expected product that step (a) condensation reaction obtains high yield subsequently although have been found that guanine three silylanizings, this point is very important, but guanine three silylanizings are dispensable for condensation in the step (a), and the condensation reaction of step (a) is a particularly important to the preparation of compound (IV).Usually, the soup compound of guanine and silylation reagent (as: hexamethyldisilazane) reflux and react down, become solution until suspended substance, and the formation of this signal indication front three silane derivative finishes.This reaction needed 48 hours or longer time.Have been found that return time time still less, as 2 hours, then with the soup compound that obtains as described in the step (a) with the reaction of formula III compound, can obtain the expected product of high yield.Clearly this result has very high superiority, because shorten the reaction times, the consumption that reduces silylation reagent can reduce cost.Although (the II a) composition of product is also not fully aware of for the formula that the hexamethyldisilazane that carry out within a short period of time and the reaction of guanine generate, but can believe that they mainly are single silylanizing derivatives, perhaps be mixed with some dimethyl silanylizations and three silylanizing guanines.

In a preferred method, the silylation reagent react of guanine and about 3-10 molar equivalent preferably (promptly provides formula II a compound, wherein R with hexamethyldisilazane ⁵, R ⁶And R ⁷Represent methylidenes all) reaction is having in the presence of the silylation catalyzer, preferably sulfuric acid ammonium, trifluoromethanesulfonic acid, trimethyl silyl-fluoroform sulphonate and two trimethyl silyl sulfonate, preferred trifluoromethanesulfonic acid (about 0.01-0.1 molar equivalent).Mixture is heated backflow 5-24 hour, preferred 16 hours.After reacting completely, excessive silylation reagent is depressurized to be removed, formula (protection that II a) is represented guanine product solution can directly enter next reactions steps, and do not need to be further purified.

Perhaps, as above as described in the paragraph, guanine and the preferred hexamethyldisilazane of silylation reagent, reaction in the presence of the preferred trifluoromethanesulfonic acid of silylanizing catalyzer, but the reaction times be 1-8 hour, preferred 2-4 hour.

The removal of optionally reducing pressure of excessive silylation reagent, (product mixtures that the guanine a) represented of II is protected can directly enter next reactions steps to formula, and does not need to be further purified.

Perhaps, guanine can with the formula SiR of 1-5 molar equivalent ⁵R ⁶R ⁷X (R wherein ⁵, R ⁶And R ⁷Represent low alkyl group respectively, X represents chlorine or bromine) the trialkylsilkl halogen of expression, in the presence of the alkali of 1-5 molar equivalent, react, as: trimethyl silyl oxygen, tertiary butyl dimethylsilane chlorine etc.

It should be noted ammonium sulfate, trifluoromethanesulfonic acid, the trimethyl silyl fluoroform sulphonate, or two trimethyl silyl sulfonate is good silylation catalyzer in above-mentioned guanine silylation.But preferred trifluoromethanesulfonic acid is because it is more cheap than trimethyl silyl trifluoromethyl sulfonic acid or two TMS sulfonate.

Initiator

All initiators that is used for preparation all are known, as: guanine, protective material and carboxyl activator.

Carry out the formula III glycerol derivative of condensation reaction sees among the open No.694.541 and 187 297 of pending European application with guanine or the guanine protected.European patent application 187 297 has also been described the preparation method of formula III glycerol derivative.The preferred method of preparation glycerol derivative will be described in " preparation of glycerol derivative " chapters and sections below.

Preferred guanine initiator is unprotected guanine; preferred glycerol derivative is 1-propionyloxy-2-propionyloxy methoxyl group-3-benzyloxy propane; 1-acetoxyl group-2-acetoxyl group methoxyl group-3-benzyloxy propane, or 1-benzyloxy-2-acetoxyl group methoxyl group-3-benzyloxy propane.

Carrying out step II (step of esterification) before, the amino on the L valine derivative must be protected, forms unwanted amide compound to avoid amino interference esterification.The L-valine derivative of the various amido protectings of using among the present invention such as N-benzyloxycarbonyl-L-Xie Ansuan; BOC-L-Xie Ansuan and FMOC-L-Xie Ansuan; N-formyl radical-L-Xie Ansuan and N-benzyloxycarbonyl-N-carboxyl-L-Xie Ansuan acid anhydride all has supply of commodities (SNPE Inc.; Princeton; NJ; aldrichChemical Co.; Milwaukee, WI and Sigma Chemical Co.; St; Louis MO.), or has description in the literature; as N-allyloxy carbonyl-L-Xie Ansuan, the L-valine derivative of cyclic amino protection carbonyl was also described in above-mentioned document.2-oxa--4-azepine-cycloalkyl-1 that special for purposes of the invention carbobenzoxy-(Cbz) Xie Ansuan meaningfully replaces, the 3-diketone (Z-Xie Ansuan-N-carboxylic acid anhydride, or Z-Xie Ansuan-NCA), they also have supply of commodities (SNPE Inc., Princeton, NJ).In addition, the also available ordinary method of protection step is carried out.

The preparation method of formula III glycerol derivative

Being used for glycerol derivative of the present invention can prepare from known initiator.For example, formula III compound (Y wherein ¹Represent rudimentary aralkoxy or halogen, Y ²Be low-grade acyloxy or halogen, Z represents low-grade acyloxy) can be prepared as follows.This reaction can be used as and prepares wherein Y ¹Represent benzyloxy, Y ²Represent propionyloxy, Z represents the compound of propionyloxy, i.e. the illustration of 1-benzyloxy-3-propionyloxy-2-(propionyloxy) methoxy propane.

In the presence of the hydrogen sulfate TBuA, in aqueous sodium hydroxide solution,, Epicholorohydrin and benzylalcohol are reacted in room temperature.Reaction product benzyl glycidyl ether can separate with general method, and is preferred below 60 ℃ in 40 ℃ of-70 ℃ of scopes under the condition of tetrahydrofuran (THF) and acetate existence afterwards, slowly it added in the suspension of lithium chloride.Reaction mixture stirred 2-10 hour to room temperature, preferred 3-6 hour.With the method separated product that extracts, washing, drying obtains 1-benzyloxy-3-chloro-2-propyl alcohol.Then this product is added in the propionic acid methoxymethyl ester that (the propionic acid methoxymethyl ester can be under the condition that ion exchange resin such as Amberlyst 15 exist, propionic anhydride is added in the Methylal(dimethoxymethane) and prepares, for example, temperature remains in 40 ℃ of-60 ℃ of scopes during the interpolation, preferred 40 ℃-50 ℃).Reaction mixture is placed and cools off, and filters washing, distillation then.Product propionic acid methoxymethyl ester (as: hexane) in sprotic solvent reacts under refluxing with 1-benzyloxy-3-chloro-2-propyl alcohol in the presence of the tosic acid hydrate.Distillation, washing obtains product 1-benzyloxy-3-chloro-2-(propionyloxy)-methoxy propane.At last, for preparation formula III compound, in sprotic solvent (as: toluene), after adding tetrabutyl phosphoryl chloride, 1-benzyloxy-3-chloro-2-(propionyloxy)-methoxy propane is refluxed with Sodium Propionate.Reaction mixture stirred 1-3 days down for 90 ℃ at reflux temperature, preferred two days, during this period of time, constantly replenish tetrabutyl phosphoryl chloride and solvent.Mixture is heated to backflow, remove distillment then, at 90 ℃ of restir 3-16 of reflux temperature hours, preferred 5-10 hour, be cooled to envrionment temperature then, water and salt water washing separate organic phase, concentrate, obtain 1-benzyloxy-3-propionyloxy-2-(propionyloxy)-methoxy propane.But other glycerol derivative with similar approach also preparation formula III.

The preparation method of L-Xie Ansuan activatory derivative

Carrying out step II (step of esterification) before, the L-Xie Ansuan also must be activated.At least 1 normal protected amino acid and 1 normal suitable coupling agent or dewatering agent (for example, 1, the 3-dicyclohexyl carbodiimide or have the salt of this imines of base) be used to initial action.Other carbodiimide, as: N, N '-carbonyl dimidazoles also can use.Available dehydrated reagent comprises trifluoroacetic anhydride, mixed acid anhydride, acyl chlorides, 1-benzo-triazole oxygen base-three (hexafluorophosphate of dimethylamino) Phosphonium, the hexafluorophosphate of benzotriazole-1-base-oxygen base-tripyrrole alkane Ji Phosphonium, I-hydroxybenzotriazole, 1-benzo-4-azepine benzotriazole, 1-hydroxyl-7-azepine benzotriazole, N-ethyl-N '-(3-(dimethylamino)-propyl group) carbodiimide hydrochloride, 3-hydroxyl-3,4-dihydro-4-oxo-1,2, the 3-phentriazine, o-(benzo-triazol-1-yl)-1,1,3, the hexafluorophosphate of 3-tetramethyl-urea, o-(7-azepine benzo triazol-1-yl)-1,1,3, the hexafluorophosphate of 3-tetramethyl-uric acid, o-(7-azepine benzo triazol-1-yl)-1,1,3, the a tetrafluoro borate of 3-tetramethyl-urea, o-(1H-benzotriazole-1-yl)-1,1,3, the hexafluorophosphate of two (tetramethylene) ureas of 3-, or o-(7-azepine benzo triazol-1-yl)-1,1,3, the hexafluorophosphate of two (tetramethylene) ureas of 3-.The visible JACS 1993,115 of coupling reagent that these are described by L.A.Carpino, P.4397-4398.

Be used for this purpose and still be the amino acid, n-carboxyanhydrides (UNA ' S) of urethane protection, it is amino acid whose activated form.People such as this visible William D.Fuller, JACS 1990,112,7414-7416, it inserts as a reference at this.The amino acid, n-carboxyanhydrides of other protection is seen above-mentioned PCT patent application WO94/29311.In a word, under mild conditions, any energy produces the amino acid whose acid anhydrides of protection or the reagent of another reactive derivative all can be used as coupling agent.

The amino acid of amido protecting is dissolved in the inert solvent (as: lower paraffin hydrocarbons that halogen replaces in rare gas element (as: nitrogen); preferred methylene dichloride) in; add coupling agent (preferred 1; the 3-dicyclohexyl carbodiimide); at 0-50 ℃ of (preferred room temperature) stirred reaction mixture; filter, separate obtaining product (the amino acid anhydrides of protection).Product is dissolved in the anhydrous inert solvent (as: anhydrous methylene chloride), places under the nitrogen atmosphere.

The preparation of list-L-Xie Ansuan ganciclovir

The step I:

The guanine of the 2-amino of selective protection carries out the condition of condensation reaction to be described in european patent application 187 297; under such condensation reaction condition; guanine and formula III glycerol derivative are at sprotic hydrocarbon solvent (as: benzene; toluene; or dimethylbenzene) reaction in; or at dimethyl formamide and six-low alkyl group (two) silazane (as: hexamethyldisilazane; hexaethyl disilazine etc.) there is reaction down; temperature of reaction 30 ℃ between the reflux temperature, also have catalyzer to exist.Catalyzer is the salt (as: trialkylsilkl salt such as vitriol) of Lewis acid, or trifluoroalkyl sulfonic acid, silicon chlorides azane, or ammonium sulfate and pyridine.The more detailed situation of condensation step I reaction conditions is seen european patent application 187 297, and it inserts as a reference at this, and product is the ganciclovir derivative that has the 2-amino of the hydroxyl of protection and selective protection.

For example, formula IV ganciclovir intermediate, wherein Y ¹Represent low-grade acyloxy, Y ²Represent benzyloxy, guanine that can be by high silylation and formula III glycerol derivative (Y wherein ¹Represent low-grade acyloxy with Z, Y ²Represent benzyloxy) carry out condensation reaction and prepare.Representative instance is, under the condition that the Lewis of catalytic amount acid (preferred trifluoromethanesulfonic acid) exists, in 60-150 ℃ of (preferred 110-130 ℃) temperature range, high silanization guanine and excessive greatly formula III glycerol derivative reaction 3-24 hour (preferred 6-8 hour), cooling, with proton inertia and nonpolar solvent (preferred toluene) dilution, carefully add entry then, product can be with filtering method selective separation.

The step II:

The ganciclovir derivative that is protected from the step I is partly gone protection, obtains having selective protection 2-amino, the ganciclovir of the primary hydroxyl functional group of a protection, and preferably this hydroxyl is by benzyl protection.Suitable amino protecting group is the low-grade alkane acidyl (as: ethanoyl or propionyl) with 2-4 carbon atom; other suitable amino protecting group also has the trityl (as: mono methoxy trityl and 4,4 '-dimethoxytrityl) of trityl or replacement.

As mentioned above, the acid salt of formula V compound can directly prepare from step I product, and the compound that the dihydroxyl that step I product is represented for the formula IV is protected goes the preparation of a hydroxyl protection and salt to carry out simultaneously.Perhaps, formula IV compound can at first be sloughed the protection of a hydroxyl, obtains the ganciclovir of a monohydroxy protection, then by its preparation acid salt.Also can (for example: acid anhydrides) at first prepare intermediate that two hydroxyls and guanine 2-amino all protects by formula IV compound.The acid salt (formula V) that can prepare the ganciclovir of new monohydroxy protection from this intermediate.For example, in toluene, propionyl monobenzyl ganciclovir intermediate and propionyl acid anhydride/dimethyl aminopyridine reaction that the formula IV is represented can prepare two propionyl monobenzyl ganciclovir intermediates.As mentioned above, the ganciclovir intermediate of two hydroxyl protections and guanine 2-amido protecting (as: two propionyl monobenzyl ganciclovirs) is preferred intermediate, does not have guanine isomer not substantially because it can be separated.

Work as Y ¹And Y ²When being aralkoxy (as: benzyloxy), going to protect and under common hydrogenization condition, to be undertaken, work as Y by hydrogenolysis ¹Or Y ²One of when representing acyloxy or halogen, under general hydrolysising condition, this blocking group just can be selectively removed.

Transfer hydrogenation also can be used, as: in appropriate solvent (as: tetrahydrobenzene), the hydrogenation reaction on the palladium catalyst (palladium hydroxide) wherein must be used the solubility promoter that contains ethanol or Virahol, because can increase the solvability of affixture.

Hydrogenolysis is preferably carried out as follows: the ganciclovir that will protect is dissolved in the appropriate solvent system under conventional hydrogenation conditions; moulding pressure is 5-100psi (0.35-7atm); preferred 10-4psi (0.7-2.8atm); there is (as: the palladium hydroxide on carbon at catalyzer such as palladium compound; be also referred to as the Pearlman catalyzer) under, in about 20 °-60 ℃, preferred 20 °-35 ℃; react, carry out fully up to reaction.Other suitable hydrogenation catalyst comprises palladium, palladium carbon and its homologue catalyzer; Solvent systems also comprises low-grade alkane alcohol (as: methyl alcohol, ethanol).In general, reaction will carried out (as: backflow alcoholic acid temperature under hydrogen and excluding air pressure) between the reflux temperature of room temperature and solvent systems.Reaction vessel was preferably used nitrogen wash earlier before hydrogenation.Catalyzer will be filtered recovery.Evaporate excessive solvent to reduce the volume of filtrate, contain the raw material that does not have reaction in the crude product mixture usually, but most product is the ganciclovir product of 2-amido protecting that has the aliphatic hydroxyl of a protection.Separating step known in the art such as chromatography are adopted in the separation of these two products usually; preferred silica gel chromatography; mixture (preferred alcohol and the methylene dichloride) wash-out of the lower alkyl that replaces with suitable eluent such as low-grade alkane alcohol and halogen then, thus obtain having the ganciclovir product of the 2-amido protecting of an aliphatic hydroxyl protection.Then, this ganciclovir intermediate can separate by method in common as formula VI salt compound, as usefulness hydrogenchloride with as methanol solvent.

The hydrolysis reaction ganciclovir that preferably processing is protected under the alkaline hydrolysis condition of removing the acyl group hydroxyl protecting group carries out.

Hydrolysis medium comprises lower alkyl alcohol (as: methyl alcohol or ethanol), toluene, and aqueous sodium hydroxide solution.In general, be reflected between the reflux temperature of room temperature and solvent systems and carry out, ganciclovir intermediate such as above-mentioned method are separated with formula V compound salt.

For example, from the product alkaline purification that the step I obtains, remove lower acyl (as: Y ¹Base), partly gone protection.After the step I was finished, reaction mixture was cooled, and dilution (particular methanol) adds aqueous sodium hydroxide solution, reaction mixture is heated to 40-90 ℃ (preferred 60-80 ℃), and to reacting completely, reaction mixture is carefully used hcl acidifying then, filter and collect hydrochloride product, washing, drying.

The step III:

In this step, the L-Xie Ansuan activated derivatives of formula VI or VI a amido protecting carries out esterification with the ganciclovir salt derivative of the formula V monohydroxy that obtains protection in the step II.The amino protecting group of suitable L valine derivative has N-benzyloxy-carbonyl and N-(9-fluorenyl methoxy carbonyl) or " FMOC " group.

To contain organic bases (preferred TEA) step II product (formula VI compound) and be added in the proton inertia solution (preferred dimethyl formamide) of the L-Xie Ansuan activated derivatives of equivalent the preferred Z-Xie Ansuan of the activated derivatives of L-Xie Ansuan-N-carboxylic acid anhydride or L-Xie Ansuan acid anhydride in the suspension of aprotic solvent (preferred dimethyl formamide).Reaction mixture reacted 1-5 hour at 0-40 ℃ (preferred 4-10 ℃), dilute with water (preferred toluene and water).Filter collecting precipitation, washing, dry at ambient temperature.

Step IV (go protection at last, obtain formula I product)

The Xie Ansuan protecting group of step III product, hydroxyl protecting group Y ²And the amino guanine protecting group of optionally any 2-removes by protective reaction, preferably carries out in acidic medium or solvent, most preferably finishes by hydrogenation.Preferably in the acidic conditions protection of going down, because it will make amino protonated that protective reaction produces, the formula I alkali that promptly forms in the protective reaction will be by stoichiometric at least acid seizure.Isolating formula I idic acid additive salt is with the steric configuration of protection I compound.Therefore, the following example that goes to protect in the step and lifted has also shown the formation step of the salt that accompanies.

The protective reaction step is as follows: the product of step of esterification is dissolved in the inert solvent; the preferred acidic solvent; with hydrogenation catalyst (as: palladium/carbon; or palladium hydroxide/carbon; be Pearlman ' s catalyzer); pressurized with hydrogen is at 1-2000psi (0.07-140atm), preferred 20-200psi (1.4-14atm).Analyze the degree of carrying out of monitoring reaction with general TLC, can add hydrogenation catalyst if desired, filtration catalizer, washing, merging filtrate, concentrated cleaning solution, freeze-drying obtain the L-L-valine ester of ganciclovir.The purifying of product separates with crystalline and can adopt recrystallization or other purification process (as: liquid chromatography) to finish.

Owing to there is impurity (catalyst toxicity agent) the hydrogenation speed that can slow down in the initiator, now had been found that before carrying out hydrogenation with initiator in methyl alcohol with commercially available filtering product (as: catalytic Filtrol -highly acid activation potter's clay; Solka Floc -Solka-floc, activated carbon is as ADP carbon) to handle be useful.This can remove most of catalyst toxicity agent effectively.

If tert-butoxycarbonyl is used as amino protecting group, then just can go protection effectively with acid, as the HCl in Virahol, or only use trichoroacetic acid(TCA).

Perhaps; if step of esterification is to finish with the ganciclovir derivative of the trityl as protecting group of trityl or replacement; then can be in-20 ℃ of-100 ℃ of temperature ranges, handle and go protection with paraffinic acid or trifluoroacetic acid or aqueous hydrochloric acid (as: acetic acid aqueous solution).

The preparation of salt

Know, use one of common technology, formula I compound can be become acid salt or corresponding free alkali., preparation acid salt, then available suitable alkali (as: solution of ammonium hydroxide, sodium hydroxid, potassium hydroxide etc.) obtain free alkali if handling.Yet, it is worthy of note that especially the free alkali of formula I is than its sour additive salt its feature that more is hard to keep.If free alkali is transformed into acid salt, can adopt suitable organic or inorganic acid (the existing description) to react with it and finish.For these reactions are carried out smoothly, to use stoichiometric suitable acid (in the preparation acid salt) at least, or alkali (in release type I free cpds).In the typical in the present invention salt formation step, free alkali is dissolved in polar solvent (as: water or low-grade alkane alcohol, preferred Virahol, or their mixture) in, add the acid in an amount of water-soluble or low-grade alkane alcohol, temperature of reaction remains on 0-50 ℃ usually, preferred room temperature.The corresponding salt natural sedimentation that generates, or by adding the solvent of low-pole, evaporating solvent or vacuum are removed solvent or are passed through cooling solution, and make the salt precipitation.

The separation of steric isomer and 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl) methoxyl group-3-hydroxyl-1-propyl group-L-Xie Ansuan salt crystalline preparation

The unsymmetrical carbon in the L-Xie Ansuan, the formula I compound also has a unsymmetrical carbon (chiral centre) on the propyl group chain, therefore, has two diastereomers, press the regular called after (R) of Cahn-with (S)-type.The method of suitable separation diastereomer is described in european patent application No.694.547 to some extent, and is for reference.

The formula I compound also can be prepared into crystal type, and with respect to non-crystalline type, crystal type has many advantages.The suitable preparation method of The compounds of this invention crystal type is referring to U.S. Patent application No.281, and 893, it inserts as a reference at this.

Following preparation method and embodiment will make those skilled in the art more clearly understand and implement the present invention.They should not be considered to limit the scope of the invention, its just as an illustration with representative.

Embodiment 1

The preparation of (1A.2-2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-propyl group-1-propionyl ester

Trifluoromethanesulfonic acid (0.5ml) is added in the guanine (25g), and mixture is simply shaken to be stirred, and adds hexa methoxy disilazane (HMDS) (125ml), is heated to backflow until becoming solution.Excessive HMDS is removed in vacuum distilling, the cooling residuum, add trifluoromethayl sulfonic acid (0.4ml) again, add 1-propionyloxy-2-propionyloxy methoxyl group-3-benzyloxy propane (70g) subsequently, mixture heating up to 110 ℃-130 ℃ of a few hours are till HPLC detects less than guanine, cooling, with toluene (150ml) and methyl alcohol (21ml) dilution, carefully add entry (20ml), then cooling mixture.Collect with filter method, with toluene and water washing, drying.

The preparation of (1B.2-2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-propyl group-1-acetic ester

Trifluoromethanesulfonic acid (0.5ml) is added in the guanine (25g), and mixture is added hexa methoxy disilazane (HMDS) (125ml) by simple agitation, is heated to backflow until becoming solution.Excessive HMDS is removed in vacuum distilling, the cooling residuum, add trifluoromethanesulfonic acid (0.4ml) again, add 1-acetoxyl group-2-acetoxyl group methoxyl group-3-benzyloxy propane (65g) subsequently, mixture heating up to 110 ℃-130 ℃ of a few hours are till HPLC detects less than guanine, cooling, with toluene (75ml) dilution, carefully add entry (25ml), then cooling mixture.Collect ethanoyl monobenzyl ganciclovir (38g) with filter method, with toluene and water washing, drying.

(1C.2-2-ethanoyl-amino-1,6-dihydro-6-oxidation-purine-9-yl)-methoxyl group-1, the preparation of 3-benzyloxy-propane

Similar fully to the described method of embodiment 1A and 1B; react as glycerine reagent and 2-N-ethanoyl-guanine with 1-benzyloxy-2-acetoxyl group methoxyl group-3-benzyloxy propane and to prepare 2-(2-ethanoyl-amino-1; 6-dihydro-6-oxo-purine-9-yl)-and methoxyl group-1,3-benzyloxy-propane.

Embodiment 2

The preparation of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-propyl group-1-alcohol hydrochloride

2A. the preparation of the ganciclovir intermediate (formula V compound) of single protection of salt form can directly make from embodiment 1A product, and is as follows:

With following modification by the separable monobenzyl ganciclovir hydrochloride product that obtains of the method steps of describing among the embodiment 1A.After reaction was finished, cooling was with methyl alcohol (250ml) dilution, add NaOH (23g), mixture is fully stirred, heating, after hydrolysis fully (use HPLC, TLC detects), cooling mixture, add concentrated hydrochloric acid (45.2g), filter, with ethyl acetate (240ml) dilute filtration liquid, product is collected in cooling, washs with ethyl acetate, drying gets product 30.0g.

2B. similar with it, from ethanoyl monobenzyl ganciclovir (embodiment 1B product) preparation monobenzyl ganciclovir hydrochloride.Concrete steps are heating sodium hydroxide (10.0g); methyl alcohol (150ml) and ethanoyl monobenzyl ganciclovir (49g) mixture are until reacting completely; with hydrochloric acid (31g) souring soln; filter, with ethyl acetate (750ml) dilution filtrate, cooling; filter and collect product; with the ethyl acetate washing, drying gets product 47g.

Embodiment 3

The preparation of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-third-1-alcohol hydrochloride

3A. the preparation of single protection ganciclovir intermediate (formula V compound) of salt form also can pass through non-salt intermediate 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-third-1-alcohol or the monobenzyl ganciclovir is prepared as follows:

Use following modification step, from the separable monobenzyl ganciclovir that obtains of the method for among embodiment 1A, describing.After reaction was finished, cooling was with toluene (25ml) dilution, add the aqueous solution (125ml) of NaOH (25g), mixture is fully stirred, heating, after reaction is finished (HPLC, TLC detects), lower floor's water slowly is added to the acetone (125ml) of heat, in the mixture of acetate (25g) and water (25ml), fully stir, cooling, filtering separation obtains the monobenzyl ganciclovir, with the aqueous acetone solution washing, dry then.

Then, mix with concentrated hydrochloric acid (5ml) and methyl alcohol (80ml) from monobenzyl ganciclovir (17g), preparation monobenzyl ganciclovir hydrochloride, warmly all dissolve, with ethyl acetate (160ml) dilution, cooling until all solids, filter and collect product, with the ethyl acetate washing, drying gets product 18.1g.

The preferred solvent for preparing monobenzyl ganciclovir hydrochloride from the monobenzyl ganciclovir is a methyl alcohol, and other solvent also can be used by the same manner, and they are Virahols, ethanol and butanols.

3B. or be prepared as follows monobenzyl ganciclovir and monobenzyl ganciclovir hydrochloride from embodiment 1B product:

With following modification by the separable monobenzyl ganciclovir that obtains of the method for describing among the embodiment 1A.After reaction was finished, cooling was with toluene (25ml) dilution, add the aqueous solution (125ml) of NaOH (25g), mixture is fully stirred, heating, after reaction is finished (HPLC, TLC detects), lower floor's water slowly is added to the acetone (125ml) of heat, in the mixture of acetate (25g) and water (25ml), fully stir cooling, filtering separation obtains the monobenzyl ganciclovir, with the aqueous acetone solution washing, drying gets product 41g.

Be used in the similar method of describing among the embodiment 3A, prepare monobenzyl ganciclovir hydrochloride from the monobenzyl ganciclovir.

3C. or be prepared as follows monobenzyl ganciclovir and monobenzyl ganciclovir hydrochloride from embodiment 1C product.In this embodiment, embodiment 1C product is the dibenzyl ganciclovir intermediate of formula IV 2-amido protecting:

At first, N-ethanoyl-dibenzyl-ganciclovir is transformed into N-ethanoyl-monobenzyl-ganciclovir.N-ethanoyl-dibenzyl-ganciclovir (14.5kg) placed contain 60.1kg methyl alcohol, in 200 liters of glass reactors of 900g Pearlman ' s catalyzer, feed hydrogen, be heated to 40 ℃, 11 hours.Remove by filter catalyzer with Solka Floc cake, use 60kg washed with methanol cake again, methyl alcohol (60kg) is removed in distillation from N-ethanoyl-dibenzyl-ganciclovir and N-ethanoyl-monobenzyl-ganciclovir solution.Add water (113kg) in dense methanol solution, be cooled to 5 ℃, spend the night.Remove by filter N-ethanoyl-dibenzyl-ganciclovir then; with 140l methanol (6: 4) solution washing; merge methanol/water solution; under 115 ℃ outer sheath temperature; under 27ins (685.8mmHg) pressure; temperature in 44 ℃ of containers, underpressure distillation is up to steaming the 260kg methanol; water extracts three times (each dichloromethane extraction liquid all contains 3.75l ethanol) with methylene dichloride 100kg; combined dichloromethane and methylene dichloride/ethanol liquid 40 ℃ of jar normal temperature and pressure distillations, adds acetone (7.3l) in resistates; be heated to 50 ℃; stir, be cooled to 5 ℃, spend the night.Leach solid, with 15l (5 ℃ to-10 ℃) washing with acetone, vacuum-drying (about 50 ℃, 25ins Hg, nitrogen atmosphere) 24 hours obtains 3.425kg N-ethanoyl-monobenzyl-ganciclovir.Separation rate 29%.N-ethanoyl-monobenzyl-ganciclovir of HPLC:91.7%, 2.3% monobenzyl ganciclovir, N-ethanoyl-ganciclovir of 0.3%.

N-ethanoyl-monobenzyl-ganciclovir ammonia is separated and is become monobenzyl-ganciclovir: 103g N-ethanoyl-monobenzyl-ganciclovir is added in the ammonia soln of 500ml methyl alcohol and 100ml 30%; about 22 hours react completely (detecting) with TLC; at 40 ℃, under the condition of 28ins Hg, evaporative removal methyl alcohol; the aqueous solution is cooled to room temperature; filter, with 500ml water washing solid, (approximately-50 ℃ of vacuum-dryings; 25ins Hg, the nitrogen atmosphere) spend the night.Product weight: 94.1g.HPLC:95.5% monobenzyl ganciclovir.

The hydrochloride that can prepare then, the monobenzyl ganciclovir from the monobenzyl ganciclovir by the similar method described in the embodiment 3A.

Embodiment 4

The preparation of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-third-1-alcohol hydrochloride

4A. the preparation of single protection ganciclovir intermediate (formula V compound) of salt form also can be prepared as follows by intermediate 2-(2-propionyl-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-third-1-propionic ester of 2-amido protecting:

With following modification by method of describing among the embodiment 1A and the separable two propionyl monobenzyl ganciclovirs that obtain of product.After reaction is finished; cooling; propionic anhydride (31g) solution that adds 4-dimethyl-aminopyridine (1.6g), heating (is used HPLC fully until acylation reaction; TLC detects); add water (8.5g), with hexane (160ml) or hexane (160ml)/toluene (80ml) mixture extraction should heat mixture, separate lower floor; dilute with toluene (150ml); water (1 * l25ml, 1 * 75ml) washes twice, with ethyl acetate (15ml) dilution; water (75ml) is washed again; with organic phase cooling and stirring, filter and collect product, use toluene wash; drying gets product 43g.

Prepare monobenzyl ganciclovir hydrochloride from two propionyl monobenzyl ganciclovirs; promptly by heating sodium hydroxide (20.0g); methyl alcohol (400ml) and two propionyl monobenzyl ganciclovir (112g) mixtures, filter with hydrochloric acid (73.5g) souring soln until reacting completely; with ethyl acetate (800ml) dilution filtrate; cooling is filtered and is collected product, washs with ethyl acetate; drying gets product 76.7g.

4B. also can prepare the monobenzyl ganciclovir from two propionyl monobenzyl ganciclovirs; method is as follows: with sodium hydroxide (7g); water (80ml) and two propionyl monobenzyl ganciclovir (22.9g) mixture heating up are until reacting completely; the mixture that adds acetate (10g) and water (20ml) again; cooling is then filtered and is collected product, washes with water; drying gets product 17.1g.

Embodiment 5

The preparation of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-benzyloxy-1-propyl group-N-(benzyloxycarbonyl)-L-L-valine ester

5A. prepare the single L-valine ester of N-CBZ--monobenzyl ganciclovir (CBZ=carbonyl benzyloxy=benzyloxy acyl group from the monobenzyl ganciclovir; generally be abbreviated as Z); promptly be added to triethylamine (0.2g) by dimethyl formamide (2ml) solution with CBZ-L-Xie Ansuan-N-carboxylic acid anhydride (2.0g); in the mixed solution of dimethyl formamide (2ml) and monobenzyl ganciclovir (2.0g); use more triethylamines (0.2g) then; the mixed solution dilution of toluene (2.4ml) and water (8ml); vigorous stirring causes crystallization; add water (8ml); cooling is filtered and is collected product, washes with water; drying gets product 3.1g.

5B. or, also can prepare the single L-valine ester of N-CBZ--monobenzyl ganciclovir from the monobenzyl ganciclovir, being about to CBZ-L-Xie Ansuan acid anhydride [is added to dicyclohexyl carbodiimide (36.0g) in the stirring the mixture of CBZ-L-Xie Ansuan (97.2g) and ethyl acetate (280ml), stirring is spent the night, filter, wash with ethyl acetate (150ml), discard filtrate, decorating film is dissolved in the dimethyl formamide] (2.0g) dimethyl formamide (50ml) solution is added to 4-dimethylamino-pyridine (3.8g), in the mixed solution of dimethyl formamide (50ml) and monobenzyl ganciclovir (47.0g).The stirred overnight mixture filters, and (150ml) washes with ethyl acetate.Evaporated filtrate is dissolved in resistates in the dimethyl formamide as mentioned above.After reaction is finished, use triethylamine (20g), toluene (50ml) and water (200ml) diluted mixture thing, vigorous stirring causes crystallization, adds water (200ml), and cooling is filtered and is collected product, washes with water, and drying gets product 87.4g.

5C. also can prepare the single L-valine ester of N-CBZ--monobenzyl ganciclovir from monobenzyl ganciclovir hydrochloride as follows.Under 4-7 ℃ of nitrogen atmosphere condition, the O-monobenzyl ganciclovir hydrochloride (25.0g that past mechanical stirring, 66.8mmols) the suspension of dimethyl formamide (23ml) in add triethylamine (7.4g, 87mmols), control adding speed, make the soup compound temperature be no more than 8 ℃, finish in case add, just with Z-Xie Ansuan-NCA (24.0g, dimethyl formamide 86mmols) (23ml) solution splashes in the suspension of 4-6 ℃ of stirring, then, removes ice bath, make mixture temperature return to room temperature (23-25 ℃ approximately needs 30-45 minute).The TLC of mixture (80: 10: 8 CH ₃CN: CH ₃COOH: H ₂O) detected result shows that reaction is complete.At 23-25 ℃, (2.2g, 21.7mmols) adding of the success of the mixture of toluene (17.5ml) and water (20ml) will realize under the condition of 40-46 ℃ of heating triethylamine.(80ml) splashes in the mixture with extra water, made mixture slowly cool to 23-25 ℃ with more than two hours then, with 10-15 minute, water (100ml) is added in the mixture of medium vigorous stirring, continue to stir 10-15 minute behind the one-tenth solid, filter collecting precipitation then, water (each 50ml) washes twice, and dry air 3 hours is at 35-40 ℃, vacuum is removed residual toluene, gets product 39.3g (100%).

5D. also can prepare the single L-valine ester of the N-CBZ--monobenzyl ganciclovir of ultra-high purity as follows from monobenzyl ganciclovir hydrochloride.CBZ-Xie Ansuan-NCA (1.15 equivalent) is dissolved in ethyl acetate, at 23-25 ℃, in the presence of 4-dimethylaminopyridine (3% weight ratio), be added in the dimethyl formamide (DMF) and ethyl acetate suspension of monobenzyl ganciclovir (1.0 equivalent), stir after 3 hours,, continue to stir until reacting completely with the degree of carrying out of HPLC detection reaction, add the water termination reaction, with the ethyl acetate dilution, separate organic phase, use the ethyl acetate extraction water, combined ethyl acetate, wash twice with water, handle with activated carbon (as: PWA carbon), filter then at 35-40 ℃, in azeotropic drying, be concentrated into original volume.Add hexane lentamente at 89 ℃, being cooled to 25 ℃ more lentamente produces until crystal, method with decant is removed mother liquor, with twice of ethyl acetate/hexane (4/3) solution washing product, with hexane wash once, method with decant is removed the ethyl acetate/hexane washings, filters and obtains pure product,＜45 ℃ of dryings.

Embodiment 6

The preparation of the hydrochloride of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester

Can prepare ganciclovir-L-L-valine ester hydrochloride from the single L-valine ester of N-CBZ--monobenzyl ganciclovir as follows.Under the condition that palladium hydroxide/carbon (Pearlman catalyzer) (2.7g) exists, methyl alcohol (100ml) solution and the concentrated hydrochloric acid (2.7g) of initiator (14.2g) carry out hydrogenation, after reaction is finished, filter and collect filtrate, vacuum removal solvent makes and becomes small volume, add water (9g), remove residual methanol again, add Virahol (35ml), the vigorous stirring mixture produces until crystallization, add Virahol (55ml) again, stir, cooling, filter and collect product, use washed with isopropyl alcohol, drying gets product 8.0g; MS:355 (MH) ⁺

Claims (10)

1.2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester, or its pharmaceutical salts, or the preparation method of its diastereomer comprise following any one method or any bonded method:

(a) guanine that the following formula selectivity is replaced is with optionally high silylation form, wherein P ¹

Represent hydrogen atom or amino protecting group and following formula 2-substituted glycerol derivative under the condition that Lewis acid catalyst selectivity exists, carry out condensation reaction

Y wherein ¹And Y ²Be respectively halogen, low-grade acyloxy, or the aralkoxy of selectivity replacement, or Y ¹Or Y ²In have one to be valyl oxygen base; the Z representative is selected from low-grade acyloxy; methoxyl group, sec.-propyl, benzyloxy; halogen; methylsulfonyl, the leavings group of tosyl group obtains 2-(2-amino-1; 6-dihydro-6-oxo-purine-9-yl)-and methoxyl group-3-hydroxyl-1-propionyl-L-L-valine ester compound, represent with following formula:

P wherein ¹, Y ¹And Y ²Definition as above;

(b) work as Y ¹And Y ²When being aralkoxy, remove Y with hydrogenolysis ¹, Y ²One of in, if Y ¹, Y ²In one of be acyloxy or halogen, then remove, and next or simultaneously be transformed into acid salt with general basic hydrolysis;

(c) if desired, the activated derivatives of available L-Xie Ansuan and step (b) product carries out esterification; (d) selective removal amino and/or hydroxyl protecting group from following formula: compound

P wherein ¹Representation hydroxy protecting group or hydrogen atom, P ²Represent amino protecting group, Y ²Define as above, thereby obtain 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester compound or pharmaceutically acceptable salt thereof;

(e) optionally 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester is transformed into its pharmaceutical salts;

(f) optionally the acid salt of 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester is transformed into non-salt pattern;

(g) selectivity is made (R) of ester and (S) diastereomer with 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-Xie Ansuan diastereo-isomerism branch.

2. claim 1 method, wherein L-Xie Ansuan activated derivatives is Z-Xie Ansuan-N-carboxylic acid anhydride.

3. claim 1 method, wherein glycerol derivative is 1-propionyloxy-2-propionyloxy methoxyl group-3-benzyloxy propane, 1-acetoxyl group-2-acetoxyl group methoxyl group-3-benzyloxy propane or 1-benzyloxy-2-acetoxyl group methoxyl group-3-benzyloxy propane.

4. claims method, wherein step (a) product further uses the acid anhydrides (preferred propionic anhydride or diacetyl oxide) of 1-4 carbon atom to handle.

5. following formula: compound

P wherein ¹Be amino protecting group, it is the lower acyl of 1-4 carbon atom, Y ¹Represent halogen, the aralkoxy that low-grade acyloxy or selectivity replace, Y ²Represent the low-grade acyloxy of 1-4 carbon atom.

6. the compound in claims 5, wherein P ¹Represent propionyl, Y ²Represent propionyloxy or P ¹Represent ethanoyl, Y ²Represent acetoxyl group.

7. the preparation method of the compound in claims 5 comprises:

(a) replace and the guanine high silanization form of selectivity as shown in the formula selectivity

P wherein ¹Represent hydrogen atom, the condensation reaction of in the presence of Lewis acid selectivity, carrying out with following formula 2-substituted glycerol derivative

Y wherein ¹Represent halogen, low-grade acyloxy, or the aralkoxy of selectivity replacement, Y ²Represent the low-grade acyloxy of 1-4 carbon atom, the Z representative is selected from low-grade acyloxy, methoxyl group, sec.-propyl, benzyloxy, halogen, methylsulfonyl, the leavings group of tosyl group;

(b) acid anhydrides treatment step (a) product of 1-4 carbon atom of usefulness.

8. the method for claims 7, wherein acid anhydrides is propionic anhydride or diacetyl oxide.

9. following formula: compound

Wherein X represents salt formation group, Y ²Represent halogen, low-grade acyloxy, lower alkoxy, the aralkoxy that selectivity replaces, or valyl oxygen base, P ¹Represent hydrogen atom or amino protecting group.

10. the preparation method of the compound in claims 9 comprises:

(a) replace and the guanine high silylation of selectivity of following formula selectivity

P wherein ¹Represent hydrogen atom or amino protecting group, in the presence of the Lewis acid catalyst, carry out condensation reaction with following formula 2-substituted glycerol derivative

Y wherein ¹And Y ²Represent halogen respectively, low-grade acyloxy, or the aralkoxy of selectivity replacement, or Y ¹And Y ²One of represent valyl oxygen base, the Z representative is selected from low-grade acyloxy, methoxyl group, sec.-propyl, benzyloxy, halogen, methylsulfonyl, the leavings group of tosyl group obtains 2-(2-amino-1,6-dihydro-6-oxo-purine-9-yl)-methoxyl group-3-hydroxyl-1-propyl group-L-L-valine ester compound;

(b) work as Y ¹And Y ²When being aralkoxy, remove Y with hydrogenolysis ¹, Y ²One of in, if Y ¹, Y ²In one of be acyloxy or halogen, then remove, and be transformed into acid salt with basic hydrolysis.