合成路线1

A new synthesis of Sch-51048 based on a known key intermediate has been described:The reaction of (I) (the final product in Tetrahedron Lett 1995, 36(11): 1787, or intermediate (II) in the synthesis published in the original monograph) with 4-[4-(4-nitrophenyl)piperazin-1-yl]phenol (II) (obtained from the corresponding anisole (III) with 48% HBr) by means of NaOH in DMSO yields the corresponding condensation product (IV). The reduction of the NO2 group of (IV) with H2 over Pd/C in ethanol affords the amine (V), which is acylated with phenyl chloroformate and pyridine to the corresponding carbamate (VI). The reaction of (VI) with hydrazine in dimethoxyethane affords the semicarbazide (VII), which is cyclized with formamidine acetate in 2-methoxyethanol to the triazolinone (VIII). Finally, this compound is alkylated with 3-bromopentane and NaOH in DMSO or DMF.

合成路线2

Synthesis of intermediate (XX): The reaction of 2-chloro-2',4'-difluoroacetophenone (I) with sodium acetate and NaI in DMF gives 2-acetoxy-2',4'-difluoroacetophenone (II), which by methylenation with methyltriphenylphosphonium bromide and sodium bis(trimethylsilyl)amide in THF yields 2-(2,4-difluorophenyl)-2-propen-1-ol acetate ester (III). The hydrolysis of (III) with KOH in dioxane/water affords the corresponding alcohol (IV), which is regioselectively epoxidized with titanium tetraisopropoxide and L-(+)-diethyl tartrate in dichloromethane to (S)-(-)-2-(2,4-difluorophenyl)oxirane-2-methanol (V). The reaction of (V) with 1,2,4-triazole (VI) in DMF affords (R)-2-(2,4-difluorophenyl)-3-(1,2,4-triazol-1-yl)propane-1,2-diol (VII), which is selectively mesylated with methanesulfonyl chloride and triethylamine to the monomesylate (VIII). The cyclization of (VIII) with NaH in DMF gives the oxirane (IX), which is condensed with diethyl malonate (X) by means of NaH in DMSO to yield a mixture of (5R-cis)- and (5R-trans)-5-(2,4-difluorophenyl)-2-oxo-5-(1,2,4-triazol-1-ylmethyl) tetrahydrofuran-3-carboxylic acid ethyl ester (XI). The reduction of (XI) with NaBH4 and LiCl in ethanol affords (R)-4-(2,4-difluorophenyl)-2-(hydroxymethyl)-5-(1,2,4-triazol-1-yl) pentane-1,4-diol (XII), which is selectively tosylated with tosyl chloride and triethylamine in THF to the bistosylate (XIII). The cyclization of (XIII) by means of NaH in refluxing toluene gives (5R-cis)-5-(2,4-difluorophenyl)-5-(1,2,4-triazol-1-ylmethyl) tetrahydrofuran-3-methanol tosylate ester (XIV). The reaction of (XIV) with 1-(4-hydroxyphenyl)-4-(4-nitrophenyl)piperazine (XV) to obtain compound (XVI), and the following reaction sequence (XVI) to (XVII) to (XVIII) to (XIX) to (5R-cis)-4-[4-[4-[4-[5-(2,4-difluorophenyl)-5-(1,2,4-triazol-1-ylmethyl)tetrahydrofuran-3-ylmethoxy]phenyl]piperazin-1-yl]phenyl-3,4-dihydro-2H-1,2,4-triazol-3-one (XX) has been performed according to J Med Chem 1984, 27: 894-900.

合成路线3

The bromosulfonate (XXI) has been obtained as follows: (S)-Lactic acid methyl ester (XXII) has been protected as its benzyloxymethyl ether (XXIII) according to Tetrahedron Lett 1980, 21: 1035. The reduction of (XXIII) with DIBAL yields the corresponding aldehyde (XXIV), which by a Grignard reaction with ethylmagnesium bromide in THF and chromatographic separation of the diastereoisomers (SiO2, hexane/ethyl acetate) affords 2(S)-(benzyloxymethoxy)-3(R)-pentanol (XXV). Finally, this compound is sulfonated to (XXI) with 4-bromobenzenesulfonyl chloride. Finally, compound (XX) is condensed with 2(S)-(benzyloxymethoxy)-3(R)-pentanol 4-bromobenzenesulfonate ester (XXI) by means of cesium carbonate in DMF, and deprotected with 6N HCl.

合成路线4

The synthesis of [14C]-SCH-56592 has been described: The cyclization of semicarbazide (I) with [14C]-formamidine (II) in hot 2-methoxyethanol gives the triazolone (III), which is condensed with the sulfonate (IV) by means of Cs2CO3 in hot DMF to yield the alkylated triazolone (V). Finally, this compound is deprotected by hydrogenation with formic acid over Pd/C in hot methanol to afford labeled SCH-56592.

合成路线5

Coupling of tosylate (XIII) with the sodium salt of phenol (XX) produced ether (XXI). The nitro group of (XXI) was then reduced to amine (XXII) by hydrogenation over Pt/C. Subsequent condensation of (XXII) with phenyl chloroformate in pyridine afforded the phenyl carbamate (XXIII), which was reacted with hydrazine to yield the semicarbazide derivative (XXIV). Ring closure of (XXIV) with formamidine acetate then provided triazolone (XXV).

合成路线6

Methyl (S)-lactate (XXVI) was protected as the benzyloxymethyl ether (XXVII) and subsequently reduced to aldehyde (XXVIII) with DIBAL in toluene at -78 C. Addition of ethylmagnesium bromide to this aldehyde (XXVIII) produced a diastereomeric mixture of carbinols. The required (2S,3R) isomer (XXIX) was isolated by column chromatography and then converted to brosylate ester (XXX) by reaction with 4-bromobenzenesulfonyl chloride. Nucleophilic displacement of the brosylate group of (XXX) by triazolone (XXV) produced the N-alkylated triazolone (XXXI). Then, acid cleavage of the benzyloxymethyl protec-ting group of (XXXI) provided alcohol (XXXII).

合成路线7