合成路线1

A new synthesis of Sch-56592 has been described: The reaction of (S)-ethyl lactate (I) with pyrrolidine (II) gives 1-[(S)-lactoyl]pyrrolidine (III), which is benzylated as usual with benzyl chloride yielding the benzyl ether (IV). The reaction of (IV) with ethylmagnesium bromide in THF affords 2(S)-benzyloxy-3-pentanone (V), which is reduced with LiBH4 in dimethoxyethane giving 2(S)-benzyloxy-3(RS)-pentanol (VI). The reaction of (VI) with 4-chlorobenzenesulfonyl chloride (VII) yields the corresponding sulfonate (VIII), which is treated with hydrazine in ethanol to afford a diastereomeric mixture of hydrazines that is resolved with L-dibenzoyltartaric acid giving the (S,S)-enantiomer (IX). The formylation of (IX) with refluxing ethyl formate yields the chiral formyl hydrazide (X), which is cyclized with N-[4-[4-[4-(trimethylsilyloxy)phenyl]piperazin-1-yl]phenyl]carbamic acid phenyl ester (XI) affording the triazolone (XII). Finally, this compound is condensed with the chiral tetrahydrofuran derivative (XIII) by means of NaOH in DMSO, and debenzylated by hydrogenation with H2 over Pd/C in formic acid

合成路线2

In an alternative synthesis of compound (XXXII), methyl (S)-lactate (XXXIII) was converted to amide (XXXIV) by treatment with pyrrolidine, and then protected as the benzyl ether (XXXV). Reduction of (XXXV) by means of sodium bis(methoxyethoxy)aluminum hydride produced aldehyde (XXXVI). Condensation of (XXXVI) with formic hydrazide produced the formyl hydrazone (XXXVII), to which was added ethylmagnesium bromide affording a mixture of diastereoisomeric hydrazides. Separation by column chromatography provided the required (S,S) isomer (XXXVIII). Cyclization of (XXXVIII) with the phenyl carbamate (XXIII) in the presence of DBU furnished the triazolone (XXXIX). This was deprotected by hydrogenation in the presence of Pd/C and formic acid to produce compound (XXXII)

合成路线3