合成路线1

The reaction of D-methionine (I) with tert-butoxycarbonyl anhydride and NaOH in water gives the N-protected compound (II), which is treated with more tert-butoxycarbonyl anhydride and ammonium bicarbonate in pyridine/DMF yielding The N-protected methioninamide (III). The protection of the amide group of (III) with benzyloxycarbonyl chloride and BuLi in THF affords the fully protected methioninamidde (IV), which by reaction with methyl iodide in acetone or acetonitrile gives the dimethylsulfonium iodide (V). The cyclization of (V) by means of DOWEX 2X8-400 (hydroxide form) yields the protected 3-aminopyrrolidinone (VI), which by selective deprotection with HCl followed by acylation with methyl trifluoroacetate and NaHCO3 affords N-[1-(benzyloxycarbonyl)-2-oxopyrrolidin-3(R)-yl]trifluoroacetamide (VII). The reduction of the carbonyl group of (VII) with LiBH4 in THF provides the pyrrolidinol (VIII), which is treated with ethanol and conc. H2SO4 giving the ethyl ether (IX). The condensation of (IX) with the triisopropylsilyl derivative of ethyl 3-methylbutyrate (X) by means of BF3 ethearate in dichloromethane yields the 2-pyrrolidinylbutyrate (XI) as predominant isomer, which is destrifluoroacetylated with K2CO3 in refluxing ethanol/water affording aminopyrrolidine (XII). The cyclization of (XII) by means of tert-butylmagnesium chloride in THF gives a mixture of bicyclic pyrrolidones, from which the chiral isomer (XIII) was separated by crystallization. The mesylation of (XIII) with methanesulfonyl chloride and lithium hexamethyldisylazane in THF affords the sulfonamide (XIV), which is deprotected by hydrogenation with H2 over Pd(OH)2 in ethyl acetate/dioxane giving the bicyclic pyrrolidone (XV), which is finally acylated with 4-(1-piperidinyl)-2(E)-butenoic acid (XVI) by means of HOBT and triethylamine in acetonitrile or oxlayl chloride in dichloromethane.