Optically Active Cyclohexene Derivative as a New Antisepsis Agent : An Efficient Synthesis of Ethyl (6R)-6-[N-(2-Chloro-4-fluorophenyl)-sulfamoyl] cyclohex-1-ene-1-carboxylate (TAK-242)

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Two new synthetic methods were established for the efficient synthesis of optically active cyclohexene antisepsis agent, ethyl (6R)-6-[N-(2-chloro-4-fluorophenyl) sulfamoyl] cyclohex-1-ene-1-carboxylate [(R)-1: TAK-242)]. The first method involved recrystallization from methanol of the diastereomeric mixture (6RS, 1'R)-7, obtained by esterification of carboxylic acid 3 with (S)-1-(4-nitrophenyl) ethanol [(S)-5)] to give the desired isomer (6R, 1'R)-7 with 99% de in 32% yield. Subsequent catalytic hydrogenolysis and esterification gave (R)-1 with >99% ee. The second method employed enantioselective hydrolysis of acetoxymethyl ester 9a (prepared by alkylation of 3 with bromomethyl acetate) with Lipase PS-D to give the eutomeric enantiomer (R)-9a with excellent enantiose-lectivity (>99% ee) and high yield (48%). The desired (R)-1 was then obtained by transesterification with ethanol in the presence of concentrated sulfuric acid without loss of ee. Of these, the procedure employing enzymatic kinetic resolution using Lipase PS-D is the more efficient and practical preparation of (R)-1.
公益社団法人日本薬学会の論文
2006-01-01