Chemoenzymic Synthesis of Chiral Furan Derivatives: Useful Building Blocks for Optically Active Structures

Article abstract of DOI:10.1021/jo00243a003

Practical procedures have been developed for the enantioselective reduction of 2-acetylfuran (6a) and 2-(trifluoroacetyl)furan (6b) to the corresponding carbinols (S)-1 and 7b with 88-90percent ee using Thermoanaerobium brockii alcohol dehydrogenase coupled with an NADPH regeneration system.Kinetic resolution of racemic (S)-1 via lipase-catalyzed esterification, followed by cholesterol esterase or lipase-catalyzed hydrolysis of the ester gives (R)-1 with 94percent ee.Conversion of (S)-1 to the dihydropyranones 4 and 5 without racemization has been illustrated.Enantioselectivehydrolysis of N-protected furylglycine methyl esters catalyzed by papain gave the unreacted esters and and the free acids (S form) both in 45percent yield and 97percent ee.The resolved furylglycines are excellent substrates for the synthesis of optically active synthons for alkaloids.