| Research Abstract |
Enzymes are now recognized as substrate-specific and highly enantioselective catalyst for asymmetric synthesis. In particular, lipases have recently been used for biocatalytic resolutions on the basis of the admission of organic solvents as reaction media.We succeeded immobilized lipase-mediated resolution of N,N-dialky1-3-hydroxy-4-pentenamides, unsuccessful in resolution by the Katsuki-Sharpless asymmetric epoxidation. Iodolactonizaion of thus prepared homochiral amides and oxy-lactonization of O-protected homochiral amides proceeded stereoselectively, affording both enantiomers of cis-3,4-disubstituted gamma-lactone and both enantiomers of trans-3,4, disubstituted gamma-lactone preferentially, respectively.These gamma-lactones have been used as chiral building blocks for the synthesis of biological active compounds such as litsenolides, (+) -blastimycinone, NFX-2, NFX-4, metabolites from Gorgonian Plexaura flava, and muscarine.Especially, cis-3,4-disubstituted gamma-lactones were served as the masked butenolide chirons and a concise synthesis of (+) -trans-wisky and (+) -trans-cognac lactones, (-) -methylenolactocin, (+) -nephrosteranic acid, and (+) -roccellaric acid has been achieved.In addition, these gamma-lactones have been apllied as chiral carbon five building blocks for the synthesis of insect pheromons.
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