Research for Synthetic Utilization of Easily Available C_2-Symmetric Chiral Compounds

点击翻译按钮获取中文摘要

In the research supported by this grant for two years term from April 1990 to March 1992, we have succeeded in the total synthesis of antibiotic(+)-asperlin(4)with antitumore activity staring with(-)-tartaric acid(1). The strategy included derivation to and effective utilization of 6, 8-dioxabicyclo[3.2. lloctane skeleton(3)as a key intermediate which is transformed highly site- and stereoselectively, and will serve as a general synthetic method for optically active 6-substituted 5-hydroxy-5, 6-dihydro-2-pyrones. In the project for development of chiral reagents from tartaric acid, 0, 0dibenzoyl-tartarimide(5)was syntesized in a 3-steps sequence and a high yield, and derived to the N-bromoimide(6). Bromoetherification of styrene by use of the N-bromoimide(6)was tried but unsuccessful in chiral induction. D-Mannitol(2)was transformed in a 2-steps sequence to chiral C_2-symmetric pyrrolidine(7), which was converted in short-steps sequences into several kinds of C_2-symmetric pyrrolidines(8)and D_2-symmetric ones(9). Examination of these pyrrolidines as chiral catalyst ligands was performed in the addition reaction of diethylzinc to benzaldehyde and a high chiral induction of 82% ee was attained with one of these pyrrolidines. In the research for exploitation of new reagent for natural product synthesis, we found a combination system of ethyl cyanoformate/30% hydrogen peroxide as a useful olefin-epoxidizing system which appears to be very mild and applicable to substrates bearing acid-labile functional groups.