P-44 アリールイリジウムサレン錯体を触媒とするシス選択的不斉シクロプロパン化反応の開発(2)とリゾフォスファチジン酸(PHYLPA)の合成研究(ポスター発表の部)

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Last year in this symposium, we reported that aryliridium-salen complexes (1 and 2) catalyzed highly enantio- and cis-selective cyclopropanation of conjugated terminal and cis-disubstituted olefins. In the subsequent study, it was found that this cyclopropanation could be applied to cyclopropanation of non-conjugated terminal olefins without diminishing enantio- and cis-selectivity. In addition, we could determine the structure of arylimidium-salen complex 2, which gave a possible explanation for unusual temperature effect presented in the symposium. Asymmetric cyclopropanation of non-conjugated terminal olefins provides a potent tool for preparing optically active cis-disubstituted cyclopropanes that are observed in various natural products. In order to explore this possibility, we tried the synthesis of cyclopropyl fatty acid methyl ester 7 starting from 1-ctene. Asymmetric cyclopropanation of 1-octene gave the cis-cyclopropanecarboxylate 3 in 41 % after the separation of the corresponding trans-isomer by silica gel chromatography. Compound 3 was converted into 7 via four steps in a 57% yield. It has been reported that the enantiomer of 7 can be converted into Lysophosphatidic acid (PHYLPA), a specific inhibitor of DNA polymerase α.
2007-08-24