48(P06) 生体触媒を用いる含酸素天然有機化合物の合成(ポスター発表の部)

概要

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Oxygen-containing natural products such as (3aS, 6aS)-ethisolide 2 (a diastereomer of ethisolide 1), whisky lactone 3, and (-)-disparlure 5 were synthesized from α-chlorinated ketones by using biocatalysts such as bakers' yeast and lipase for key steps. All products showed high optical purities. (γS)-Butenolides 8 were prepared through the formation of optically active alcohol 7 from 3-chloro-4-oxoesters 6 with bakers' yeast reduction, and the subsequent hydrolysis, lactonization, and dehydrochlorination. In the case of the reduction of 6 possessing the large alkyl groups, the chemical yield of 7 was quite low. Then, reduction of 6 with sodium borohydride, and the subsequent optical resolution of the product (±)-7 with lipase gave both enantiomers of 7. Lactonization of the enantiomer afforded (γR)-butenolides 8. Total synthesis of (3aS, 6aS)-ethisolide 2 was established with high stereoselectivity via 3 steps, containing Michael addition to (S)-8 (R=C_2H_5). Furthermore, (-)-avenaciolide 4 was synthesized highly stereoselectively from (R)-8 by the same method. Reduction of ethyl 3-chloro-2-oxotridecanoate (13) with NaBH_4 gave ethyl syn-3-chloro-2-hydroxytridecanoate (14) in 92% yield. Treatment of 14 with lipase in the presence of vinyl acetate gave (2S, 3s)-14 in 43% yield with 9l%ec. Total synthesis of (-)-disparlure 5 was established via 4 steps from (2S, 3S)-14 in good yields.
天然有機化合物討論会の論文
1997-07-20