天然有機化合物討論会講演要旨集
Online ISSN : 2433-1856
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14 マイケル付加を利用する隣接三級炭素の立体制御と天然物合成への応用
山口 雅彦塚本 美智徳田中 慎哉長谷部 浩一平尾 一郎
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会議録・要旨集 フリー

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Stereocontrolled construction of the adjacent tertiary carbons was examined using the Michael addition of ester and amide enolates to α,β-unsaturated esters. It was applied to the stereoselective synthesis of natural products possessing acyclic or extracyclic chiral centers. Reaction of lithiated propionates with crotonates in THF-HMPA at -78℃ gave erythro-2,3-dimethylglutarates highly selectively. Threo-isomers were synthesized by using t-butyl propionate (1b) in THF. A formal synthesis of faranal (6), the trail pheromone of monomorium pharaonis, was performed. When ω-halo-2-alkenoates (10) were treated with the enolate in the presence of t-BuOK, the Michael-induced intramolecular alkylation occurred smoothly. And cycloalkanes were obtained as a single isomer concerning three chiral centers containing an extracyclic center. (+)-Dehydroiridodiol (12), isolated from Actinidia polygama Miq. as an attractant for members of the Chrysopidae, and (+)-isodehydroiridodiol (13) were synthesized stereoselectively. The enolate of N-propionylpyrrolidine (18a) reacted with the unsaturated esters in ether to give threo-adducts. The other isomer was synthesized by using 2,5-trans-disubstituted pyrrolidine amide 18b. The asymmetric Michael addition was performed with (L)-N-methyl-N-propionylvalinol (18c), and, after the hydrolysis of ester and amide group, (2R,3R)-2,3-dimethylglutaric acid (erythro-22) was obtained. (L)-N-Propionyl-prolinol (18d) afforded (2R,3S)-acid (threo-22). The synthesis of (+)-12 and (-)-13 was achieved utilizing this methodology.

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© 1985 天然有機化合物討論会電子化委員会
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