51 高立体選択的ヘテロジールスアルダー反応の開発とポリアミン系アルカロイドカンナビサチビンの合成への応用(口頭発表の部)

概要

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Face selectivity of Diels-Alder reaction of diene having the stereogenic center at allylic position depends on dienophile polarity, and we found that hetero Diels-Alder reaction with dienophile such as N-tosylimine and N-tosylsulfinylimine give exclusively ul product. The empirical rule of the face selectivity of these reactions like following are proposed; pola dienophile prefer to give ul adduct, on the other hand, less polar dienophile prefer to give 1k adduct reacting with diene. The reaction mechanism is also proposed as following; more polar dinophile react with the chiral diene to give dipolar intermediate and the intermediate is stabilized by lone pair of oxigen or nitrogen through homoallylic interaction to give ul adduct preferencially, on the other hand, with lass polar dienophile, the transition state is mainly governed by stable conformation of reactant diene. As an aplication of this highly diastereoface-selective reaction, polyamine alkaloid Cannabisativine was synthesized as an optical active form. The key step is hetero Diels-Alder of chiral diene and N-tosylimine, regio and diastereo-face selectivity is completely controlled, only one diastereomer was isolated in high yield.
天然有機化合物討論会の論文
1990-09-25