P-51 テトラヒドロフラン誘導体の触媒的不斉合成法の研究(ポスター発表の部)

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Asymmetric synthesis of tetrahydrofuran derivatives has received much attention due to their ubiquitous presence in many naturally occurring biologically active substances. Although there have been reported many syntheses of optically active tetrahydrofuran derivatives, the methodologies used to date are limited to a few reactions: e.g., intramolecular haloetherification and acid-catalyzed cyclization of unsaturated alcohols and epoxy alcohols. Accordingly development of a new methodology for the efficient construction of tetrahydrofuran unit is still strongly required. In 1966, Nozaki et al. for the first time reported asymmetric cyclopropanation and C-O insertion reaction. Since then, many effective methodologies for catalytic asymmetric cyclopropanation have been reported but asymmetric C-O insertion reaction has been left without attracting chemist's notice, though it may provide a new entry to asymmetric synthesis of tetrahydrofuran derivatives. Recently, we found that the copper complex of chiral C2-symmetric bipyridine was an effective catalyst for asymmetric cyclopropanation. In the course of this study, we also examined the asymmetric ring expansion of oxetanes by using the carbene insertion reaction with diazoacetate in the presence of chiral copper-bipyrindine (1) complex and found that the insertion reaction proceeded with high enantiospecificity. For example, the reaction of (R)-2-phenyloxetane of 89%ee with t-butyl diazoacetate gave t-butyl (2S,3R)-3-phenyltetrahydrofuran-2-carboxylate of 92%ee preferentially, while that of (S)-2-phenyloxetane did (2S,3S)-3-phenyltetrahydrofuran-2-carboxylate of 93%ee. The synthesis of whisky lactone (6) has been achieved by using the newly developed asymmetric carbene insertion reaction.
天然有機化合物討論会の論文
1995-09-01

P-51 テトラヒドロフラン誘導体の触媒的不斉合成法の研究(ポスター発表の部)

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