57 クロチルシランの共役付加反応を利用した環外立体制御と天然有機化合物の立体選択的合成(ポスター発表の部)

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The extracyclic stereocontrol is a problem of current interest specially in connection with the stereoselective construction of steroid side chain. We have addressed this problem by the stereocontrolled addition of E- and Z-crotylsilanes to alkenones. The reaction was more or less stereospecific with respect to the double bond geometry of E and Z-crotylsilanes, being erythro- and threo-selective respectively. Modification of the silyl substituents, variation of the Lewis acid, presence of the addend and so on had some effect for the selectivity. The paper is composed of six parts of the investigations. (1) diastereoselectivities in the addition reactions of crotylsilanes to 2-cyclohexene. (2) stereodivergent synthesis of juvabione and epi-juvabione. (3) diastereoselectivities in the addition reactions of crotylsilanes to 2-substituted 2-cyclopentenones. (4) stereodivergent synthesis of neonepetalactone and isoneonepetalactone. (5) asymmeric addition reaction of crotylsilanes to 2-substituted 2-crotylsilanes with chiral auxiliaries at 2 position. (6) asymmetric synthesis of cholesterol C/D rings.
天然有機化合物討論会の論文
1990-09-25