38 ニッケル触媒による新規環化反応の開発及びそのプロスタノイド合成への利用(口頭発表の部)

概要

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We have recently reported a novel stereoselective cyclization of 1,3-diene and the carbonyl group in a chain, in which the hydride nickel complex 2 plays an important role. By use of Et_3SiH as a hydride source, the catalytic cycle was established to produce 4, 9c, 10c, or 11c as a sole product. Further, we have also found that 1,3-diene serves as a ligand and affects the regio-selectivity in a side chain of the cyclized product. In the presence of 1,3-cyclohexadiene (1,3-CHD) (150mol %), the cyclized product 8, 9b, 10b, or 11b was produced predominantly. Using this cyclization, the synthesis of prostanoids was tried. The optically active substrate 13 was easily prepared via Sharpless epoxidation followed by regioselective ring opening reaction of resultant epoxide 20 with vinyl cuprate. The reaction of 13 with 2 (100mol %) in the presence of 1,3-CHD proceeded stereoselctively, affording the cyclized product 14 in 93% yield as a sole product. The cyclized product 14 was transformed into 28, which is a versatile intermediate for the synthesis of prostanoids. Further studies along this line are in progress.
天然有機化合物討論会の論文
1996-09-02