Synthesis of Racemic and Optically Active Cispentacin (FR109615) Using Intramolecular Nitrone-Olefin Cycloaddition.
作者:Toshiyuki KONOSU、Sadao OIDA
DOI:10.1248/cpb.41.1012
日期:——
Synthesis of racemic and optically active cispentacin ((-)-1) is described. Intramolecular nitrone-olefin cycloaddition of the alkenyl nitrone 7 gave cis-isoxazolidine (±)-8, which was transformed into (±)-1 by sequential reactions involving catalytic hydrogenolysis and oxidation. Similarly, the optically active nitrone (R)-22, which was derived from the ketone 15 via lipase-catalyzed hydrolysis of the acetate (±)-17, underwent intramolecular cycloaddition to give (+)-25 with high stereoselectivity (15 : 1). The cycloadduct (+)-25 was transformed in 4 steps into optically active natural cispentacin.
本文介绍了外消旋且具有光学活性的西苯达辛((-)-1)的合成。烯基腈酮 7 分子内的硝酮-烯烃环加成反应产生了顺式异恶唑烷 (±)-8,通过催化氢解和氧化的连续反应,将其转化为 (±)-1。同样,光学活性腈酮 (R)-22 也是通过脂肪酶催化水解醋酸酯 (±)-17 从酮 15 中得到的,经过分子内环加成反应,以高立体选择性(15:1)得到 (+)-25。环加成产物 (+)-25 经过 4 个步骤转化为具有光学活性的天然西司喷丁。