Enantioselective Total Syntheses of (-)-Isonitramine, (-)-Sibirine, and (+)-Nitramine by Ring-Closing Metathesis
作者:Ganesh Pandey、C. Prasanna Kumara、Shiva Kumar Burugu、Vedavati G. Puranik
DOI:10.1002/ejoc.201101256
日期:2011.12
Concise enantioselective total syntheses of naturally occurring 2-azaspiro[5,5]undecan-7-ol (Nitraria) alkaloids viz. (–)-isonitramine, (–)-sibirine, and (+)-nitramine are accomplished in 42, 38, and 25 % overall yield, respectively, in six steps starting from enantiomerically pure (S)-methyl 3-allyl-2-oxo-1,2,3,6-tetrahydropyridine-3-carboxylate (>99 % ee). The key feature of the syntheses involves
天然存在的 2-azaspiro [5,5] undecan-7-ol (Nitraria) 生物碱的简明对映选择性全合成。(-) - 异硝胺、(-) - 锡伯林和 (+) - 硝胺分别以 42%、38% 和 25% 的总收率完成,从对映体纯的 (S) -甲基 3-烯丙基-2 开始,分六个步骤完成-oxo-1,2,3,6-tetrahydropyridine-3-carboxylate (> 99% ee)。合成的关键特征涉及非对映选择性的 Hosomi - Sakurai 烯丙基化,然后是闭环复分解。