Enantioselective Rhodium-Catalyzed [2+2+2] Cycloaddition of Alkenyl Isocyanates and Terminal Alkynes: Application to the Total Synthesis of (+)-Lasubine II
作者:Robert T. Yu、Tomislav Rovis
DOI:10.1021/ja064868m
日期:2006.9.1
The use of TADDOL-based phosphoramidite ligands on rhodium allows for the incorporation of terminal alkynes in the [2+2+2] cycloaddition with alkenyl isocyanates. Terminal aliphatic alkynes provide bicyclic lactams, while the use of aryl alkynes provides complementary access to vinylogous amides. Product selectivity seems to be governed by a combination of electronics and sterics, with smaller and/or
在铑上使用基于 TADDOL 的亚磷酰胺配体允许在与烯基异氰酸酯的 [2+2+2] 环加成中加入末端炔烃。末端脂肪族炔烃提供双环内酰胺,而芳基炔烃的使用提供了对乙烯基酰胺的补充访问。产品选择性似乎受电子学和空间学的组合控制,更小和/或更多缺电子取代基有利于内酰胺的形成。使用同源烯基异氰酸酯导致生物碱拉苏宾 II 的适宜的不对称全合成。