Enantioselective Thiourea-Catalyzed Additions to Oxocarbenium Ions
作者:Sarah E. Reisman、Abigail G. Doyle、Eric N. Jacobsen
DOI:10.1021/ja801514m
日期:2008.6.1
Asymmetric, catalytic reactions of oxocarbeniumions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbeniumion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities
A phosphane‐catalyzed [3+3] annulation of azomethineimines with ynones has been developed. Under mild reaction conditions, the reaction proceeds smoothly to afford tricyclic dinitrogen‐fused heterocyclic compounds in moderate to excellent yields with moderate to excellent stereoselectivies. Using a chiral phosphine as the catalyst, the reaction could work to give the cycloadduct in moderate yield