Enantioselective Synthesis of Indolizidines Bearing Quaternary Substituted Stereocenters via Rhodium-Catalyzed [2 + 2 + 2] Cycloaddition of Alkenyl Isocyanates and Terminal Alkynes
作者:Ernest E. Lee、Tomislav Rovis
DOI:10.1021/ol800086s
日期:2008.3.1
An enantioselectivesynthesis of indolizidines bearing quaternary substituted stereocenters by way of a rhodium-catalyzed [2+2+2] cycloaddition of substituted alkenyl isocyanates and terminal alkynes is described. The reaction provides lactam products using aliphatic alkynes, whereas aryl alkynes give rise to vinylogous amide products. Through modification of the phosphoramidite ligand, high levels
Asymmetric Synthesis of Bicyclic Amidines via Rhodium-Catalyzed [2+2+2] Cycloaddition of Carbodiimides
作者:Robert T. Yu、Tomislav Rovis
DOI:10.1021/ja710065h
日期:2008.3.1
A highly enantioselective rhodium-catalyzed [2+2+2] cycloaddition of terminal alkynes and alkenyl carbodiimides has been developed. This reaction demonstrates the feasibility of olefin insertion into carbodiimide-derived metalacycles and provides a new class of chiral bicyclic amidines as the major products. An isonitrile migration process responsible for the formation of the minor cycloadduct can
Enantioselective Rhodium-Catalyzed [4+2+2] Cycloaddition of Dienyl Isocyanates for the Synthesis of Bicyclic Azocine Rings
作者:Robert T. Yu、Rebecca Keller Friedman、Tomislav Rovis
DOI:10.1021/ja906641d
日期:2009.9.23
A highly enantioselectiverhodium-catalyzed [4+2+2] cycloaddition of terminal alkynes and dienyl isocyanates has been developed. The cycloaddition provides a rapid entry to highly functionalized and enantioenriched bicyclic azocines. This reaction represents the first [4+2+2] cycloaddition strategy to construct nitrogen-containing eight-membered rings.