Rhodium(II)- and Copper(II)-Catalyzed Reactions of Enol Diazoacetates with Nitrones: Metal Carbene versus Lewis Acid Directed Pathways
作者:Yu Qian、Xinfang Xu、Xiaochen Wang、Peter J. Zavalij、Wenhao Hu、Michael P. Doyle
DOI:10.1002/anie.201202525
日期:2012.6.11
A complimentary cat.: Copper(II) hexafluoroantimonate catalyzes the formal [3+3] cycloaddition of Lewisacid activated nitrones and vinyl diazoacetates to produce 3,6‐dihydro‐1,2‐oxazines in yields of up to 96 % and diastereoselectivities greater than 25:1 (see scheme). This process compliments the metalcarbenepathway that is catalyzed by rhodium(II) species.
An efficient, copper-catalyzed [3+1+1] cycloaddition reaction was developed for the expedient synthesis of pharmacologically interesting polysubstituted pyrroles from easily available nitrones and α-acidic isocyanides. The given approach features a new mode of cycloaddition between nitrones and isocyanides with wide substrate scope, good functional group tolerance, and operational simplicity. The operando