Rhodium-Catalyzed Asymmetric Cyclopropanation via Azavinyl Carbenoids

Significance

The authors previously reported that 1-sulfonyl 4-substituted 1,2,3-triazoles could serve as stable synthetic equivalents of diazo compounds (V. V. Fokin and co-workers J. Am. Chem. Soc. 2008, 130, 14972). In the present report they describe a procedure for the in situ generation of azavinyl rhodium carbenoids from NH-triazoles and demonstrate their utility in asymmetric cyclopropanation. This methodolgy avoids the use of potentially hazardous reagents. It is noteworthy that the method formally provides products arising from carbenoids with an α-aldehyde functionality.