Asymmetric C-H insertion of Rh(II) stabilized carbenoids into acetals: A C-H activation protocol as a Claisen condensation equivalent

The dirhodium tetraprolinate, Rh-2(S-DOSP)(4) is an efficient catalyst in an enantio selective C-H activation protocol. Rh-2(S-DOSP)(4) catalyzed decomposition of aryldiazoacetates or vinyldiazoacetates results in the formation of transient rhodium carbenoid intermediates. These inter-mediates are capable of selectively inserting into the C-H bond of acetals. The resulting products are protected P-keto esters, and so the C-H activation protocol can be considered as strategically equivalent to the Claisen condensation. (c) 2005 Elsevier B.V. All rights reserved.