Carbene Transfer and Carbene Insertion Reactions Catalyzed by a Mixed-Ligand Copper(I) Complex

The catalytic activity of the mixed-ligand copper(I) complex [Cu(PPh3)2(κ2-O,O"-lact)] (1) {lact = L-(+)-lactate} has been investigated in carbene transfer and carbene insertion reactions. Complex 1 catalytically promoted the diastereoselective cyclopropanation of olefins in the presence of ethyl diazoacetate (EDA), under mild conditions, and with a low catalyst loading (1 mol-%). In the case of internal alkenes, a trans/cis ratio of up to 93:7 was reached. Moreover, compound 1 easily promoted the insertion of the carbene fragment deriving from the decomposition of ethyl diazoacetate into O–H (alcohols and phenols) and N–H (amine) bonds, with formation of the corresponding ethyl 2-alkoxyacetate, ethyl 2-phenoxyacetate, and ethyl 2-aminoacetate derivatives in good to high yields.