Enantioselective Benzylic C–H Insertions with Diazosuccinate Esters

The first enantioselective benzylic C–H insertion using α-alkyl-α-diazoesters, facilitated by a well-established chiral dirhodium(II) catalyst, is presented. This reaction selectively functionalizes primary benzylic C–H bonds with good to excellent enantioselectivity (up to 95% ee), thereby demonstrating the synthetic utility of this previously underexplored class of diazo reagents. The resulting differentiated diester products undergo selective monoester removal, thereby enabling subsequent functional-group manipulation of the liberated carboxylic acid and expanding access to enantioenriched building blocks.