Intermolecular benzylic C–H functionalization using acceptor-acceptor metal-carbenes is currently understudied due to inherent issues in reactivity. Reported examples contain limited substrate scope and a lack of variation of the acceptor groups (e.g., α-diazomalonates), which constrains further derivatization and limits the potential usage of the C–H functionalization products. Herein, secondary N-aryl-α-diazo-β-amide esters are introduced as alternatives to α-diazomalonates for selective benzylic C–H functionalization. In the presence of a dirhodium catalyst, these diazo compounds reacted with various-substituted toluene derivatives to form α-alkylated products in up to 81% yield. Moreover, a series of selective derivatizations were accomplished under mild conditions to demonstrate the orthogonality of the ester and amide groups. These derivatizations include selective reductions, deoxygenations, decarboxylations, a-alkylations, and cross-coupling reactions. The broad substrate scope and selective derivatizations highlight the potential of the N-aryl-α-diazo-β-amide esters as an enabling technology for a variety of downstream synthesis.

N-aryl-α-diazo-β-amidoesters: A tool for intermolecular benzylic C(sp3)–H functionalization of methyl-substituted arenes and for further orthogonal carbonyl derivatizations

ACS Fall 2021

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