Aryl versus Alkyl Redox-Active Diazoacetates  Light-Induced C-H Insertion or 1,2-Rearrangement

Diazo compounds with redox-active leaving groups areversatilereagents for orthogonal functionalizations, previously utilized inthe Rh-catalyzed synthesis of highly substituted cyclopropanes. Photochemicalactivation of aryl-substituted diazoacetates generates carbenes, whereasredox-active esters can furnish C-radicals via the photoexcitationof EDA complexes. However, the photochemical behavior of these twofunctionalities, while present in one molecule, remains to be defined.We demonstrate that under light irradiation, reactions occur onlyon the diazo moiety, leaving the NHPI functionality intact. Not onlyaryl- but also alkyl-substituted NHPI diazoacetates are activatedby blue light; either C-H insertion or the hydrogen/carbon1,2-rearrangement occurs depending on the aryl/alkyl group.