Decarboxylative Alkylation of Unactivated Olefins via Photoinduced Fe-LMCT: Access to Alkylated Dihydropyrazoles/Tetrahydropyridazines

Abstract

Herein, we disclose a photoinduced FeCl3-mediated ligand-to-metal charge transfer (LMCT) approach for the decarboxylative alkylation/cyclization of N-allyl and N-homoallyl aldehyde hydrazones. Readily available tertiary and challenging secondary aliphatic carboxylic acids serve as alkyl radical precursors, enabling functionalization of unactivated olefins to furnish alkylated dihydropyrazoles and tetrahydropyridazines in good to excellent yields under mild, oxidant-free conditions, without requiring precious-metal photocatalysts. The protocol exhibits broad substrate scope and functional group tolerance, including late-stage diversification of bioactive molecules and drug-derived acids.