Photochemical Radical Ring-Opening Alkylation of Cyclopropanols with Katritzky Salts

Ring-cleavage reactions of cyclopropanols are a valuable tool for the synthesis of linear and α- or β- branched ketones. Here, we describe a visible light induced ring-opening alkylation of these substrates with benzyl, allyl and secondary alkyl Katritzky salts. The reaction proceeds under dual photoredox and nickel catalysis in the presence of titanium(IV) isopropox-ide additive. Mechanistically, the ring opening step starts with generation of cyclopropyloxy radical and follows by its isomerization to β-carbonyl radical. This enables regioselective preparation of β-branched ketones from 1,2-disubstituted hy-droxycyclopropanes