PCET-Enabled Photocatalytic and Electrosynthetic Ketyl Radical Cyclopropanation: Stereoselective Synthesis of Tetrahydronaphthalene-Fused Cyclopropa[1,2-b]furanones.

Tetrahydronaphthalene-2-yl acrylates are shown to undergo efficient ketyl radical cyclization-lactonization reactions leading to structurally elaborate tetrahydronaphthocyclopropa[1,2-b]furanones. The reductive ketyl radical cyclizations can be induced photocatalytically under mild and acid-free conditions in an amine/water buffer system as well as electrosynthetically, and the polycyclic strained γ-lactone products are generated with high stereoselectivity and yields.