Radical Ring-Opening Fluorosulfonylation of Methylenecyclobutanols via Electron Donor-Acceptor Photoactivation.

A visible-light-mediated catalyst- and additive-free method for radical ring-opening fluorosulfonylation of methylenecyclobutanols is reported. Sulfuryl chlorofluoride acts as a FSO 2 radical precursor as well as an electron acceptor to form electron donor-acceptor complexes with various methylenecyclobutanol substrates. This method shows fully regioselective and ( E )-stereoselective ring-opening processes, providing a variety of FSO 2 -functionalized γ,δ-unsaturated carbonyls in 38-77% yields. A selection of product diversifications has been studied to demonstrate the versatility of these sulfonyl fluoride products.