Alkyl sulfonyl fluorides as ambiphiles in the stereoselective palladium(II)-catalysed cyclopropanation of unactivated alkenes

Here we present the ambiphilic reactivity of alkyl sulfonyl fluorides in the stereoselective synthesis of diverse cyclopropanes from olefins, under palladium(II) catalysis. The sulfonyl fluoride functionality serves as both an acidifying group and an internal oxidant within the ambiphile, enabling successive carbopalladation and oxidative addition steps in the catalytic cycle, respectively. The transformation grants access to cis-substituted cyclopropanes and exhibits broad compatibility with various alkyl sulfonyl fluorides, including those bearing -CN, -CO₂R, isoxazolyl, pyrazolyl and aryl groups. With internal alkene substrates, 1,2,3-trisubstituted cyclopropanes that are otherwise challenging to synthesize are formed in good-to-moderate yields and predictable diastereoselectivity. Detailed mechanistic insights from reaction progress kinetic analysis and density functional theory calculations reveal that the S_N2-type C-SO₂F oxidative addition is the turnover-limiting and diastereoselectivity-determining step.