Catalytic Oxysulfenylation of β,γ-Unsaturated Ketoximes: An Enantioselective Synthesis of Isoxazolines

We present a chiral Lewis base-catalyzed enantioselective oxysulfenylation strategy for the difunctionalization of β,γ-unsaturated oximes. High enantioselectivity was achieved through the introduction of phthalimide-derived benzylsulfenyl reagents, instead of traditional bulky or ortho-substituted thiophenol derivatives, with Lewis base catalysts in HFIP in the absence of an acid additive. The reaction demonstrates a wide substrate scope, and various sulfur-tethered isoxazolines were constructed with high yields and excellent enantiomeric ratios (up to 97:3 er) via the formation of C–O and C–S bonds.