A Catalytic Approach to Intramolecular Wittig Reaction: Sulfonyl-Masked EDO Precursors Enabling Access to Heteroarenes

We report an efficient catalytic protocol for the intramolecular Wittig reaction enabled by the PIII/PV redox cycle, starting from Ts-containing electron-deficient olefin (EDO) precursors, leading to EDOs that are traditionally inaccessible. This reaction proceeds through a cascade sequence involving the in situ generated EDO from EDO precursor/phospha-Michael addition/O-acylation/intramolecular Wittig reaction. This strategy exhibits broad substrate scope, high chemoselectivity, and excellent functional group tolerance. The mechanistic investigations revealed that the EDO precursor undergoes an in situ Ts-elimination and addition process during the reaction.