Photoredox Catalyzed [3 + 2]-Annulation Reaction of Pyridinium 1,4-Zwitterionic Thiolates with Alkenes: Synthesis of Dihydrothiophenes

Abstract

Pyridinium 1,4-zwitterionic thiolates are usually used to develop ionic annulation reactions. However, radical reactions were rare. We developed a photoredox catalyzed [3 + 2]-annulation reaction of pyridinium 1,4-zwitterionic thiolates with alkenes, disclosed the new reactivity of pyridinium 1,4-zwitterionic thiolate, and provided a new synthetic method for dihydrothiophene.

A New Reaction Mode of 3-Halooxindoles: Acting as C–C–O Three-Atom Components for (3+3) Cycloaddition to Access Indolenine-Fused 2H-1,4-Oxathiines

“…Pyridinium 1,4-zwitterionic thiolates have emerged as a class of powerful and flexible reactants in cycloaddition reactions for accessing diversified heterocyclic compounds. , On the basis of our research interest in the synthesis of polyheterocyclic compounds, we envisioned that intermediate A would be attacked by the sulfur anion of pyridinium 1,4-zwitterionic thiolates, followed by either intramolecular N-attacking cyclization to access bridged [3,2,1] cyclic lactam compounds (Scheme c) or intramolecular O-attacking cyclization to access the fused polycyclic structure (Scheme d). To validate our proposal, we conducted density functional theory (DFT) analysis to confirm the possible priority of the N- or O-attacking pathway (see the Supporting Information for details).…”