Synthesis of a Class of I(III)/S(VI) Reagents and Their Reactivity in Photochemical Cycloaddition Reactions with Unsaturated Bonds

Abstract We describe the synthesis of a new class of hypervalent iodine reagents with a transferrable sulfoxonium group. The solid-state structure of representative compounds was characterized as a mixed iodonium-sulfoxonium ylide by X-ray diffraction analysis. These well-defined reagents were examined in visible-light-promoted cyclization reactions with versatile unsaturated bonds including alkenes, alkynes, nitriles and allenes. Two distinct cyclization pathways were identified, which were controlled by the substituent of the unsaturated bond. The cycloaddition protocol featured simple operation, mild reaction conditions, and excellent functional group tolerance, affording a broad range of sulfoxonium-containing cyclic structures in moderate to excellent yields. Furthermore, the sufoxonium group in the product would be transformed into diverse functional groups and structural motifs via single electron transfer and transition-metal catalysis.