Copper‐Catalyzed Sulfenylation of Boronic Acids with Sulfonyl Hydrazides

An unprecedented sulfenylation reaction of carbon‐boron bonds has been developed using sulfonyl hydrazides as sulfenyl sources. A range of sulfonyl hydrazides underwent tetrakis(acetonitrile)copper(I) tetrafluoroborate [Cu(CH 3 CN) 4 BF 4 ]/2,2′‐bipyridine‐catalyzed sulfenylation with boronic acids under air to give structurally diverse thioethers in moderate to good yields. Preliminary mechanistic studies show that sulfonyl hydrazides are subjected to decomposition into thiosulfonates and disulfides followed by formation of carbon‐sulfur bonds with boronic acids. magnified image