Palladium-catalyzed synthesis of ammonium sulfinates from aryl halides and a sulfur dioxide surrogate: a gas- and reductant-free process.

Sulfonyl-derived functional groups populate a broad range of useful molecules and materials, and despite a variety of preparative methods being available, processes which introduce the most basic sulfonyl building block, sulfur dioxide, using catalytic methods, are rare. Described herein is a simple reaction system consisting of the sulfur dioxide surrogate DABSO, triethylamine, and a palladium(0) catalyst for effective convertion of a broad range of aryl and heteroaryl halides into the corresponding ammonium sulfinates. Key features of this gas- and reductant-free reaction include the low loadings of palladium (1 mol%) and ligand (1.5 mol%) which can be employed, and the use of isopropyl alcohol as both a solvent and formal reductant. The ammonium sulfinate products are converted in situ into a variety of sulfonyl-containing functional groups, including sulfones, sulfonyl chlorides, and sulfonamides.