Halothiation as a Method for Oxidation of Primary Halides and Terminal Olefins to Aldehydes

The richly varied reactivity of the aldehyde group frequently imparts pivotal importance to this functionality in organic synthesis. This fact has resulted in the development of several methods for the elaboration of this structural unit from a variety of precursors.² The report delineates the feasibility of two new couplementary approaches which proceed under mild conditions and demonstrate the utility of “halothiation” as applied to the oxidation of primary halides and terminal olefins. We were led to investigate this approach as a direct consequence of our interest in the Ramberg-Bäcklund rearrangement³ where the preliminary step often involves α-chlorination of the sulfide substrate.⁴ Halothiation is defined by us as a three-step transformation involving introduction of an ArS moiety, directed α-chlorination of the resulting sulfide, and hydrolysis. In principle, of course, the ArSCH₂-unit is uniquely an aldehyde synthon and attention is therefore focused specifically on it at this time.