Sulfonyl Azides as Precursors in Ligand-Free Palladium-Catalyzed Synthesis of Sulfonyl Carbamates and Sulfonyl Ureas and Synthesis of Sulfonamides
作者:Shiao Y. Chow、Marc Y. Stevens、Luke R. Odell
DOI:10.1021/acs.joc.5b02755
日期:2016.4.1
An efficientsynthesis of sulfonyl carbamates and sulfonyl ureasfrom sulfonyl azides employing a palladium-catalyzed carbonylation protocol has been developed. Using a two-chamber system, sulfonyl azides, PdCl2, and CO gas, released ex situ from Mo(CO)6, were assembled to generate sulfonyl isocyanates in situ, and alcohols and aryl amines were exploited as nucleophiles to afford a broad range of sulfonyl
Successful conditions for the transcarbamylation/transesterification reaction of sulfonylcarbamates with alcohols by microwave heating under continuous flow conditions were developed. After optimization of the processes, two series of O-alkylsulfonylcarbamates were obtained in high yields and purities using microwave transparent borosilicate tube reactors. In order to also illustrate the usefulness of the protocol in a medicinal chemistry context, the methodology was used for the synthesis of three angiotensin II type 2 receptor ligands.