TBAI-Mediated Cyclization and Methylsulfonylation of Propargylic Amides with Dimethyl Sulfite.

A tetramethylammonium iodide (TBAI)-mediated cyclization and methylsulfonylation of propargylic amides enabled by dimethyl sulfite as a SO2 surrogate and methyl source have been developed. The transition metal-free and oxidant-free reaction provides a practical and efficient approach for the selective synthesis of methylsulfonyl oxazoles in moderate to excellent yields with good functional group compatibility.