Redox-Neutral Access to Sultams from 2-Nitrochalcones and Sulfur with Complete Atom Economy

A catalyst-free, redox-neutral, and completely atom-economical synthesis of sultams by simply heating 2-nitrochalcones with elemental sulfur in 3-picoline or N-methylmorpholine is described. The S–N, C–S, and S═O bonds of the sulfonamide are efficiently formed between the nitrogen atom of the 2-nitro group and the α-carbon of the chalcones and elemental sulfur with the migration of two oxygen atoms from the 2-nitro group to the sulfur atom.