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.