Base-Promoted Synthesis of S‑Arylisothiazolones via Intramolecular Dehydrative Cyclization of α‑Keto‑N‑acylsulfoximines

A base (Et₃N)-promoted synthesis of 1,4-diarylisothiazolones from α-keto-N-acylsulfoximines has been achieved. The reaction proceeds via α-hydrogen abstraction from sulfoximine, followed by an intramolecular nucleophilic attack at the keto carbonyl to form a tert-hydroxy isothiazolone intermediate. The 1,4-substituted isothiazolone is obtained after dehydration via an E1cB path. This one-pot synthesis of isothiazolinones has a broad substrate scope, has a high atom economy, and provides products with good yields. The ΔE_LUMO–HOMO is calculated using Gaussian 16 at the B3LYP/6-31G(d,p) level of theory.