Synthesis of Benzothiazoles through Copper‐Catalyzed One‐Pot Three‐Component Reactions with Use of Sodium Hydrosulfide as a Sulfur Surrogate

Copper‐catalyzed one‐pot three‐component reactions of 2‐iodoanilines, aldehydes, and NaSH · n  H 2 O afford benzothiazoles in good yields. When CuCl was employed as a catalyst in the absence of a ligand, a variety of aromatic aldehydes and substituted 2‐iodoanilines reacted with NaSH · n  H 2 O to produce the corresponding 2‐arylbenzothiazoles in 70–98 % yields. The copper catalyst plays a key role in C–S bond formation between NaSH · n  H 2 O and the aryl iodide that was formed from the condensation of 2‐iodoaniline and aldehyde. It was found that NaSH · n  H 2 O functions as a sulfur surrogate and oxidant in the formation of benzothiazole.