A Convenient One‐Pot CuI‐Catalyzed Procedure for the Synthesis of S ‐( N ‐Heteroaryl) Thiocarboxylates From N ‐Heteroaryl Bromides and Thiobenzoic Acid

Aryl thiols constitute a crucial class of structural motifs and synthetic building blocks, while S-aryl thiocarboxylates represent an important class of latent aryl thiol precursors. CuI-catalyzed Ullmann-type cross coupling of aryl halides and thiobenzoic acid is a widely used synthetic method for S-aryl thiocarboxylates. Inspired by two individual methods reported earlier and associated drawbacks, a convenient one-pot two-step CuI-catalyzed procedure for the synthesis of S-(N-heteroaryl) thiocarboxylates from N-heteroaryl bromides and thiobenzoic acid was developed by combining of the two reaction systems and subsequent systematic optimization of the reaction conditions. This procedure employed CuI as a transition metal catalyst, a substoichiometric amount of NaI as iodide source and N,N'-dimethyl-1,2-ethanediamine and 1,10-phenanthroline as two ligands sequentially in each step. This one-pot procedure is highlighted by shorter reaction time, less iodide source and scalability compared to the two reported procedures while maintaining comparable overall isolated yields. Its utility was demonstrated by providing an alternative synthetic route to 25 and 26, two dual serotonin/dopamine receptor modulators, with fewer reaction steps and avoidance of harsh reaction conditions.