Copper(I)-catalyzed cascade synthesis of 2-arylsulfanyl- arylcyanamides

Abstract

We have developed a ligand‐assisted copper(I)‐catalyzed two sequential heteroarylation sequence. An intramolecular S‐arylation is followed by an intermolecular N‐arylation leading to the direct synthesis of N‐aryl‐2‐aminobenzothiazoles. In most cases however, the 2‐arylsulfanyl‐arylcyanamide was the major product obtained via an intramolecular C-S bond formation, associated with C-S bond breakage, followed by an intermolecular S‐arylation. The selectivity of this ligand‐assisted reaction is quite different as compared to that of ligand‐free reactions and the rates are much faster giving good yields of products. Various cyanamides can be prepared in excellent yields from their corresponding 1‐substituted thioureas with or without the assistance of a ligand with a catalytic quantity of copper(I).