Maleimide-Dependent Rh(III)-Catalyzed Site-Selective Mono and Dual C-H Functionalization of 2-Arylbenzo[]thiazole and Oxazole Derivatives.

The site-selective functionalization of aromatic compounds via C-H activation has emerged as a popular tool in organic synthesis. In this study, we report a regioselective coupling of maleimide to 2-arylbenzo[]thiazoles in the presence of a rhodium(III) catalyst. Depending upon the nature of the substituent (-group) present in the maleimide substrate, either mono- or bis-1,4-addition products were observed in this methodology. In the case of = aryl, cyclohexyl, and -butyl, mono coupling was observed, whereas substituents, such as methyl, ethyl, benzyl, and methyl thiophene, provided bis coupling as the major products. Similar selectivity was also observed in the case of 2-arylbenzo[]oxazoles.