Maleimide-Dependent Rh(III)-Catalyzed Site-Selective Mono and Dual C–H Functionalization of 2-Arylbenzo[<i>d</i>]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[<i>d</i>]thiazoles in the presence of a rhodium(III) catalyst. Depending upon the nature of the substituent (<i>R</i>²-group) present in the maleimide substrate, either mono- or bis-1,4-addition products were observed in this methodology. In the case of <i>R</i>² = aryl, cyclohexyl, and <i>tert</i>-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[<i>d</i>]oxazoles.