A highly efficient precatalytic system (XPhos-PdG2) for the Suzuki-Miyaura cross-coupling of 7-chloro-1H-pyrrolo[2,3-c]pyridine employing low catalyst loading.

Abstract

An expedient catalytic method for the synthesis of diverse 7-(hetero) aryl-1H-pyrrolo[2,3-c]pyridine analogues via microwave-assisted Suzuki-Miyaura cross-coupling reaction with excellent yield was developed. The method is found to be compatible with various boronic acids and potassium organotrifluoroborates. The formation of highly stable monoligated catalytic species is found to be instrumental in driving the reactions to excellent conversions in Suzuki-Miyaura coupling. Herein, we report our findings on the use of a highly efficient precatalytic system (XPhos-PdG2), containing a bulky monodentate biaryl ligand which allows the rapid reductive elimination to form the true monoligated Pd(0) catalytic species, thereby facilitating the Suzuki coupling reaction of 7-chloro, 6-azaindole system containing unprotected free N-H group with excellent conversions employing low catalyst loadings. Also, we observed that the use of near stoichiometric potassium organotrifluoroborate reagents as alternative coupling partners for boronic acids, which are prone to protodeboronation, resulted in excellent conversions.