Palladium‐Catalyzed Direct Diarylation of 2‐Benzyl‐1,2,3‐triazole: a Simple Access to 4‐Aryl‐ or 4,5‐Diaryl‐2‐benzyl‐1,2,3‐triazoles and Phenanthro[9,10‐d][1,2,3]triazoles

Abstract

AbstractThe reactivity of 2‐benzyl‐1,2,3‐triazole in palladium‐catalyzed direct arylation was studied. The reaction conditions for the selective synthesis of 2‐benzyl‐4‐aryl‐1,2,3‐triazoles in moderate to high yields using phosphine‐free Pd(OAc)2 catalyst and inexpensive KOAc base have been found. Then, from these 4‐aryl‐1,2,3‐triazoles, the palladium‐catalyzed C−H bond functionalization of the C5‐position allowed the synthesis of the corresponding 4,5‐diarylated 2‐benzyl‐1,2,3‐triazoles. This selective 4,5‐diarylation of 2‐benzyl‐1,2,3‐triazole was successfully applied for the straightforward building of the π‐extended polycyclic heteroaromatic structures phenanthro[9,10‐d][1,2,3]triazoles through Pd‐catalyzed C4‐ and C5‐intermolecular arylations followed by Pd‐catalyzed C−H intramolecular arylation.