Tris(pentafluorophenyl)borane‐Catalyzed Carbenium Ion Generation and Autocatalytic Pyrazole Synthesis—A Computational and Experimental Study
Ayan Dasgupta, Rasool Babaahmadi, Sanjukta Pahar, Katarína Stefkova, Lukas Gierlichs, Brian F. Yates, Alireza Ariafard, Rebecca L. Melen
Abstract
Abstract In recent years, metal‐free organic synthesis using triarylboranes as catalysts has become a prevalent research area. Herein we report a comprehensive computational and experimental study for the highly selective synthesis of N‐substituted pyrazoles through the generation of carbenium species from the reaction between aryl esters and vinyl diazoacetates in the presence of catalytic tris(pentafluorophenyl)borane [B(C 6 F 5 ) 3 ]. DFT studies were undertaken to illuminate the reaction mechanism revealing that the in situ generation of a carbenium species acts as an autocatalyst to prompt the regiospecific formation of N‐substituted pyrazoles in good to excellent yields (up to 81 %).