Cucurbit[6]uril supported β-Ni(OH)2 nanoparticles as a heterogeneous catalyst for the synthesis of quinazolines via acceptorless dehydrogenative coupling of alcohols with nitriles

Abstract

A new nanocomposite of β-Ni(OH)₂ nanoparticles immobilized on cucurbit[6]uril, β-Ni(OH)₂-CB[6], was designed and characterized using several physicochemical techniques, viz FTIR, PXRD, XPS, FESEM, HRTEM, EDAX, TGA, and ICP-OES. The nanocomposite was successfully applied as a heterogeneous catalyst in the synthesis of a series of pharmaceutically important quinazolines, in good to excellent yields (67–96%) and with high turnover numbers (TONs), via acceptorless dehydrogenative coupling (ADC) of alcohols with nitriles. To the best of our knowledge, this is the first report on the use of a heterogeneous catalyst in the ADC reaction between alcohols and nitriles to afford quinazolines. The catalyst could be reused up to four times with an insignificant decrease in its catalytic activity. The identity of all the isolated organic products were confirmed by ¹H and ¹³C{¹H} NMR studies. The striking features of the methodology are high atom economy, broad substrate scope and functional group tolerance, generation of non-toxic side-products, use of a cheap catalyst and stoichiometric reagents. The values of green chemistry matrices for the reaction were found to be in close proximity to the ideal values.