Novel oxidative coupling of 2-naphthols to 1,1′-bi-2-naphthols catalysed by solid Lewis acids using atmospheric oxygen as oxidant
Abstract
The oxidative coupling of 2-naphthol (1a) and 6-bromo-2-naphthol (1b) to 1,1′-binaphthol (2a) and 6,6′-dibromo-1,1′-binaphthol (2b), respectively, have been carried out rapidly and in excellent yield by employing a series of solid Lewis acids, FeCl3/Al2O3, FeCl3/SiO2 and Fe3+ exchanged montmorillonite, as catalysts and aerial oxygen as oxidant.