Ultrasonic and microwave-assisted practical methods have been developed for the O-alkylation of aryl (β-naphthols) and Heteroaryl (hydroxy pyridines) in aqueous surfactant media in good to excellent yields. The developed methods are simple, efficient, economical and environmentally safe. Our novel methods describe a set of green methods to Williamson synthesis.

Thiamine hydrochloride (THC) is a biodegradable, readily available and inexpensive eco-friendly metal free biocatalyst, which is efficiently used in the condensation of 2-naphthol and aromatic aldehydes under thermal and microwave conditions without using toxic solvents. Developed methods herein afforded 14-aryl 14H-dibenzo [a, j] xanthenes in very good yields and offered several advantages such as shorter reaction time, comparable yield, neat practice, easy work-up and mild organo Lewis acid catalyst.