Synthesis 2007(2): 299-303  
DOI: 10.1055/s-2006-958948
PAPER
© Georg Thieme Verlag Stuttgart · New York

Perchloric Acid Adsorbed on Silica Gel (HClO4-SiO2) as an Inexpensive, Extremely Efficient, and Reusable Dual Catalyst System for Acetal/Ketal Formation and Their Deprotection to Aldehydes/Ketones

Raj Kumar, Dinesh Kumar, Asit K. Chakraborti*
National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar, Punjab 160062, India
Fax: +91(172)2214692; e-Mail: akchakraborti@niper.ac.in;
Further Information

Publication History

Received 6 October 2006
Publication Date:
14 December 2006 (online)

Abstract

Perchloric acid adsorbed on silica gel (HClO4-SiO2) is reported as extremely efficient, inexpensive, and reusable catalyst for dual role for protection of aldehydes/ketones (with trialkyl orthoformates) as acetals/ketals and deprotection (with water-alcohol­) to regenerate the carbonyl compounds in high yields at room temperature and in short times. Acetalization/ketalization of electrophilic aldehydes/ketones was carried out under solvent-free conditions. Weakly electrophilic aldehydes/ketones and aldehydes having a substituent that can coordinate with the catalyst, required the corresponding alcohol as solvent.