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, Email: akchakrabortiniper.ac.in
R. Kumar, D. Kumar, A. K. Chakraborti, Synthesis, 2007, 299-303.
Perchloric acid adsorbed on silica gel is an extremely efficient, inexpensive, and reusable catalyst for the protection of aldehydes and ketones and the subsequent deprotection. Acetalization was mostly carried out under solvent-free conditions with trialkyl orthoformates, but weakly electrophilic carbonyl compounds and substrates that can coordinate with the catalyst, required the corresponding alcohol as solvent.
see article for more examples
S. Rudrawar, R. C. Besra, A. K. Chakraborti, Synthesis, 2006, 2767-2771.