SbCl5–wet acetonitrile: a new system for chemoselective O-desilylation

A new efficient method for deprotection of TBDMS derivatives of phenols, primary alcohols, carboxylic acids and secondary amines, consisting of SbCl5 and MeCN with 0.1% water (w/v), is reported. It effects inter alia desilylation of a CH2OTBDMS group in the presence of a ketal function. © 2003 Elsevier Ltd. All rights reserved. The application of silyl groups as protecting groups for O, N, S, etc., in synthesis is well known. Since its introduction to organic chemistry by Corey, one such group namely, the t-butyldimethylsilyl group (TBDMS) has occupied a privileged position. Its popularity, especially with respect to O-protection, is undoubtedly due to its enhanced stability in basic and mildly acidic conditions, compared with other common silicon-based analogues, and the mildness of conditions under which it can be removed. In connection with our current studies on the synthesis of heterocyclic compounds, an attempted desilylation of substance 1, and other structurally related compounds, with a variety of F ion sources in THF led to intractable mixtures. However, a solution of 1 in wet acetonitrile, 0.1% water (w/v), on treatment with a sub-stoichiometric quantity of SbCl5 (0.1 equiv.) cleanly afforded the nitrone 1a in good yield (Eq. (1)).