Undesirable deprotection of O-TBDMS groups by Pd/C-catalyzed hydrogenation and chemoselective hydrogenation using a Pd/C(en) catalyst

In general, O-TBDMS protective groups have been believed to be stable toward Pd/C-catalyzed hydrogenation conditions. In practice, however, frequent and unexpected loss of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. When a 10% Pd/C-ethylenediamine complex catalyst [10% Pd/C(en)] was used instead of 10% Pd/C, the undesirable problem was perfectly overcome and the chemoselective hydrogenation of reducible functionalities leaving intact the TBDMS protective group was achieved. (C) 2001 Elsevier Science Ltd. All rights reserved.