The synthesis of p-acetyl and p-benzoyl derivatives of various benzylsilanes (p-(RCO)-C-1-C6H4-(CRR3)-R-2-SiMe3: R-1, R-2, R-3=Me, H, H; Me, H, Ph; Me, H, Me; Me, Me, Me; Ph, H, H; Ph, H, Ph; Ph, H, Me; Ph, Me, Me), xanthenes (3-benzoyl and 3,6-dibenzoyl), and 9-Me3Si-xanthenes (3-benzoyl, 3,6-dibenzoyl, 3-acetyl and 3,6-diacetyl) using Friedel-Crafts reactions and typical Lewis acid catalysts (AlCl3, FeCl3, ZnCl2) is described. Desilylation side reactions caused by AlCl3 become significant in substrates with weak carbon-silicon bonds (e.g. Ph2CH-SiMe3), and in the case of Ph3C-SiMe3 only the desilylation product Ph3CH was isolated. (C) 2002 Elsevier Science Ltd. All rights reserved.
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