Friedel-Crafts acylation of 2-trimethylsilylnorbornene. Effect of acyl group on the position of attack

Article abstract of DOI:10.1016/S0040-4020(99)00402-0

The acylation of 2-trimethylsilylnorbornene 1 in the presence of aluminium chloride gives minor quantities of the expected 2-norbornenyl ketones 4. The formation of 3 and 5 as major products indicates that either α- or β-attack takes place predominantly depending on the nature of the acyl group, and the β-silicon effect is not a decisive factor. The β-silyl cation intermediate 2 mainly leads to nortricyclyl ketones 3 through 1,3- deprotonation, and the α-silyl cation 8 undergoes rearrangement to give novel bridge-head silylated products 5.