six-step synthesis of the benzyl and allyl substituted bicyclic ketones 3a and 3b, which represent interesting building blocks for the synthesis of conformationally restricted receptor ligands. The key steps of the synthesis are the regioselective addition of ethyl acrylate to the piperazine 8, the sodium hexamethyldisilazide-induced Dieckmann cyclization of the diesters 10, and the decarboxylation of the