Studies toward Labeling Cytisine with [<sup>11</sup>C]Phosgene: Rapid Synthesis of a δ-Lactam Involving a New Chemoselective Lithiation−Annulation Method
receptors, with [11C]phosgene, the rapid synthesis of a lactam model of our target has been studied. The key step of the δ-lactam formation is a new chemoselective lithiation−annulation method, under high dilution, of a suitable piperidinylcarbamoyl chloride. This precursor was obtained from (2-hydroxyethyl)piperidine in a linear synthetic sequence involving a Corey−Fuchs olefination of the corresponding