Résumé/Abstract Several 2-alkyl-1-phenoxycarbonyl-Δ 3-piperidines were prepared by the addition of alkylzinc iodides to dihydropyridinium salt (9). The treatment of 4-hydroxy-2- methyl-1-phenoxycarbonyl-1, 2, 3, 4-tetrahydro-pyridine (12) with allyltrimethylsilane in the presence of a variety of Lewis acids was studied and found to give cis-and trans-2-6-dialkyl- Δ 3-piperidines (14) and (15) in moderate to good yield. Among the Lewis acids studied, ...