Bismuth compounds in organic synthesis: Bismuth triflate-catalyzed intramolecular carbonyl ene reaction

ORGN 119

Ram S. Mohan, rmohan@iwu.edu1, Ann C. Palma2, Mai P. Nguyen2, and Erin D. Anderson2. (1) Laboratory for Environmentally Friendly Organic Synthesis, Department of Chemistry, Illinois Wesleyan University, 201 East Beecher Street, Bloomington, IL 61701, (2) Laboratory for Environment Friendly Organic Synthesis, Department of Chemistry, Illinois Wesleyan University, 201 East Beecher Street, Bloomington, IL 61701
The intramolecular Ene Reaction is a useful method for forming CóC bonds. Bismuth triflate (0.1 to 1 mol %) is a highly efficient catalyst for the cyclization of citronellal, 1. The cyclization yields isopulegol 2 and its diastereomer 3. The effect of solvents and other catalysts on this cyclization have been investigated and will be discussed. The bismuth triflate catalyzed carbonyl ene reaction has also been extended to the synthesis of piperidine rings. Bismuth compounds are attractive because of their remarkably low toxicity, low cost and ease of handling.