SYNTHESIS OF CYCLOHEXENYLAMINES BY RING CLOSING METATHESIS

Starting from 5-pentenaldehyde 1, the 1-allyl-4-pentenylamines 2a-d we re prepared. The ring closing metathesis reaction of these dienes usin g the Grubbs catalyst 3 gave the corresponding cyclohexenylamines 4a,b and 48 in high yield. The secondary amine 2c was recovered unchanged. This route to compound 48 represents a formal total synthesis of the alkaloid epibatidine. In addition, 4b was transformed by electrophilic transannular cyclization to the bicyclic urethanes 5a and 5b.