Demonstration of 14–20-membered intramolecular carbonyl ylides: diastereoselective synthesis of macrocycles incorporating spiro-indolooxiranes

A range of macrocycles (13–19-membered) possessing spiro-indolooxirane unit were synthesized with complete diastereoselectivity in good yield by the rhodium(II) acetate catalyzed reaction of substituted cyclic diazoamides in dry dichloromethane. The reaction proceeds via the formation of the corresponding macrocyclic carbonyl ylide followed by a con-rotatory electrocyclization process.