Syntheses of aza-analogous iso-ergoline scaffolds using carbene mediated C–H insertion

A novel direct, flexible, and robust approach to the iso-ergoline tetracyclic system in which a five or six-membered ring is established by intramolecular carbene C–H insertion is reported. The protocol involves a two step conversion of an aromatic aldehyde to the corresponding hydrazone and without purification further conversion to the diazo-compound followed by thermal carbene formation and C–H insertion α to a nitrogen.