ChemInform Abstract: Cyclohexadienone Annulations of Aryl Carbene Complexes of Chromium: New Strategies for the Synthesis of Indole Alkaloids.

ChemInform Abstract

Reaction of the pentacarbonylchromium carbene complexes (I) and (VI) with the alkynes (II) and subsequent oxidation give the quinones (III) and (VII). Analogous reaction of the carbene complexes (IV) and (VIII) yields the cyclohexadienones (V) and (IX) after oxidation. A new approach to the synthesis of aspidosperma alkaloids such as vindoline (XIII) is the reaction of the carbene complex (X) with the alkyne (XI), leading to the formation of the polycyclic compound (XII).