Synthetic route to ergot alkaloids

Abstract

Rye is sometimes infected by a fungus called Claviceps purpurea. The term ergot designates the dark, brown, tuberous bodies which can be collected before or during harvesting and represent one of the most remarkable drugs of our therapeutic arsenal. Actually, the most significant alkaloids are metabolic products of these fungi. We elaborated three alternative total synthetic pathways to construct the ergoline skeleton, one of which - suitable for scaling up - finally resulted in (+)-lysergic acid (32a) and a-ergocryptine (1) (Schemes 5 and 6). © 2005 Verlag Helvetica Chimica Acta AG.