Phenol oxidation and biosynthesis. Part XIV. (Alkaloids from Croton species. Part VII.) The biosynthesis of crotonosine

Abstract

The incorporation of (±)-, (+)-, and (–)-coclaurino into crotonosine in Croton linearis Jacq. has been investigated and the specific utilisation of the (+)-isomer demonstrated. The isomeric (±)-isococlaurine is not a precursor of crotonosine although (±)-norcoclaurine is incorporated. The evidence supports the oxidative cyclisation of (+)-coclaurine to a dienone. Double labelling experiments involving the methoxy-group of (±)-coclaurine showed that most, but not all, of the methoxy-activity was lost in conversion into crotonosine; the significance of these results is discussed.