A first biogenetic-type asymmetric synthesis of natural (+)-maritidine from L-tyrosine is described. Phenolic oxidative coupline of monophenol (10b) with thallium (III) trifluoroacetate afforded the corresponding spiro dienone (11b) in 66.5% yield. Asymmetric cyclization of dienone (14) was found to occur highly selectively to give one diastereomer (15) preferentially. Removal of the carboxamide group in 15 was effected by reductive decyanization of the intermediate amino nitrile (18) by sodium in liquid ammonia to (+)-epimaritidine (19), which was epimerized to the objective (+)-maritidine by the known method.