Total Syntheses of Variolin B and Deoxyvariolin B1

Two alternative synthetic routes have been developed for the preparation of variolin B and deoxyvariolin B. The strategy is based on the preparation of the core tricyclic ring common to all variolins, pyrido[3′,2′ :4,5]pyrrolo[1,2-c]pyrimidine, followed by a palladium-catalyzed cross-coupling reaction to give the tetracyclic system.