Selective palladium-catalyzed amination of the heterocyclic core of variolins

A new and selective palladium-catalyzed amination of the pyrido[3′,3′:4,5]pyrrolo[1,2-c]pyrimidine nucleus, the heterocyclic core of the variolin alkaloids, is described. The method allows the introduction of amino and aryl- and alkylamino substituents on the C9 position in advanced precursors of variolin B and deoxyvariolin.We acknowledge financial support from the Spanish Ministerio de Educación y Ciencia (project CTQ2005/011060), Comunidad de Madrid (CAM) and Universidad de Alcalá (UAH) (project CAM/UAH-2005/044) and a grant (A.B.) from the Ministerio de Educación y Ciencia