Efficient synthetic routs for the direct and rapid construction of [5-6-6] ABC tricyclic systems of daphmanidin A-type and calyciphylline A-type alkaloids have been successfully developed. For the daphmanidin A-type, the synthesis of [5-6-6] tricyclic framework utilize a HCl-mediated intramolecular Aldol reaction to construct the bicyclo[2.2.2]octane core and a thermal condensation to afford the ABC ring system. In addition, for the calyciphylline A-type, an improved synthesis of ABC [5-6-6] tricyclic system was developed, featuring an introduction of methyl ester group at C2 before the Pd-catalyzed intramolecular oxidative alkylation to construct the desired bowl-shape tricyclic core with stereochemical control. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.