Total synthesis of (+/-)-pallavicinin and (+/-)-neopallavicinin

Two novel diterpenes, named pallavicinin (1)and neopallavicinin (2)were first isolated from liverwort Pallavicinia subciliata by Wu16 and their coworkers in 1994. These compounds show potential bioactivities, such as antipyretic properties, muscle regeneration and detoxification.17,18 The diverse structural features of these novel diterpenes in conjunction with their potential bioactivities have stimulated our considerable interest in the quest for their total synthesis.; In Chapter 1, an overview of the isolation, structure elucidation and bioactivities of pallavicinin (1) and neopallavicinin ( 2) are presented. In addition, various synthetic approaches toward the analogous skeletons of the two novel diterpenes are reviewed.; Chapter 2 is concerned with the aim of our research work, retrosynthetic analysis and strategy. Herein, we report the synthesis of the pivotal precursor aldehyde (112) by a Grob fragmentation procedure. In addition, model studies of the key biomimetic aldol cyclization are also discussed. We completed the total synthesis of the two novel diterpenes (+/-)-( 1) and (+/-)-(2) via intramolecular Michael reaction and alpha-ethylidenation starting from (+/-)-Wieland-Miescher ketone.; In Chapter 3, a brief conclusion is provided.*; *Please refer to dissertation for diagrams.