Total Synthesis Of Dimeric Alkaloids Chimonanthine, Folicanthine And Several 2,7’-Cyclolignans

This thesis described research results about the total syntheses of some natural products. It is mainly divided into two parts, and the first part includes Chapter One and Chapter Two. Chapter One summarized diverse synthesis strategies of dimeric hexahydropyrrolo[2,3-b]indole alkaloids represented by Chimonanthine and Folicanthine. Chapter Two discussed the homocoupling of alkyl bromide at room temperature catalyzed by Ni(0)·Ln developed by our group, and its application in the total synthesis of Chimonanthine and Folicanthine.The second part (Chapter Three) described collective synthesis of several 2,7’-cyclolignans and their correlations by chemical transformation. First, efficient synthesis (only 7 steps with 25% overall yield) of (±)-sacidumlignan A with a naphthalene skeleton has been successfully achieved, where acid triggered tandem reaction starting from Ueno-Stork cyclization product played an important role. Moreover, potentially biomimetic conversion from (±)-sacidumlignan D to sacidumlignan A could be realized.Next, collective synthesis of anti-malarial 2,7’-cyclolignans has been stereoselectively achieved employing (±)-cyclogalgravin as a linchpin through a series of functional group conversions including redox reactions. Interestingly, (±)-cyclogalgravin can be correlated with (±)-kadangustin J albeit isolated from different plant source, through the highly efficient dehydrative cyclization reaction with excellent diastereotopic veratryl group differentiation and concomitant construction of the C(1)-C(7) bond. It is noteworthy that the first synthesis of stereodivergent (±)-8,8’-epi-aristoligone, (±)-8’-epi-aristoligone and (±)-8’-epi-8-OH-aristoligone was demonstrated, respectively.