Synthesis of the ABC Tricyclic System of Daphnicyclidin A.

A substrate-stereocontrolled synthesis of the ABC tricyclic system of daphnicyclidin A is developed. The key reactions include an efficient tandem N-allylation-SN2' reaction to assemble 2,3,4-cis trisubstituent pyrrolidine ring C and two intramolecular Horner-Wadsworth-Emmons reactions to construct cycloheptanone ring A and piperidine ring B.

[Studies on the synthesis and antitumor activity of the derivatives of cephalotaxine alkaloid esters].

AIM: To design and synthesize some cephalotaxine and drupacine derivatives with different substituentes on C3'-N of taxol side chain. METHODS: Protective side chain acid VI (4'S,5'R) was prepared from optically active (2'R,3'S) methyl beta-phenyl glycidate I in five steps. The desired acids were coupled with cephlotaxine and drupacine respectively in the presence of 2-DPC/DMAP, followed by acidic hydrolysis and acylating to give novel alkloid esters with different substitutes on C3'-N. RESULTS: The seven new esters were studied for antitumor activity, the results showed that the antitumor activity was influenced by the substituentes on C3'-N. CONCLUSION: It might provide some rational basis for further structral modification.