540731-58-6Relevant articles and documents
General approach for the synthesis of sarpagine indole alkaloids. Enantiospecific total synthesis of (+)-vellosimine, (+)-normacusine B, (-)-alkaloid Q3, (-)-panarine, (+)-Na-methylvellosimine, and (+)-Na-methyl-16-epipericyclivine
Yu, Jianming,Wang, Tao,Liu, Xiaoxiang,Deschamps, Jeffrey,Flippen-Anderson, Judith,Liao, Xuebin,Cook, James M.
, p. 7565 - 7581 (2003)
The first total synthesis of (+)-Na-methyl-16-epipericyclivine (9) was completed [from D-(+)-tryptophan methyl ester] in an overall yield of 42% (eight reaction vessels). The optical rotation [[α]D +22.8 (c 0.50, CHCl3)] obtained on this material confirmed that the reported optical rotation [[α]D 0 (c 0.50, CHCl 3)]47 was biogenetically unreasonable. The total syntheses of (+)-vellosimine, (+)-normacusine B, (-)-alkaloid Q3, (-)-panarine, and (+)-Na-methylvellosimine are also described. Moreover, a mixed sample (1:1) of synthetic (-)-panarine and natural (-)-panarine yielded only one set of signals in the 13C NMR; this indicated that the two compounds are identical and further confirmed the correct configuration of (+)-vellosimine, (+)-normacusine B, and (-)-alkaloid Q3. In this approach, the key templates, (-)-Na-H,N b-benzyltetracyclic ketone 15a and (-)-Na-methyl,N b-benzyltetracyclic ketone 43 were synthesized on multihundred gram scale by the asymmetric Pictet-Spengler reaction and a stereocontrolled Dieckmann cyclization via improved sequences. An intramolecular palladium (enolate-mediated) coupling reaction was employed to introduce the C(19)-C(20) E-ethylidene function in the sarpagine alkaloids for the first time in stereospecific fashion.
