structure of the amide sidechain of psymberin, a potent and selective cytotoxin, is proposed. Syn and anti models of the amide sidechain were prepared, and the structural assignment was confirmed by X-ray crystallographic analysis of the anti isomer. Comparison of (1)H and (13)C NMR data establishes homology between the natural product and the synthetic model compound of anti configuration and not the corresponding
Studies toward the Unique Pederin Family Member Psymberin: Full Structure Elucidation, Two Alternative Total Syntheses, and Analogs
作者:Yu Feng、Xin Jiang、Jef K. De Brabander
DOI:10.1021/ja3057612
日期:2012.10.17
Two synthetic approaches to psymberin have been accomplished. A highly convergent first generation synthesis led to the complete stereochemical assignment and demonstrated that psymberin and irciniastatin A are identical compounds. This synthesis featured a diastereoselective aldol coupling between the aryl fragment and a central tetrahydropyran core and a novel one-pot procedure to convert an amide, via intermediacy of a sensitive methyl imidate, to the N-acyl aminal reminiscent of psymberin. The highlights of the second generation synthesis include an efficient iridium-catalyzed enantioselective bisallylation of neopentyl glycol and a stepwise Sonogashira coupling/cycloisomerization/reduction sequence to construct the dihydroisocoumarin unit. The two synthetic avenues were achieved in 17-18 steps (longest linear sequence, similar to 14-15 isolations) from 3 fragments prepared in 7-8 (first generation) and 3-8 (second generation) steps each. This convergent approach allowed for the preparation of sufficient amounts of psymberin (similar to 0.5 g) for follow-up biological studies. Meanwhile, our highly flexible strategy enabled the design and synthesis of multiple analogs, including a psymberin pederin hybrid, termed psympederin, that proved crucial to a comprehensive understanding of the chemical biology of psymberin and related compounds that will be described in a subsequent manuscript.
Synthesis and Complete Stereochemical Assignment of Psymberin/Irciniastatin A
作者:Xin Jiang、Jorge García-Fortanet、Jef K. De Brabander
DOI:10.1021/ja0537068
日期:2005.8.1
We describe a concise and flexible synthetic avenue for the preparation of compounds with structures relevant to those proposed for the novel marine-derived differential cytotoxins psymberin and irciniastatin A. Our efforts led to their complete stereochemical assignment and the notion that psymberin and irciniastatin A are identical compounds. Our total synthesis features an interesting termini-differentiating
我们描述了一种简洁灵活的合成途径,用于制备结构与新型海洋衍生差异细胞毒素 psymberin 和 irciniastatin A 相关的化合物。我们的努力导致了它们的完整立体化学分配以及 psymberin 和 irciniastatin A 相同的概念化合物。我们的全合成具有从 C2 对称双烯烃前体获得的二醛的有趣的末端差异化乳醇化、差向异构腈的温和铂催化水解、制备灵敏的亚胺酸甲酯的新方案和一锅法转化这些亚胺酯转化为 N-酰基胺。从片段 5-7 开始(每个片段准备 7-8 个步骤,