Studies on the Synthesis of (−)-Gymnodimine. Subunit Synthesis and Coupling
作者:James D. White、Laura Quaranta、Guoqiang Wang
DOI:10.1021/jo062396o
日期:2007.3.1
portion of gymnodimine was synthesized via Diels−Alder cycloaddition of a 1,2,3-trisubstituted diene to a symmetrical dienophile obtained from Meldrum's acid. Differentiation of carbonyl groups in the cycloadduct was made by an intramolecular reaction with a neighboring alcohol to form a γ-lactone. Linkage of the two subunits at C18−C19 was accomplished by using a B-alkyl Suzuki coupling in which a borane
合成了海洋藻毒素(-)-gymnodimine的两个主要亚基。经由高立体选择性碘介导的带有双2,6-二氯苄基(DCB)醚的无环烯烃的环化反应,制备了代表毒素C10-C18的三取代四氢呋喃。在该过程中顺式-2,5-二取代的四氢呋喃的形成符合Bartlett和Rychnovsky提出的DCB基团的立体定向作用。通过将1,2,3-三取代的二烯与由麦德鲁姆酸制得的对称的亲二烯体进行狄尔斯-阿尔德环加成反应,合成了与裸草二胺的C1-C8,C19-C24部分相对应的环己烯亚基。通过与相邻醇的分子内反应以形成γ-内酯来进行环加合物中羰基的区分。E)-碘代烯烃连接在四氢呋喃区段的C16处。随后的转化将官能团定位在偶联的产物中,以用于将来的大环化事件,该事件将关闭裸草二胺的15元环。