General Strategy for Synthesis of C-19 Methyl-Substituted <i>Sarpagine</i>/<i>Macroline</i>/<i>Ajmaline</i> Indole Alkaloids Including Total Synthesis of 19(<i>S</i>),20(<i>R</i>)-Dihydroperaksine, 19(<i>S</i>),20(<i>R</i>)-Dihydroperaksine-17-al, and Peraksine
作者:Rahul V. Edwankar、Chitra R. Edwankar、Jeffrey R. Deschamps、James M. Cook
DOI:10.1021/jo5016163
日期:2014.11.7
A detailed account of the development of a general strategy for synthesis of the C-19 methyl-substituted alkaloids including total synthesis of 19(S),20(R)-dihydroperaksine-17-al (1), 19(S),20(R)-dihydroperaksine (2), and peraksine (6) is presented. Efforts directed toward the total synthesis of macrosalhine chloride (5) are also reported. Important to success is the sequence of chemical reactions
详细介绍了 C-19 甲基取代生物碱合成总体策略的制定,包括 19( S ),20( R )-二氢peraksine-17-al ( 1 ), 19( S ),20 的全合成提出了( R )-二氢帕拉克辛( 2 )和帕拉克辛( 6 )。还报道了针对全合成粗盐氯化物( 5 )的努力。成功的重要因素是化学反应的顺序,其中包括关键的卤硼化反应、区域选择性硼氢化反应和受控氧化(以提供敏感的 C-20 烯醇化醛)。此外,最重要的 Pd 催化 α-乙烯基化反应首次扩展到手性 C-19 烷基取代的底物。高级中间体64的合成完成了塔卡品( 26 )的改进形式全合成,并为合成大环碱相关生物碱27-31提供了起点。同样,在环 A 氧化系列中扩展这种合成策略应该可以轻松进入双吲哚类 angustricraline、alstocraline 和 foliacraline 的北半球32b (图 4)。