Nitrenium Ion-Mediated Alkene Bis-Cyclofunctionalization: Total Synthesis of (−)-Swainsonine
作者:Duncan J. Wardrop、Edward G. Bowen
DOI:10.1021/ol2006117
日期:2011.5.6
The total synthesis of (−)-swainsonine from 2,3-O-isopropylidene-d-erythrose in 12 steps and an overall yield of 28% is reported. The pivotal transformation in our route to this indolizidine alkaloid is the formation of the pyrrolidine ring and C-8a/8 stereodiad through the diastereoselective, bis-cyclofunctionalization of an γ,δ-unsaturated O-alkyl hydroxamate. This transformation is believed to proceed
从2,3-苦马豆素- ( - )的总合成ö异亚丙基d报道-erythrose在12个步骤和28%的总产率。我们向这种吲哚里西啶生物碱的路线中的关键转化是通过 γ,δ-不饱和O-烷基异羟肟酸酯的非对映选择性双环官能化形成吡咯烷环和 C-8a/8 立体二联体。这种转化被认为是通过分子内捕获N-酰基-N-烷氧基氮丙啶鎓离子进行的,该N-酰基-N-烷氧基氮丙啶鎓离子是通过将单线态酰基氮鎓离子非对映选择性加成到侧链烯烃上而产生的。