Synthesis of (±)tylophorine by the intramolecular cycloaddition of an azide with an ω-chloroalkene
作者:William H. Pearson、Rajesh Walavalkar
DOI:10.1016/s0040-4020(01)89538-7
日期:1994.1
alkaloid (±)- tylophorine 5 in 82% yield. These reactions proceed by intramolecular 1,3-dipolar cycloaddition of the azide onto the alkene followed by loss of nitrogen from the triazoline intermediate to give an imine The imine is N-alkylated in situ by the pendant benzyl chloride to provide an iminium ion, which is reduced by sodium borohydride to afford the indolizidines. The synthesis of (±)-tylophorine
将(Z)-1-(2-氯甲基)苯基-5-叠氮基-1-烯10在苯中于120°C环化,然后用硼氢化钠处理,生成1,2,3,5,10,10a-六氢吡咯[ 1,2- b ]异喹啉11的产率为71%。(Z)-2,3,6,7-四甲氧基-9-(5-叠氮基-1-戊烯基)-10-氯甲基菲3的类似环化反应得到菲咯啉吲哚生物碱(±)-酪氨酸5,产率为82%。这些反应通过叠氮化物的分子内1,3-偶极环加成反应进行,然后从三唑啉中间体中损失氮原子得到亚胺。亚胺在原位被N-烷基化通过苄基氯侧链得到亚氨基离子,其被硼氢化钠还原得到吲哚并核苷。(±)-酪氨酸的合成是从高纯酸分11步完成的,总产率为5%。