Highly Diastereoselective Approach toward (±)-Tetraponerine T6 and Analogues via the Double Cycloisomerization−Reduction of Bis-alkynylpyrimidines
作者:Joseph T. Kim、Jason Butt、Vladimir Gevorgyan
DOI:10.1021/jo049259g
日期:2004.8.1
A new, short, and efficient approach toward tricyclic alkaloids, involving the double cycloisomerization−reduction of bis-alkynylpyrimidines 3a−m, has been developed. The requisite bis-alkynylpyrimidines 3a−m were readily prepared via regioselective sequential Sonogashira coupling reactions of dibromopyrimidines 1. Bis-alkynylpyrimidines 3a−m were converted into the 5−6−5 tricyclic heteroaromatic cores
已经开发出一种新的,短而有效的三环生物碱方法,涉及双炔基嘧啶3a - m的双环异构化-还原。通过二溴嘧啶1的区域选择性顺序Sonogashira偶联反应可轻松制备必要的双炔基嘧啶3a - m。双-炔基嘧啶3a - m通过Cu(I)辅助的双环异构化反应转化为5-6-5三环杂芳族核4a - m。反应逐步进行,这通过分离单热解中间体5得到证实。。5的结构通过2D NMR和独立合成进行分配。在标准条件下5的环异构化得到三环4g,收率89%。双吡咯并嘧啶4d,4g和4i在酸性介质中的PtO 2催化氢化反应提供了稳定的am鎓衍生物11a,11b和11c。用LiAlH 4进一步还原后者,使得(±)-四皂角T6及其类似物具有高度非对映选择性的全合成。