Gold(I) catalysed cycloisomerisation of β-hydroxy propargylic esters to dihydropyrans/2H-pyrans via allene intermediates
作者:Ramesh Kotikalapudi、K.C. Kumara Swamy
DOI:10.1016/j.tet.2013.07.003
日期:2013.9
Efficient cycloisomerisation of β-hydroxy propargylic esters to dihydropyrans/2H-pyrans via 1,3-carboxylate migration followed by regioselective hydroxyl addition to the transient allene intermediate catalysed by Ph3PAuCl/AgSbF6 is presented. Similar reactions on phosphorylated precursors led to phosphono-furans and phosphono-pyrans. In a few cases, self-condensation of β-hydroxy propargylic esters
提出了通过1,3-羧酸酯迁移,随后将区域选择性羟基加成到Ph 3 PAuCl / AgSbF 6催化的瞬时烯丙基中间体中,将β-羟基炔丙基酯有效地环化为二氢吡喃/ 2 H-吡喃的方法。在磷酸化前体上的类似反应导致膦酰呋喃和膦酰吡喃。在少数情况下,观察到β-羟基炔丙基酯通过亲核催化取代成大环而自缩合。主要产品通过X射线结构确定来表征。