Conformational preferences of oxy-substituents in butenolide–tetrahydropyran spiroacetals and butenolide–piperidine spiro-N,O-acetals
作者:Sébastien Naud、Sarah J. Macnaughton、Bryony S. Dyson、Daniel J. Woollaston、Jonathan W. P. Dallimore、Jeremy Robertson
DOI:10.1039/c2ob06849d
日期:——
of a series of oxy-substituted butenolide spiroacetals and spiro-N,O-acetals by oxidative spirocyclisation of 2-[(4-hydroxy or 4-sulfonamido)butyl]furans. The axial–equatorial preference of each oxy-substituent is investigated (NMR) by an acid-catalysed thermodynamic relay of configuration between the spiro- and oxy-centres. The axial site is preferred for most oxy-substituents at synthetically useful
我们描述了2-[(4-羟基或4-磺酰胺基)丁基]呋喃的氧化螺环化反应,合成了一系列氧取代的丁烯内酯螺缩醛和螺-N,O-缩醛。通过在螺中心和氧中心之间构型的酸催化热力学继电器研究了每个氧取代基的轴向-赤道偏爱度(NMR)。对于大多数含氧取代基,在合成上有用的水平,轴向位点是优选的。根据稳定的纱布效应和溶剂化的影响讨论了这种偏爱的潜在来源。这些结果与包括AL-1和相关化合物的双(炔)烯醇醚螺缩醛的合成有关。