Comparing and taming the reactivity of HWE and Wittig reagents with cyclic hemiacetals
作者:Jokin Carrillo、Anna M. Costa、Mireia Sidera、Jaume Vilarrasa
DOI:10.1016/j.tetlet.2011.07.121
日期:2011.10
lactol) with conjugated phosphoranes (stabilised Wittig reagents) and Horner–Wadsworth–Emmons reagents is disclosed. The HWE reaction has a strong bias to give oxolanes. On the other hand, stabilised Wittig reagents give unsaturated carboxyl derivatives of configuration E (major) and oxolanes (minor); the latter can be avoided by addition of CF3CH2OH or using morpholine amide phosphorane.
在(2 R,4 S)-4-羟基-2-甲基戊醛(作为半缩醛,乳醇)与共轭磷烷(稳定的Wittig)反应中形成E / Z和开环/环状异构体混合物的实用解决方案试剂和霍纳-沃兹沃思-埃蒙斯试剂已公开。HWE反应具有强烈的偏向于产生氧杂戊环。另一方面,稳定的Wittig试剂可得到构型E(主要)和氧杂戊烷(次要)的不饱和羧基衍生物;可以通过添加CF 3 CH 2 OH或使用吗啉酰胺磷烷来避免后者。