Scientific publications
Comparing and taming the reactivity of HWE and Wittig reagents with cyclic hemiacetals
Oct 5, 2011
| Magazine:
Jokin Carrillo, Anna M. Costa, Mireia Sidera, Jaume Vilarrasa
Abstract
A practical solution to the formation of mixtures of E/Z and open/cyclic isomers in the reaction of (2R,4S)-4-hydroxy-2-methylpentanal (as its hemiacetal, a 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.
CITA DEL ARTÍCULO https://doi.org/10.1016/j.tetlet.2011.07.121
