An Asymmetric Tandem Conjugative Addition-Intramolecular Cyclisation Process to Provide Functionalised 3,6-Dihydropyrans and 4,5-Epoxytetrahydropyrans
作者:Silvia Catalán-Muñoz、Constanze A. Müller、Steven V. Ley
DOI:10.1002/ejoc.200901145
日期:2010.1
The synthesis of 3,6-dihydropyrans and 4,5-epoxytetrahydropyrans starting from enantiomerically pure β-hydroxy aldehyde (prepared by an organocatalytic aldol reaction) is described. The key step is a tandem sequence, which consists of a base-promoted conjugative addition to a vinyl onium salt, followed by either an intramolecular Wittig process to provide 3,6-dihydropyran derivatives or an intramolecular