Synthesis of spirocyclic 1,3-oxazines via three-component reactions of α,β-unsaturated N-arylaldimines, dialkyl acetylenedicarboxylate and quinones

A series of structurally diverse spirocyclic 1,3-oxazines were conveniently prepared from three-component reactions of alpha,beta-unsaturated N-arylaldimines, dialkyl acetylenedicarboxylate and quinones in dry acetonitrile without catalyst. Various quinones including p-benzoquinone, 1,4-naphthoquinone, acenaphthenequinone, and phenanthrenequinone as well as benzil were successfully used in the reaction to give the corresponding spirocyclic 1,3-oxazines in good yields. The diastereoisomers of the obtained spirocyclic 1,3-oxazines were elucidated by H-1 NMR spectra and single crystal structures. (C) 2015 Elsevier Ltd. All rights reserved.