1,2-Oxazolidines. Part V. Spiro and condensed biheterocyclic isomers from nitrones and 1,3-oxazolidin-2-ones

Abstract

The cycloaddition reaction between nitrones and substituted 1,3-oxazolidin-2-ones yields condensation products and spiro-compounds, each type of product containing a 1,2-oxazolidine nucleus. Their stereochemistry was elucidated by lanthanide shift analysis. The main spectrometric characteristics and the chemical behaviour of these new systems are discussed. Evidence is reported that the formation of the two types of isomeric adduct is controlled by a rearrangement process in competition with the cycloaddition.