Conformational analysis of some spiro and polyspiro 1,3-dioxane compounds with axial and helical chirality

Abstract

Some spire and trispiro 1,3-dioxane compounds are discussed in terms of their axial and the helical chirality (all rings are six-membered). The influence of conformation on the number of isomers and on their interrelationship has been followed by means of high resolution and dynamic NMR experiments using the diastereotopicity of the proton and carbon atoms. Interconversions between configurational isomers (presenting three chiral elements) without the breaking of bonds are reported.