Synthesis and 1H n.m.r. spectroscopic analysis of some 3,7-dioxabicyclo[3.3.0]octane lignans

Abstract

Within the framework of a synthetic project towards the preparation of the natural germination inhibitor 2,6-diaryl-3,7-dipxabicyclo[3.3.0]octane, several molecules with the same bicyclic skeleton were prepared and their ¹H n.m.r. spectra are described in detail. For the symmetrical systems particularly, the spectra exhibited second-order features and were interpreted analytically or, when necessary, by computer simulation. These n.m.r. data enabled a conformational analysis of the ring system.