Dedicated to Professor Ernst Schaumann
Abstract
The synthesis of postulated 2H,6H-1,5-dithiocines from isonitriles and acetylenedicarboxylates or dibenzoylacetylene
in the presence of elemental sulfur was repeated. The products do not possess the
structure of eight-membered sulfur heterocycles, but isothiazole-3(2H)-thiones were formed instead. This structural corrigendum was confirmed not only
by a critical consideration of the 13C NMR spectroscopic data and by the correction of the MS spectra and the values of
the elemental analyses but also by X-ray crystallographic structure determination.
Several reaction mechanisms are discussed to explain the generation of the observed
isothiazole-3(2H)-thiones.
Key words
alkynes - heterocycles - multicomponent reaction - nucleophilic addition - ring closure
- spectroscopy - structure analysis - sulfur