New Synthetic Route for 2-Chloro-1,3,2-Dithiastibolane Involving a Skeletal Substitution Reaction

Abstract

Herein we report the synthesis, characterization and conformational studies of 2-chloro-1,3,2dithiastibolane 2. Unexpectedly, treatment of 2-chloro-l,3,2-dithiaphospholane 1 with SbF 3 did not lead to the replacement of the chlorine of compound 1. Instead, compound 2 was obtained in a rather high yield, via a skeletal substitution reaction. This is the first example of a skeletal substitution reaction involving the replacement of phosphorus by antimony. Compound 2 was characterized on the basis of 'H and 13 C{'H} NMR studies, mass spectroscopy and elemental analyses. A semi-empirical calculation of 2 was carried out and the results pointed to only one non planar conformation: a large half chair due to the size of antimony, which explains the magnetic equivalence of the four hydrogen atoms.