NEW SUBSTRATES FOR THE PREPARATION OF ELECTROACTIVE MATERIALS - THE SYNTHESES OF CHIRAL TETRATHIAFULVALENE DERIVATIVES WITH HYDROXY-FUNCTIONALIZED BUTANE-1,4-DITHIO BRIDGES

The syntheses of two derivatives of TTF containing (2R,3R)-2,3-dihydro xybutane-1,4-dithio bridges is described, for use in the preparation o f chiral hydrogen bonded radical cation salts as potentially electroac tive materials. The bridges are introduced by reaction of 2-thioxo-1,3 -dithiole-4,5-dithiolate with 1,4-disubstituted derivatives of bis-O-p rotected butane-2,3-diol to give a bicyclic thione. The X-ray crystal structure of the isopropylidene ketal derivative shows that all four s p(3) carbon atoms in the eight-membered ring are displaced to the same side of the dithiole plane. Ease of deprotection led to the use of me thoxyethoxymethyl (MEM) protecting groups rather than the ketal. Treat ment of the bis-MEM-protected bicyclic thione with mercuric acetate an d acetic acid led not only to exchange of the exocyclic sulfur for oxy gen but also to removal of just one of the MEM groups, which may have wider synthetic applications.