Annulation of a 1,3-dithiole ring to a sterically hindered <i>o</i>-quinone core. Novel ditopic redox-active ligands
S. V. Norkov, Anton V. Cherkasov, Andrey S. Shavyrin, Maxim V. Arsenyev, V. A. Kuropatov, V.K. Cherkasov
Abstract
The fused 1,3-dithiole spacer seems to be very suitable for the functionalization of sterically hindered o -quinones with additional groups capable of coordination of metal ions and/or possessing a redox activity. An effective method for the synthesis of sterically hindered o -quinones containing 1,3-diketonate, dinitrile and p -quinone-methide functional groups at the periphery of the ligand has been developed. The novel compounds have rigid and conjugated structures and exhibit properties typical of o -quinones. A study of their monoreduced semiquinone derivatives reveal that the spin density is delocalized across the whole molecule, including peripheral fragments. The first stable o -quinone derivative bearing an annulated thiete heterocycle has been isolated and characterized.