1,1''-Binaphthyl-2,2''-dithiol is used in the preparation of chiral, atropisomeric organosulfur compounds.
the original procedure of 1,1'-Binaphthyl-2,2'-dithiol used Ullman coupling of 1-bromo-2-naphthalenesulfonic acid. The intermediate 1,1′-binaphthalene-2,2′-sulfonic acid can be resolved with strychnine. Lithiation of 2,2′- dibromo-1,1′-binaphthalene with t-butyllithium, quenching with sulfur, and reduction of the resulting disulfide is an alternative preparation of the racemic dithiol. More practical procedures entail Newman-Kwart rearrangement of the thioester derived from binaphthol and dimethylthiocarbamoyl chloride, followed by hydrolysis. Use of enantiomerically pure binaphthol as starting material gives the enantiomerically pure reagent. Another resolution procedure involves enantioselective oxidation of sulfides which can be further transformed into the dithiol.
(+/-)-1,1'-Binaphthyl-2,2'-dithiol oxidizes easily to the disulfide and should be stored under inert atmosphere. Use in a fume hood.
