Alternative synthesis of imidazobenzisothiazole ring

Reaction of substituted 1-methylthio-4,5-dihydro[1,2]dithiolo[3,4-c]quinolin iodides with arylamines. Synthesis of novel 1,2-dithiolo[3,4-c]quinolin-1-ylidene(aryl)amines and 10-(arylimino)-7,10-dihydro[1,2]dithiolo[3,4-c]pyrrolo[3,2,1-ij]quinoline-4,5-diones

“…No information about the synthesis of 4,4-dimethyl-2-aryl-4,5-dihydroisothiazolo [5,4-c]quinoline-1(2H)-thione 4 has been found in the literature. Although the possibility of dithiole cycle's endo-sulfur substitution by a nitrogen atom has been shown, 19 the interaction of methylthio-dithiolium salt 2c with o-phenylenediamine yielding imidazathiazol 5 has been cited as the only example (Scheme 1). Thus, there is still no conclusive evidence that in the reaction of methylthio-dithiolium salts with arylamines the attack of amino groups targets exclusively the exo-sulfur atom.…”