Thiomethoxymethyl hexachloroantimonate

When thiomethoxymethyl hexachloroantimonate was treated with pyridine, a methylthio derivative 28 was isolated in low yield in addition to the expected chlorinated sulfides (71T4209). Several A,/V -haloalkyl-bis-4,4 -pyridiniumethenes 29 have been reported in a Japanese patent (80JAP75479). These compounds are promising candidates for the construction of electrochromic display devices (Scheme 7). 

The condensation of aldehydes with thiocyanoacetic esters, catalysed by potassium fluoride or potassium carbonate, gave as minor products yV-carbamoyl-2-imino-5-alkyl(or aryl)-l, 3-oxathiolan-4-carboxylic esters, in which the 4,5-c/j-isomers predominated according to n.m.r. spectroscopy. l,3-Oxathiolan-2-thione was converted into dimethyl 1,3-dithiol-2-one-4,5-dicarboxylate and ethylene on treatment with dimethyl acetylene-dicarboxylate, and the transformation of methyl 2-methoxycarbonyl-methyl-1,3-oxathiolan-2-carboxylate into dimethyl-5,6-dihydro-l, 4-oxa-thiin-2,3-dicarboxylate by chlorination at low temperatures found analogy in the reactions of 2,2-dialkyl-l,3-oxathiolans. Thiomethoxymethyl hexachloroantimonate reacted with potassium t-butoxide to give mainly 3,5,5-trimethyl-l,3-oxathiolanium hexachloroantimonate the mechanism of this remarkable reaction was not settled. ... 

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