合成路线1

This compound can be obtained by several related ways: 1) The reaction of 2-thioxo-1,3-dithiole-4,5-dicarboxylic acid (I) with methyl iodide in refluxing nitromethane gives 2-(methylsulfanyl)-1,3-dithiolium iodide (II), which is finally condensed with diisopropyl malonate (III), by means of NaH in refluxing THF. 2) The cyclization of sodium acetylide (IV) with sulfur and carbon disulfide gives 1,3-dithiole-2-thione (V), which is treated first with dimethyl sulfate and then with sodium perchlorate yielding 2-(methylsulfanyl)-1,3-dithiolium perchlorate (V). Finally, this compound is condensed with diisopropyl malonate (III) by means of NaH as before. 3) 1,3-Dithiole-2-thione (V) can also be obtained by cyclization of ethylene carbonate (VII) with carbon disulfide by means of K2CO3 and hexabutyldistannathiane. 4) 1,3-Dithiole-2-thione (V) can also be obtained by cyclization of ethylene trithiocarbonate (VIII) with acetylene at 110-45 C, although with low yields. 5) The selective hydrolysis of 2-(4-acetoxy-1,3-dithiol-2-ylidene)malonic acid diisopropyl ester (IX) gives the corresponding 4-hydroxy derivative (X), which is finally dehydrated with either, chlorosulfonic acid or sulfuric acid or thionyl chloride and DBU or phosphorous trichloride or phosphorous oxychloride.