Electrosynthesis of Sulfur-containing Organic Compounds using a Reactive Sulfur-Graphite Electrode

利用有效的硫化学，可以将含硫有机化合物转化为目标化合物。因此，利用活性硫-石墨电极（S-C电极）研究硫官能团与有机化合物的结合是很有趣的。在目前的工作中，我们在以下化合物中引入了硫官能团：具有三氟甲基的累积烯、苯基磺酰丙烯和具有三氟甲基的苯基磺酰丙烯。目前的工作导致以下结论。(1)用S-C电极电还原含三氟甲基的聚丙烯腈，得到以1,2,5,6-四硫辛基为骨架的二聚体化合物。含三氟甲基和不含三氟甲基的累积烯的主要产物有很大差异，不含三氟甲基的累积烯产生含5个硫原子的7元环化合物，如五硫肽。(2)具有双氰基和磺酰基的3-芳基-2-苯基磺酰基丙烯腈在中等产率下得到在3位有两个或三个硫原子桥接的二聚5-芳基异噻唑。具有相邻氰基和磺酰基的2-苯基-3-苯基磺酰基丙烯腈与3-[(Z)-2-氰基-2-苯基乙烯基硫]-5-苯基异噻唑合成了由两个硫原子桥接的二聚体4-苯基异噻唑。这种含硫化合物的电合成的特点是消除了苯基磺酰基，同时加入了由单质硫电还原产生的多硫阴离子。(3) 2-（4-联苯基）-3-苯基磺酰基-3-三氟甲基丙烯腈是一种偶联化合物，由异噻唑氮原子和1,2-二硫烷骨架桥接而成。

Sulfur-containing organic compounds could be transformed to an aimed compound by applying the fruitful sulfur chemistry. Therefore, it is interesting to study incorporation of sulfur functionality into the organic compounds using a reactive sulfur-graphite electrode (S-C electrode). In the present work, we carried out introducing of sulfur functionality into the following compounds : cumulenes havingtrifluoromethyl groups, phenylsulfonylpropennitriles, and phenylsulfonylpropennitriles having a trifluoromethyl group. The present work leads to the following conclusions.(1) Electroreduction of cumulenes with trifiuoromethyl groups using the S-C electrode afforded dimeric compounds with a 1,2,5,6-tetrathiocin skeleton as the major products. There was a large difference in the main product between the cumulenes with and without trifluoromethyl groups, cumulenes without trifluoromethyl groups yielding 7-membered ring compounds with five sulfur atoms such as pentathiepins.(2) 3-Aryl-2-phenylsulfonylpropenenitriles having geminal cyano and sulfonyl groups gave dimeric 5-arylisothiazoles bridged with two or three sulfur atoms at the 3-position in moderate yields. 2-Phenyl-3-phenylsulfonylpropenenitrile havingvicinal cyano and sulfonyl groups yielded dimeric 4-phenylisothiazole bridged with two sulfur atoms together with 3-[(Z)-2-cyano-2-phenylethenylthio]-5-phenylisothiazole. This electrosynthesis of sulfur-containing compounds is characterized as elimination of a phenylsulfonyl group accompanying the addition of polysulfide anion(s) produced by electroreduction of elemental sulfur.(3) 2-(4-Biphenylyl)-3-phenylsulfonyl-3-trifluoromethylpropenenitrile afforded a coupling compound bridged with a nitrogen atom of isothiazole and 1,2-dithiolane skeleton.