Reactions of the Chlorine Complex of Tetrahydrothiophene

Article abstract of DOI:10.1021/jo00216a006

The chlorine complex of tetrahydrothiophene (THT) undergoes the Pummerer reaction to yield not only the expected 2-chloro- and 2,3-dichlorotetrahydrothiophene products but also 1-(2-chlorotetrahydro-3-thienyl)-tetrahydrothiophenium chloride (10), which upon hydrolysis yields 1-(tetrahydro-2-hydroxy-3-thienyl)tetrahydrothiophenium chloride 3 and upon elimination of HCl produces 1-(4,5-dihydro-3-thienyl)tetrahydrothiophenium chloride (2).The sulfonium 10 was formed by the addition of the chlorine-THT complex to the Pummerer-derived 2,3-dihydrothiophene.The sulfonium formation was monitored in CCl4, CH2Cl2, and liquid SO2 by proton NMR, and the addition of the complex to cyclohexene, dihydrofuran, styrene, and thiophene was studied.There was a dramatic increase in reactivity of the complex in sulfur dioxide both to addition and substitution type reactions.