1.3- Dithiol, 2,2-dibenzyl-4-phenyl

So far, only fused-ring 1,3-dithiolium salts have been synthesized in this way. The reason for this is that cis-ethylene- 1,2-dithiols were, until recently, difficult to obtain. Since, however, the cis-dithiol (208) can now be synthesized by the action of phenyl lithium or sodium alkoxide on isodithione (207),134 or by the cleavage of the cis-dibenzyl thioether (209),135 simple 1,3-dithiolium salts should now also be readily obtainable by this one-stage method. 

Dibenzyl-4-phenyl-l,3-dithiole 330 A suspension of l,3-diphenyl-2,2-propanedithiol (5.2 g, 0.02 mole), sodium hydrogen carbonate (4.0 g), and phenacyl bromide (4.0 g, 0.02mole) in ethanol (100 ml) is stirred at room temperature for 48 h, then cooled to —10°, treated with concentrated sulfuric acid (35 ml), and kept overnight at room temperature. Water then precipitates the dithiole which, on recrystallization from glacial acetic acid, forms yellow needles, m.p. 126.5-127.5° (4.4 g, 61 %). 

A suspension of l,3-diphenylpropane-2,2-dithiol, phenacyl bromide, and NaHCOg in ethanol stirred 48 hrs. at room temp., then 96%-H2S04 as dehydrating agent added at -10°, and allowed to stand overnight at room temp. 2,2-dibenzyl-4-phenyl-l,3-dithiole. Y 61%. F. e. s. E. Campaigne and F. Haaf, J. Heterocyclic Chem. i, 163 (1964). 

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See also in sourсe #XX -- [ ]

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