Thiobenzoylthioglycolic acid

Tetranitrofluorenone, 42, 95 Tetraphenyltin from phenyllithium and allyltriphenyltin, 41, 30 Teteolic acid, 42, 97 Thiobenzoylthioglycolic ACID, 42, 100... 

The dehydration of thiobenzoylthioglycolic acid (135, R = Ph, R = H) with acetic anhydride-boron trifluoride was initially described as yielding the meso-ionic l,3-dithiol-4-one (134, R = Ph, R = H), but subsequent studies showed that the product was in fact the 5-substituted derivative 134, R = Ph, R = COCHjSCSPh. Authentic meso-ionic l,3-dithiol-4-ones (134) have recently been prepared (85-90% yield) by the cyclodehydration of the acids (135) with acetic anhydride-triethylamine at 0°-10°. Examples include anhydro-4-hydroxy-2-phenyl-l,3-dithiolium hydroxide (134, R = Ph, R = H) described as scarlet needles, m.p. 113°—115° this compound is sensitive to moisture. Anhydro-4-hydroxy-2,5-diphenyl-1,3-dithiolium hydroxide (134, R = R = Ph) was obtained as gold lustered, deep violet needles,... 

It has been shown (76JOC1724) that a previously described compound (65BCJ596), prepared by treatment of thiobenzoylthioglycollic acid (264) with acetic anhydride in the presence of boron trifluoride, is indeed the acylated 1,3-dithiolone (265) and not the claimed 2-phenyl-l,3-dithiolylium-4-olate. The latter can be prepared from thiobenzoylthioglycollic acid (264) and acetic anhydride-triethylamine (76JOC1724) or acetic anhydride-dicyclohexyl-ethylamine (76CB740). 

Thiobenzoylthioglycolic acid has been prepared by the interaction of potassium dithlobenzoate and alkali chloroacetate. " The required intermediate, dithiobenzoic acid, has been obtained from phenylmagnesium bromide and carbon disulfide, -or by the condensation of benzaldehyde and hydrogen polysulfides, or most conveniently by treatment of benzotrichloride with potassium hydrogen sulfide. - The last procedure has been adapted here to afford improved yields. 

Thiobenzoylthioglycolic acid is a useful thiobenzoylating agent,and the resulting products find application for the synthesis of various heterocycles. These applications of thiobenzoylthiogly colic acid have recently been reviewed... 

The reaction of thiobenzoylthioglycolic acid (228) with acetic anhydride in the presence of boron trifluoride results in the formation of the dithiolone (229) (Equation (39)) <76JOCi724>. 

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