3H-1,2-Dithiole

Table 26 Cycloadditions of 3-benzylidene-5-phenyl-3H-1,2-dithiole 189 with heterocumulenes 190 (Equation 49)...

Dithiolium 3-Chlor-4-ethyl- -chlorid E8a, 494 (4-C2H5 — 3-oxo — 3H-1,2-dithiol +... 

H-(Pyrano 4,3-b -l-oxa-6,6a(24)-dithia-pentalene) 6,8-Dioxo-5-(3H-1,2-dithiol-3-yliden)-6,8-dihydro- E8a, 616 (3-SR —1,2-dithiolium + 2,4,6-Trioxo-H4-pyran/Py)... 

Indolizin 2-Ethoxycarbonyl-l-methylthio-3-thiocyanat- E6b/1, 384 [4-COOR — 5-(2-py)— 3-thiono—3H —1,2-dithiol f NaCN/H3C—I]... 

Table 8 Comparative yields of 3H-1,2-dithiole-3-thiones 258 from 3-oxoesters 264a and 264f-i using P4S10/HMDO reagent or LR...

In order to determine the exact mechanism, structure-activity studies were performed OPZ and 5-(4-methoxyphenyl)-3H-l, 2-dithiole-3-thione were shown to be similarly effective on the inhibition of preneoplastic lesions induced by AFBi, while treatment with 1,3-dithiole-2-thione was without effect [31]. The efficacy of OPZ compared to other dithiolethiones was further studied by evaluating the effects of 17 dithiolethiones on acute hepatotoxicity of AFBl in rats [32]. The results demonstrated that, although several dithiolethiones were more active than OPZ in inhibiting toxicity, no structural motif linked to these chemoprevention properties could be identified. 

The action of Grignard reagents on N-(5-aryl-3H-l,2-dithiol-3-ylidene)-arylamines (10) provides the 1,3-bifunctional reagents (11)," which have proved to be versatile starting materials in heterocyclic syntheses. Their oxidation with iodine produces isothiazolium iodides (12) in 29—34% yield. 

Thiazol 3,5-Bis-[methylthio]-4-methoxycarbonyl- E8a, 731 [5-NH2 - 4-COO R - 3-thiono-3H-dithiol + Na0H/(R0)2S02]... 

The preparation of 3-amino-1,2-benzisothiazole 249 can be done in different ways. A weU-known method started from 248, which was treated with a formamide solution containing NH3 [80] (Scheme 62). An alternative method started from hydroxylamine and N-(3H-benzo[c]l,2-dithiol-3-ylidene) acetamides (250) (obtained from 248 and thioacetic acid), and gave i r-(3-benzisothiazolyl)acetamide (251) (52-62%) hydrolyzed to amine 249 (48-88%) [81]. 

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