الفهرس 
Aim of the workOnly 14 pages are availabe for public view
 |  | from | 262 |  |  |
| | | from | 262 | | |
Abstract
This thesis deals with studying the behavior of 2-substituted hydrazinecarbothioamides 1a,b and N,2-disubstituted hydrazinecarbothioamides 1c-e as electron donors towards some -deficient compounds and characterization the reaction products as well as the mechanism of their formation.
Reactions between 2-phenylhydrazinecarbothioamide 1a, N-substituted-2-phenylhydrazinecarbothioamides 1c-e and 2,3-dichloro-1,4-naphthoquinone (DCHNQ, 2a).
2-Phenylhydrazinecarbothioamide 1a and N-substituted-2-phenylhydrazinecarbothio-amides 1c-e reacted with 2,3-dichloro-1,4-naphthoquinone (DCHNQ, 2a) using Eschenmoser coupling reaction and in presence of triphenylphosphene as thiophile and Et3N as a base to give 3-(amino- and substituted amino)-1-phenyl-1H-benzo[f]indazole-4,9-diones 5a-d as a single product each in 74-87 % yield (Scheme 1).
All the new products 5a-d were confirmed by different spectral data such as 1H-, 13C-NMR spectroscopy in addition to mass spectrometry and elemental analyses. The structure of 3-(ethylamino)-1-phenyl-1H-benzo[f]indazole-4,9-dione 5c has been unambiguously confirmed by a single-crystal X-ray crystallography.
The formation of indazole derivatives 5a-d may be rationalized as depicted in scheme 2. At the first step, S-alkylation of hydrazinecarbothioamides with an electrophile and formation intermediate 9a-d. In the second step, the resulting thioether deprotonated and form the episulfide 10a-d after elimination a molecule of HCl. The episulfide 10a-d collapses via triphenylphosphine as a thiophile to give benzindazole derivatives 5a-d (Scheme 2).
Reactions between hydrazincarbothioamides 1a-e with ethenetetracarbonitrile (TCNE, 3):
2.2.1. Reactions between N-substituted-2-phenylhydrazinecarbothioamides 1c-e and ethenetetracarbonitrile (TCNE, 3).
The reaction between doubled molar amounts of (TCNE, 3) with one mole of N-substituted-2-phenylhydrazinecarbothioamides 1c-e in dry ethyl acetate with admission of air, concentrated and subjected to preparative layer chromatography, gave the mesoionic compounds 5-(1-amino-2,2-dicyanovinyl)-4-substituted-1-phenyl-4H-1,2,4-triazol-1-ium-3-thiolates 12a-c in 67-76 % yield as a single product (Scheme 3).
The structure of 12a-c was delineated from their spectroscopic properties, elemental analyses, as well as mass spectrometry. Moreover, the structure of 12a,b have been confirmed by a single crystal X-ray structure analyses .
For the formation of 12a-c, an initial CT-complexes may (but not have to) be intermediate stages, forming tetracyanoethane derivative 13, elimination a molecule of HCN from 13 gave the tricyanovinylation 14. Intramolecular nucleophilic attack of PhNH on C=C followed by cyclization afforded the bicyclic 16 via the intermediate 15. Compound 16 rearranges to form 17 and 18, and finally the highly stable mesoionic triazoliumthiolate derivatives 12a-c as depicted in (Scheme 4).
Reactions between 2-(substituted)hydrazinecarbothioamides 1a,b and ethenetetracarbonitrile (TCNE, 3).
On the other hand, treatment of 2-(substituted)hydrazinecarbothioamides 1a,b with 1.10 molar equivalent, of ethenetetracarbonitrile (TCNE, 3) in dry ethyl acetate at room temperature resulted in the formation of 2-[amino-(5-amino-2-(substituted diazenyl)-thiazol-4-yl)methylene]malononitriles 19a,b in 84-88% yield (Scheme 5). The structure of 19a,b was delineated from their NMR properties, mass spectrometry and elemental analyses. Moreover, the structure of (E)-2-[amino(5-amino-2-(phenyldiazenyl)thiazol-4-yl)methylene]-malononitrile 19a has been confirmed by a single crystal X-ray structure analysis .
Reactions between 2-substituted, N,2-disubstituted hydrazinecarbothioamides 1a-e and dimethyl acetylenedicarboxylate (DMAD, 4).
Equimolar amounts of hydrazinecarbothioamides 1a-e and dimethyl acetylene-dicarboxylate (DMAD, 4) in ethanol at reflux conditions resulted in the formation thiazolidinones 23a,b and 24a-c in 78-89% yield (Scheme 7).
Elemental analyses and mass spectra clearly revealed that the products were formed by the addition equimolar of (DMAD, 4) and 1a-e with elimination one molecule of methanol. There are possibilities for the formation of various isomers which would behave spectroscopically very similar. Hydrazinecarbothioamides, N1, N2, N4 and sulphur atom are the nucleophilic sites in compounds 1a-e.
To elucidate the tautomeric states and structure of the products as well as to characterize the products, we use IR, 1H NMR and 13C NMR as well as mass spectrometry. Rigorous structure proof comes from the single crystal X-ray structural analyses of 23b and 24b. The mechanism for the formation of products 23a,b and 24a-c is depicted in (Scheme 8). Nucleophilic attack of SH of 1a-e on the triple bond of 4 through the intermediate (C) (Fig. 4), followed by intramolecular nucleophilic attack of the NH2 of 1a,b at α-ester carbonyl group, the products 23a,b would be isolated, where via the intermediate (D) (Fig. 4) and nucleophilic attack of SH on the triple bond of 4 with elimination of one molecule of MeOH during the attack of N-hydrazinecarbothioamide at the carbonyl ester, the thiazolidin-4-ones 24a-c would be formed.