Tetrazole-5-thione

Tetrazole-5-thiones Anhydro-5-mercapto-l,2, 4-tetrazolium Hydroxides) (295)... 

The salts (294) (Section VII, J, 1) are useful intermediates for the preparation of other meso-ionic systems by reaction with appropriate nucleophiles. Thus, reaction with sodium sulfide in dimethyl formamide yields the l,2,3,4-tetrazole-5-thiones (295), a new class of meso-ionic heterocycle. The 1,3-diphenyl derivative (295, R = = Ph) has a... 

The last part of this section is devoted to the first meso-ionic heterocycle to be synthesized. It is called dehydrodithizone, and it is the most widely investigated representative of meso-ionic 1,2,3,4-tetrazole-5-thiones (413). Dehydrodithizone was first obtained by Emil Fischer in 1882 and his collaborator in this investigation was E. Besthom, who subsequently discovered another meso-ionic compound, Besthom s Red (93a). 

It is very important to emphasize that the terms meso-ionic compound and sydnone are not interchangeable. The term sydnone should be used only for the heterocyclic system (1). It just causes confusion if the word sydnone is used to describe other heterocyclic systems, although they are meso-ionic. The term sydnone should not be used to describe derivatives of l,3,2-oxathiazol-5-one (169) and 1,2,3,4-tetrazole-5-thione (413). ... 

Meso-ionic l,2,3,4-tetrazol-5-ones (289) react with triethyloxonium tetrafluoroborate, yielding salts (294)197 that react with sodium sulfide in dimethylformamide, giving meso-ionic l,2,3,4-tetrazole-5-thiones (295).207... 

Gas-phase thermolysis of substituted tetrazoles (46a,b and 48), the 1,4-disubstituted 1,4-dihydro-5//-tetrazol-5-oncs (49a-f) and the 1,4-disubstituted 1,4-dihydro-5/7-tetrazol-5-thiones (50b,c,e-h) have been monitored by photoelectron spectroscopy.27... 

Interestingly, although the thione form of neutral tetrazoles prevails, the alkylation and acylation of tetrazole-5-thione anions afford exclusively products of addition to the sulfur atom (cf. Section 6.07.7.5), suggesting that under specific conditions formation of the 5-mercapto form is possible. 

The synthesis and reactivity of tetrazole-5-thiones are considered in Section 6.07.7.5. A preparation of sulfone 304 in two steps from the corresponding tetrazole-5-thione 303 by alkylation and subsequent oxidation has been described (Scheme 38) <2006JOC360>. 

Preparative methods and chemical properties of tetrazole-5-thiones (tetrazole-5-thiols) have been summarized in a review <2004RJ0447>. The most significant results in this field were obtained in the last decade while studying the alkylation of tetrazole-5-ylthiones (tetrazole-5-ylthiols), and the oxidation of 1-substituted 5-alkylsulfatetrazoles to the corresponding sulfinyl and sulfonyl derivatives. Special attention should be paid to the Kocienski-modified Julia olefination based on the application of 5-alkylsulfonyltetrazoles to the activation of chemical reactions. 

Fig. 28.1.5. l,4-Dihydro-5H-tetrazol-5-thione 3 and 5-thiono-l,2,4-oxazolidinone 4 as precursors of insecticidal carbodiimide 5. 

This concept has been extended in two further examples. Based on a literature report that l,4-dihydro-l-phenyl-5H-tetrazol-5-thiones photochemically form carbodiimides by extrusion of nitrogen and sulfur [52], and the expectation that 5-thiono-l,2,4-oxazolidinones may similarly lose carbon dioxide and sulfur to form carbodiimides, 3 and 4 were prepared as potential proinsecticides. Both compounds were efficiently converted into the carbodiimide 5 by ultraviolet light and displayed the expected strong insecticidal and acaricidal properties in vivo (Fig. 28.1.5) [53-55]. 

Diamino-1,3,4-thiadiazole, D-60049 l -Tetrazole-5-thiol 5-Me, in T-60174 Tetrazole-5-thione 1-Me, in T-60174... 

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