5-Substituted 1,2,3,4-thiatriazoles

Substituted 1,2,3,4-thiatriazoles (93) are alkylated only under very forcing conditions with triethyloxonium fluoroborate, but then give the expected products (94) (75JOC431). 

Table 1 Assignments of in-plane vibrations in 5-substituted 1,2,3,4-thiatriazoles.

Thiatriazoles (see Section II). 5-Substituted 1,2,3,4-thiatriazoles undergo quaternization at N-3 [Eq. (5)]. The study using H, 15N, and 13C NMR to prove the structure of the product serves as a model not only for this ring system, but for others as well.22... 

The generation of intermediate azidothiocarbonyl compounds 10 followed by 1,5-electrocyclic reaction leads to 5-substituted 1,2,3,4-thiatriazoles 9. This mechanism has been proposed in reactions of various derivatives of thiohy-drazides 136 with either nitrous acid or arenediazonium salts, and in reactions of thiophosgene (or dithiocarboxylates) 135 (X = C1, SR) with either sodium or trimethylsilyl azide (Scheme 32) <1984CHEC(6)579, 1996CHEC-II(4)691,... 

This section deals with the chemistry of 5-substituted 1,2,3,4-thiatriazoles (1), A2- (2) and A3-l,2,3,4-thiatriazolines (3) (4,5- and 2,5-dihydro-l,2,3,4-thiatriazoles, respectively), 3,5-disubstituted 1,2,3,4-oxa- (4) and -thia-triazolium salts (5) and the novel 1,2,3,4-selenatriazoles (6). This last group has a close chemical resemblance to 1,2,3,4-thiatriazoles. 5-Substituted 1,2,3,4-oxatriazoles have not been isolated. In contrast to the 5-substituted... 

IR and mass spectra of 5-substituted 1,2,3,4-thiatriazoles have been reviewed (76AHC(20)145). Recently, in-plane normal vibration modes of 5-amino-l,2,3,4-thiatriazole and 5-mercapto-l,2,3,4-thiatriazole have been tentatively assigned in the solid state on the basis of a normal coordinate analysis, transferring force constants from related molecules... 

When the reaction of the isothiocyanates is conducted with HN3 or MesSiNj, a wide variety of 5-substituted 1,2,3,4-thiatriazoles 129 are obtained . ... 

The compounds considered to be thiatriazoline-5-thiones were later shown in fact to be 5-substituted thiatriazoles (Section V). Therefore the assignments by Rao et al.1 of ring breathing and CH out-of-plane deformations to the supposed two different systems of 4- and 5-substituted thiatriazoles all correspond to 5-substituted thiatriazoles.11 The ring breathing absorptions are found at 1320-1260, 1238-1215,... 

Accordingly, 5-substituted-amino-l,2,3,4-thiatriazoles (Tables III and IV) are formed quite generally from 4-substituted-thiosemicarb-azides. When the substituent is an aryl group these initial products are isomerized to 5-mercaptotetrazoles on treatment with alkali whereas this is not the case when the substituent is an alkyl group. 

The most characteristic feature of the infrared spectra of all 5-mono- and -di-substituted-amino-l,2,3,4-thiatriazoles is a strong band in the 1540-1590 cm range, which without doubt is due to the C=N and N=N stretching vibrations of the heteroaromatic ring system. Various infrared bands between 889 and 1122 cm have been assigned to skeletal vibrations of the thiatriazole ring and a band... 

The third volume of this series covers three specific groups of compounds the carbolines (reviewed by R. A. Abramovitch and I. D. Spenser), the thiatriazoles (K. A. Jensen and C. Pedersen), and the pentazoles (I. Ugi). The remaining four chapters deal with topics of general chemical interest from the heterocyclic viewpoint the quaternization of heterocyclics (G. F. Duffin), carbene reactions (C. W. Rees and C. E. Smithen), applications of the Hammett equation (H. H. Jaffe and H. Lloyd Jones), and some aspects of the nucleophilic substitution of heterocyclic azines (G. Rluminati). 

L abbe has studied the rearrangement reactions of 1,2,3-thiadiazoles to differently substituted 1,2,3-thiadiazoles <1983CC588>. He also studied many 5-azido-l,2,3-thiadiazoles 33 that rearranged to 1,2,3,4-thiatriazoles 34 (Equation 5) <1988BSB163>. He even found that l,2,3-thiadiazole-4-carboxaldehydes 35 upon treatment with amines underwent thermal rearrangement to 1,2,3-triazoles 36 (Equation 6) <1993J(P1)1719>. 

The 4-substituted-5-sulfonylimino-l,2,3,4-thiatriazoles also rearrange on reaction with unsaturated reagents [75JOC1728 80AG(E)276 82T3537 ... 

Treatment of 5-substituted amino-1,2,3,4-thiatriazoles (283) with aqueous base results in competitive rearrangement to 5-thiotetrazoles (284) and fragmentation to isothiocyanates (285) and... 

The highly explosive 5-chloro-l, 2,3,4-thiatriazole (prepared from thiophosgene and sodium azide) has been used for the preparation of 5-substituted 1,2,3,4-aminothiatriazoles and certain 5-alkoxy-thiatriazoles (Section 4.19.7). Great care should be exercised in handling any reaction product of thiophosgene and azide ion. In particular the reaction of 5-chloro-l,2,3,4-thiatriazole with azide ion yielded a product assumed to be 5-azido-l,2,3,4-thiatriazole which gave rise to explosion as a suspension in water (61J0C1644>. 

When a substituted propargyloxy-l,2,3,4-thiatriazole (158) was decomposed, 5-oxo-thiatriazoline (159) was isolated along with the main product, the allenylisocyanate (160) (Equation (12)). 

A-Substituted 5-amino-1,2,3,4-thiatriazoles (13) were obtained by Freund and Hempel in 1895 by treating thiosemicarbazides with nitrous acid (Equation (15)) <1895CB74>. This method has been used by others to prepare a number of different A-substituted 5-aminothiatriazoles (13) in good yields ( 80%) <81JIC1087>. 

Allyloxy- (146) and propargyloxythiatriazoles (154) are obtained in a similar way by treating the corresponding chlorothioformates with sodium azide (92AG865). However, substituted allyloxy (150) and propargyloxy thiatriazoles (158) were obtained from 5-chloro-l,2,3,4-thiatriazole (175) in the presence of sodium hydride and the corresponding alcohols (35-70% yield) <92AG865>. 

Thiadiazoles rearrange to variously substituted 1,2,3-thiadiazoles (83CC588). Many 5-azido-1,2,3-thiadiazoles rearrange to 1,2,3,4-thiatriazoles (Scheme 9) (88BSB163). 

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