Tetrazoline

Aziridinimine derivatives are also accessible by the photochemically induced extrusion of nitrogen and ring contraction of simple alkylidene tetrazolines (424) <75AG(E)428). Thus, Pyrex-filtered photolysis of (424) at -60 °C quantitatively afforded the aziridinimines (425). 

A novel principle of diaziridine synthesis was found in nitrogen extrusion from tetrazolines (275). Af-Aryldiaziridines (276) almost unaccessible by older procedures thus become available (74CL185). 

Photolytic nitrogen extrusion from tetrazoline derivatives (283) and (284) permits further syntheses of diaziridin-ones (285a) and -imines (285b) respectively (75AG(E)428). Thermal carbon dioxide extrusion from a five-membered precursor can also give a diaziridinimine (75JOC3112). 

Tetrazol-5-imine, 2-methyl-dipole moment, 5, 795 (56JA4197) Tetrazoline-5-thione, 1-phenyl- C NMR, 5, 805 (77JOC3725)... 

Tetrazoline-5-thione, 1-phenyl-methylation, 5, 819 in photography, 5, 837 reactions, 5, 823 Tetrazoline-5-thiones fragmentation, 5, 810... 

Tetrazolin-5-one, l-arylsulfonyl-4-butyl-polymerization, 5, 838 Tetrazolin-5-one, 1-methyl-methylation, 5, 819 Tetrazolin-5-ones 1,4-disubs tituted synthesis, 5, 831 1-substituted alkylation, 5, 794 tautomerism, 5, 794 Tetrazolinyl radicals, 5, 801 1,2,3,4-Tetrazolium-5-aminide nomenclature, 1, 35... 

The stem suffixes -etine and -oline have been widely used to indicate a single double bond (thus intermediate unsaturation) in four- and five-membered rings containing a nitrogen atom (e.g. tetrazoline = dihydrotetrazole). They are no longer recommended by lUPAC, however. 

Isocyanates132 react with appropriate azide salts to yield 1-substituted tetrazoline-5-ones (68) (Eq. 13). By contrast, isothiocyanatesi33,i34 react with hydrazoic acid to yield the aminothiatriazole (69) which rearranges to the thione (70) under mild alkaline conditions (Scheme 8). Ugi and co-worker126,127 found that when the reaction of isonitriles and hydrazoic... 

Fully conjugated aromatic tetrazole rings have structures (1) or (2) and are numbered as shown. These are discussed in Section 4.17.5. Dihydrotetrazoles are dealt with as nonconjugated systems in Section 4.17.6. The most common forms of these are the structures (3) and (4). The A -tetrazolines (3) may give diaziridines when heated or if aromatic substituents are present at C-5 cycloreversion to azides and imines may occur <87BSF525, 88CB1213>. The 1,4-dihydrotetrazoline structure (4) is common for Y = S, O, NR and CR2. 

Substituents containing active hydrogen atoms at C-5, such as HO, HS, and RNH, can theoretically exhibit a tetrazole-tetrazoline tautomerism. It is well established <84CHEC-I(5)79l > that —OH and —SH groups exist predominantly and probably exclusively in the tetrazolin-5-one forms, for example (32) and (34). 

In the new structures of type (59) the reactive centre is the methanide site which behaves as a nucleophile. <86JCS(Pi)ii57, 92JCS(P1)1483> (Section 4.17.8). Tautomeric tetrazole-tetrazoline structures of general type (4 R = H) may show ambident reactivity with reactions occurring on the ring or the exocyclic X atom (Sections 4.17.6 and 4.17.7). 

The main types of nonconjugated tetrazoline compounds are the 1,5- and 1,4-dihydroderivatives with the general structures (3) and (4). The structure (4) also includes systems which are tautomeric with the conjugated aromatic tetrazole ring. The only known tetrahydro-tetrazolines are the compounds (5) (Section 4.17.1.1). 

Detailed studies by L abbe et al. support initial formation of 4-alkyl-5-iminothiatriazoles by addition of the azide to the C=S of the isothiocyanate. The thiatriazoline then undergoes the type of transformations outlined in Scheme 13. Tetrazoline (95) is also formed as a minor product by addition of the azide to the N=C of the isothiocyanate <75JHC607,77JOC1159>, see also <75CC24>. 

Photodecomposition of A2-1,2,3-triazolines gives aziridines. In cyclohexane the cis derivative (434) gives the cis product (435), whereas photolysis in benzene in the presence of benzophenone as sensitizer gives the same ratio of cis- and /ran.y-aziridines from both triazolines which is accounted for in terms of a triplet excited state (70AHC(il)l). A2-Tetrazolines are photolyzed to diaziridines. 

---