3-Substituted 1,2,3-triazole 1-oxides production

No mass spectra of 1,2,3-triazoles were described prior to 1968, when a series of highly substituted triazoles, the oxidation products of 1,2-dicarbonyl-bis-benzoylhydrazones, were investigated. The previously assigned structure of a dihydro-1,2,3,4-tetrazine could be excluded in favor of the 1,2,3-triazole-isoimide (52), which showed a low intensity molecular ion Mt, but a prominent [M-28] ion corresponding to loss of N2 giving (53) (68TL231). The [Af-28] ion underwent further fragmentations as shown in Scheme 1. 

Lithium 1,2,4-triazolate with [Rh2( j,-Ph2PCH2PPh2)(CO)2( j.-Cl)]PFj. gives the A-framed complex 177 (L=L = CO) (86IC4597). With one equivalent of terf-butyl isocyanide, substitution of one carbon monoxide ligand takes place to yield 177 (L = CO, L = r-BuNC), whereas two equivalents of rerr-butyl isocyanide lead to the product of complete substitution, 177 (L = L = r-BuNC). The starting complex (L = L = CO) oxidatively adds molecular iodine to give the rhodium(II)-rhodium(II) cationic species 178. 

Reduction of the 1//-1,2-benzodiazepines 6 with lithium aluminum hydride results in the dihydro compounds 8, which are dehydrogenated to the 3H-1,2-benzodiazepines 9 by 4-phenyl-4//-l,2,4-triazole-3,5-dione.123 The products readily revert to the 1//-tautomers in the presence of sodium methoxide. 3//-1,2-Benzodiazepines react with 3-chloroperoxybenzoic acid to give mixtures of 1- and 2-oxides, 10 and 11, in which the latter predominate. Treatment of the 2-oxides 11 with nucleophiles provides 3-substituted H- 1.2-benzodiazepines 12. Selected examples are given.124... 

Substitution of the 4-nitro group in 3,4-dinitrofuroxan 1176 by ammonia occurs readily, even at low temperature. Subsequent treatment of the obtained amine, product 1177, with r-butylamine results in formation of 4-amino-2-(/-butyl)-5-nitro-l,2,3-triazole 1-oxide 1178. However, there must be some additional side products in the reaction mixture, as the isolated yield of compound 1178 is only 17%. Upon treatment with trifluoroperacetic acid, the r-butyl group is removed. The obtained triazole system can exist in two tautomeric forms, 1179 and 1180 however, the 1-oxide form 1179 is strongly favored (Scheme 195) <2003CHE608>. 

Oxidation of a thiomethyl group in indolo azepines to a sulfoxide and a sulfone has been reported (2004AP486). Thione 415 with a variety of hydrazides 416 under thermal conditions (n-butanol, reflux) gives fused triazoles 417 in moderate to good yields as the products of a substitution/cyclization sequence (Scheme 87, Section 5.2.1.3 (1993LA1141)). 

In C5 unsubstituted 2-methyl or 2-phenyl-l,2,3-triazole 1-oxides the intermediates 400 and 403 react at C5. A methyl group at C4 does not significantly influence product composition. The chloro analogue 380 is formed in minor amounts and is easy to remove. The reaction gives access to substituted acetoxy-l,2,3-triazoles 405 and 406. 

While 5-chloro-l,2,3-triazole 1-oxide 467 reacted with sodium methox-ide with replacement of the chlorine (see Section 4.1.6.8), the corresponding bromo compound 468 under similar conditions afforded the cme-substitution product 483 as the main product (1987ACSA(B)724). A mechanism involving halogen dance and supported by control experiments is sketched in Scheme 142. The bromine in 468 is located at the less activated position with respect to nucleophilic displacement. On the other... 

In aryl- or amino-substituted 1,2,4-triazols the nitro group enters the side chain [269-271], An attempt to realize the nitration of 3,5-bisphenylamino-l,2,4-triazole led to opening of the triazole ring. Picrylurea was isolated as the only reaction product [272], The nitration products of 2-methyl-l,2,3-triazole 1-oxide under mild conditions (20°C) are a mixture of 5-nitro (75%) and 4-nitro (23%) derivatives. Under more... 

Anodic oxidation of, e.g., 1,4-dimethoxybenzene in an undivided cell containing a tetra-zole or triazole derivative together with the corresponding anion leads to the formation of the substituted product, presumably through the mechanism shown in Eq. (61) [213]. 

N-Substituted 3)5-acetoxy-6/ -amino-5a-androstanes bearing histidine and related imidazole and triazole derivatives have been prepared. Allylic oxidation with selenium dioxide of 3a- and 3)8-dimethylamino-5-enes, c.g. (498) and similar steroids, gave 4/ -hydroxy-5-ene and the allylic rearrangement product... 

The mechanism of the RuAAC reaction has been investigated by several groups and is summarized in Scheme 9.6. The proposed catalytic cycle includes the formation of the catalytically active species [Cp RuCl] and the formal substitution of the spectator ligands by the alkyne 40 and the azide 41 to give complex 42. After oxidative coupling of the alkyne and the azide, the intermediate species 43 undergoes reductive elimination and releases the aromatic triazole product 45. 

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