Benzotriazole chemistry

The Generation and Reactions of Non-stabilized a-Aminocarbanions <1998T2647> - includes significant amount of benzotriazole chemistry ... 

During extensive studies, the Katritzky group utilized benzotriazole chemistry as an azomethine yhde synthetic equivalent. Initial studies, with the simple bis substituted hydroxylamine (51) had furnished a wide range of cycloadducts, from... 

NATIVE CHEMICAL LIGATION USING BENZOTRIAZOLE CHEMISTRY... 

Upon treatment with n-butyllithium at — 78 °C, 1-methylbenzotriazole 380 is lithiated on the methyl group to give l-(lithiomethyl)benzotriazole 381. Rapid addition of a carboxylic ester to the solution provides a-(benzotriazol-l-yl)alkyl ketone 382 in high yield (Scheme 61) <1997JOC4142>. This easy access to ketones 382 and their reactivity makes them valuable intermediates in several syntheses. Their chemistry is discussed separately in Section 5.01.8.4. 

For clarity, in the following schemes of this subsection, the benzotriazol-2-yl stmctures are often omitted when such derivatives are present in the reaction mixtures, and their chemistry is not different from that of the benzo-triazol-l-yl derivatives. When there is a clear distinction in chemistry, the benzotriazol-2-yl isomers are treated separately. 

To get a complex set of substituents by direct derivatization of benzotriazole is not feasible. In such situations, it is better to have all the substituents in place first and later construct the heterocyclic ring. High reactivity of anilines and their well-developed chemistry makes them good stating materials. In an example shown in Scheme 215, acetanilide 1288 is nitrated to afford nitro derivative 1289 in 73% yield. Catalytic reduction of the nitro group provides methyl 4-acetylamino-3-amino-5-chloro-2-methoxybenzoate 1290 in 96% yield. Nitrosation of compound 1290 in diluted sulfuric acid leads to intermediate 1291, which without separation is heated to be converted to 7-chloro-4-methoxy-l//-benzotriazole-5-carboxylic acid 1292, isolated in 64% yield <2002CPB941>. 

Major advancements in the chemistry of pyrazoles, imidazoles, triazoles, tetrazoles, and related fused heterocyclic derivatives continued in 2000. Solid-phase combinatorial chemistry of pyrazoles and benzimidazoles has been particularly active. Synthetic routes to all areas continue to be pursued vigorously with improvements and applications. Notably, metal-promoted and cross-coupling reactions of all classes seemed to be a dominant theme in 2000. Applications of pyrazole-, imidazole-, and 1,2,3-benzotriazole-containing reagents to a wide array of synthetic applications remained active. 

Materials. The structures of various o-hydroxyphenyl-benzotriazoles which have been studied extensively by our reseach group are shown in Figure 2. Each of these compounds was synthesized, purified and supplied by Dr. B. Milligan and Mr. P. J. Waters of the CSIRO Division of Protein Chemistry. The derivative 2-(2 -methyl-5 -methoxyphenyl)benzotriazole (MeTIN) was supplied by Dr. R. G. Amiet of the Royal Melbourne Institute of Technology. 

The present review, which surveys the literature to mid-1972, has been restricted to monocyclic 1,2,3-triazoles, since much of the chemistry of benzotriazoles and other fused systems has little in common with monocyclic triazole chemistry. The aim has been to give a broad survey of methods of synthesis and reactions of triazoles few references are included from before 1960, as these are available from earlier reviews. 

A similar chemistry to that described for (substituted) pyridine rhenium(V) oxo complexes is also observed for other heterocyclic nitrogen donor ligands such as pyrimidine, pyrazine, substituted imidazoles, benzimidazoles, or benzotriazole. ... 

Triazoles and benzotriazoles are of great importance in organic synthesis, medicinal chemistry, and industry. Numerous publications have appeared in the decade from 1985-1995. 

There is a growing interest in the use of 15N NMR spectroscopy for elucidation of various structural problems of azole chemistry, especially tautomerism. For example, the mole fractions of the prototropic tautomers were obtained from the 15N chemical shifts of the NH tautomers and the corresponding N-methyl derivatives. By this method, the average mole fraction for the 2-NH tautomer of benzotriazole is 0.02 in both CDC13 and DMSO, and that of 1,2,3-triazole is 0.34 in CDC13 and 0.55 in DMSO (82JOC5132). 

This section covers ligands containing the 1,2,3-triazole ring system. These include, in addition to the parent triazole, various N- and/or C-substituted triazoles, benzotri azole, and a number of 8-azapurines. The coordination chemistry of 5-thio-l,2,3,4-thiatriazole is selectively reviewed. All of these molecules, with the exception of the N-substituted triazoles, are capable of coordinating in anionic as well as neutral form. 1,2,3-Triazole, first prepared by von Pechmann in 1888 (215), is a weak acid (p/ a = 9.26) (88) and exists as a mixture of the tautomeric forms (structures la and lb). Benzotriazole (2), first correctly formulated... 

Benzotriazoles, for example, are accessible from o-aminoaryl-substituted triazenes after a two-step reaction sequence a nucleophilic displacement followed by cleavage/heterocyclization.35 The nucleophilic halide displacement of activated haloarenes is an indispensable tool for the synthesis of highly substituted arenes. Fluoronitroarenes in particular have served as excellent precursors in this transformation. Thus, it was appealing to combine this SNAr reaction with the flexibility of diazonium chemistry. In this case, an immobilized fluoronitrophenyl triazene would be the equivalent of the Sanger reagent. 

While there are substantial differences between the chemistry of benzotriazoles and triazolo-pyridines, the systems also have some similar reactivity profiles. As shown in Scheme 9, reductive... 

Some data on the application of nitroazole derivatives have been mentioned in reviews and monographs on the chemistry of nitroazoles [1], pyrazoles [2], furox-ans [3], benzimidazole [4], and benzotriazole [5, 6], etc. Special monographs and reviews have been devoted to biological and clinical application of different nitroimidazoles [7-23] and chemotherapy of metronidazole [24], Therefore, it is not given much attention to metronidazole here. 

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