Benzotriazole aroylation

Benzotriazole has been prepared directly by the action of nitrous acid on 0-phenylenediamine1 and by the hydrolysis of an acylated or aroylated benzotriazole which has been previously prepared by the action of nitrous acid on the corresponding mono acylated or aroylated 0-phenylenediamine.2 3 4-i The above procedure is the direct method and gives better over-all yields than the methods involving several intermediate steps. Most methods described in the literature employ mineral acid. Acetic acid is much more satisfactory. 

The isomerization between N- and (9-acylated benzotriazol-l-ols and 1,2,3-triazol-l-ols has been extensively studied (see Section 4.01.7.1) in part by x-ray methods. The aroyl group position is established by x-ray crystallographic analyses because the N- and (9-acylated forms are not readily distinguished by spectral methods. X-ray analyses of l-(4-nitrobenzoyloxy)-1,2,3-triazole (19a) <93AX(C)49>, l-(4-chlorobenzoyloxy)-l,2,3-triazole (19b) <88AX(C)1063>, and 1-benzoyloxy-... 

Zinc chloride-doped natural phosphate was shown to have catalytic behavior in the 1,3-dipolar cycloadditions of nucleoside acetylenes with azides to form triazolonucleosides <99SC1057>. A soluble polymer-supported 1,3-dipolar cycloaddition of carbohydrate-derived 1,2,3-triazoles has been reported <99H(51)1807>. 2-Styrylchromones and sodium azide were employed in the synthesis of 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles <99H(51)481>. Lead(IV) acetate oxidation of mixed bis-aroyl hydrazones of biacetyl led to l-(a-aroyloxyarylideneamino)-3,5-dimethyl-l,2,3-triazoles <99H(51)599>. Reaction of 1-amino-3-methylbenzimidazolium chloride with lead(fV) acetate afforded l-methyl-l/f-benzotriazole <99BML961>. Hydrogenation reactions of some [l,2,3]triazolo[l,5-a]pyridines, [l,2,3]triazolo[l,5-a]quinolines, and [l,2,3]triazolo[l,5-a]isoquinolines were studied <99T12881>. 

A-Aroyl-benzotriazoles react well with indolyl anions to give A-aroyl-indoles. "" A-Acylation " and A-arylsulfonylation "" can also be achieved efficiently using phase-transfer methodology. 

Enamines (57) were prepared via intermediates (56) in moderate to excellent yields by the reaction of acyl or aroyl benzotriazoles (e.g., 54) with ketimines (e.g., 55) in the presence oflithium diethylamide (Scheme 15) (2000S2029). 

The thermal decomposition of acyl azides into isocyanate intermediates is known as Curtius rearrangement reaction (Scheme 5.2) [27, 28]. Conventionally used general methods to synthesize aroyl azides are limited to diazotization of hydrazides and reactions of NaNs with acid chlorides, mixed anhydrides, and Al-acyl benzotriazoles [35-38]. However, these procedures involve highly reactive chemicals which put significant limitations on functionalities of the substrate. The development of methodologically new, highly functional-group tolerant, catalytic routes to aroyl azides is particularly desirable. 

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