Benzyl triazoles from

Meng and Kung [18] also exploited a robust, regioselective synthetic approach to 3-amino-l,2,4-triazoles from commercially available carbonic acid benzyl ester 4-nitrophenyl ester (vi). 

Day s recent publication of a facile synthesis of 4-amino-1,2,3-triazole-5-carboxamide (73a) and its 3-benzyl derivative (from cyanoacetamide and benzyl azide). ... 

Triazoles can also be prepared from in situ formation of azides from halo compormds. For example, 1,4-disubstituted-1,2,3-triazoles 138 were obtained in excellent yields by a convenient one-pot procedure from a variety of aryl and alkyl iodides 136 and terminal alkynes 137 without isolation of potentially unstable organic azide intermediates 05SL2941>. Efficient one-pot synthesis of 1,2,3-triazoles from in situ formation of azides from benzyl and alkyl halides with alkynes has also been reported <05SL943>. 

Kacprzak, K., Efficient one-pot synthesis of 1,2,3-triazoles from benzyl and alkyl halides, Synlett, 2005, 943 946. 

In a 1-substituted 1,2,3-triazole (79), both the 2- and 3-nitrogen atoms possess lone pairs of electrons that are available for quaternary salt formation, and quatemization is known to occur at the 3-nitrogen atom to give the symmetrical cation (80). Thus, the reaction between 1-methyl-l,2,3-triazole and benzyl iodide yields the same salt as is obtained from the interaction of 1-benzyl-1,2,3-triazole and methyl iodide the salt must therefore be 80 (R = Me, R = PhCH2,... 

Spickett and Wright investigated the reactions of 4-substituted 3-amino-1,2,4-triazoles and EMME in acetic acid for 24-48 hr [67JCS(C)503]. Generally, they obtained [l,2,4]triazolo[l,5-a]pyrimidine-7-ones (1124) in 38-56% yields. In the case of the benzyl derivative (R = CH2Ph), the isomeric triazolo[l, 5-a]pyrimidin-5-one (1125) was also isolated from the mother liquor, in 5% yield. From the 4-ethyl and 4-phenethyl derivatives (R = Et, CH2CH2Ph), l-(l,2,4-triazol-3-yl)pyridin-2-ones (1126) were also obtained in 1-2% yields. 

Relatively few additions of the lower molecular weight alkyl azides have been performed, mainly because of their volatility and thermal sensitivity simple alkyltriazoles are normally obtained by alkylation of the w-triazoles. On the other hand, a very wide range of less volatile substituted alkyl azides has been added to acetylenes Their addition to acetylenic esters usually proceeds readily and provides a useful method of characterizing the azides. Benzyl azide has often been used because it is relatively stable (up to 150°), it is readily prepared, and the benzyl group can be removed from the resulting triazoles (Section IV, E). 

Substituted 1,2,4-triazoles have received less attention than their isomeric counterparts, but those results that are available indicate that their lithio derivatives are less stable than their 1-substituted isomers. Thus, in addition to undergoing the expected a-lithiation and reaction at the 5-position, 3-phenyl-4-benzyl-1.2.4-triazole also gave products resulting from ring-opening, even at -78°C (Scheme 65) (86JHC1257). 

Heterocycles containing an NH group, such as pyrroles, indoles, imidazoles, triazoles, etc., can be linked to insoluble supports as N-alkyl, N-aryl, or N-acyl derivatives (Table 3.29). The optimal choice depends mainly on the NH acidity of the heterocycle in question. Increasing acidity will facilitate the acidolytic cleavage of N-benzyl groups and the nucleophilic cleavage of /V-acyl groups from these heterocycles. 

Only the 1-benzyl-vic-triazole, crysts(from eth at 20°), mp 61°, appears to have been prepd and reported in the literature. Curtius Raschig(Ref 2) prepd 1-benzyl-vic-triazole by the reaction of benzyl azide with the methyl ester of acetylene-dicarboxylic acid, followed by sapon and decarboxylation. Wiley et al(Ref 3) prepd the compd directly and in better yield from acetylenedicar-boxylic acid, followed by decarboxylation to 1 -benzyl-vic-triaZole(77% yield)... 

Methyl ketones lead to different triazoles, depending on the azide and ketone employed (Scheme 135).2 5 s Reaction of benzyl azide with acetone and acetophenone yields mostly one or both of the triazoles derived from 38 and 39 in Scheme 64. Methyl t-butyl ketone gives, in addition, a 4-triazenyl-... 

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