Acetylenes, reaction with trimethylsilyl azide

Unlike hydrazoic acid, trimethylsilyl azide is thermally quite stable. Even at 200° it decomposes slowly and without explosive violence. Accordingly it is a very convenient and safe substitute for hydrazoic acid in many reactions. A notable example is the cycloaddition of hydrazoic acid to acetylenes which is a general route to substituted triazoles.4 The reaction of trimethylsilyl azide with acetylenes is also a general reaction from which the 2-trimethyIsilyI-1,2,3-triazoles may be obtained in good yield.5 On hydrolysis these adducts are converted under mild conditions to the parent alkyl 1,2,3-triazoles.5... 

Iridium dimer complexes catalyse the 3 + 2-cycloaddition reactions of organic azides with bromoalkynes to furnish 1,5-disubstituted 4-bromo-1,2,3-triazoles in excellent yields under mild conditions. Ruthenium(II)-azido complexes undergo 3 + 2-cycloaddition reactions with strained cyclooctynes under ambient temperatures. No reaction was observed with non-activated terminal or internal alkynes under the same conditions. Dithioic acid copper catalysts (60) catalyse the 3 + 2-cycloaddition reaction of azides with alkynes to form 1,4-disubstituted-1,2,3-triazoles in various solvents and under various temperatures. Thermal Huisgen 3 + 2-cycloaddition reactions of azides and bis(trimethylsilyl)acetylene formed 4,5-bis(trimethylsilyl)-l/f-l,2,3-triazoles in low to high yields (15-95%). The Cu(I)-catalysed 3 + 2-cycloaddition... 

Reactions of salts of 1,2,3-triazole with electrophiles provide an easy access to 1,2,3-triazol-jV-yl derivatives although, usually mixtures of N-l and N-2 substituted triazoles are obtained that have to be separated (see Section 5.01.5). Another simple method for synthesis of such derivatives is addition of 1,2,3-triazole to carbon-carbon multiple bonds (Section 5.01.5). N-l Substituted 1,2,3-triazoles can be selectively prepared by 1,3-dipolar cycloaddition of acetylene or (trimethylsilyl)acetylene to alkyl or aryl azides (Section 5.01.9). 

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