1,3-Dipolar cycloadditions of organic azides to ester orbenzotriazolylcarbonyl activated acetylenic amides

Abstract

Reactions of 3-lithiopropiolate 10 with isocyanates or diisocyanates gave mono-carbamoylpropiolates 11a,b and bis-carbamoylpropiolates 12a-d, in 40-76% yields. 1,3-Dipolar cycloadditions of benzyl azide (1a) and mono-acetylenes 11a,b under thermal conditions gave mono-triazoles 13a,b in 83 and 84% yields, respectively. The structure of 13a was confirmed by X-ray crystallography. Microwave induced cycloadditions of mono-azide 1a with bis-carbamoylpropiolates 12a-d furnished the bis-triazoles 14a-d. Similar reactions of 3-(azidomethyl)-3-methyloxetane (15) with mono-acetylenes 11a,b or bis-acetylenes 12a,d produced the mono- and bis-triazoles 16a,b and 17a,b, respectively. Reactions of 1,4-bis(azidomethyl)benzene (1b) with mono-acetylenes 11a,b gave the azido-triazoles 18a,b and microwave irradiation with simultaneous air-cooling gave bis-triazoles 19a,b. 1,3-Dipolar cycloaddition of benzotriazolylcarbonyl-substituted acetylene 4 and benzyl azide (1a) proceeded smoothly under microwave irradiation or thermal conditions to give the corresponding triazole 20, which on further treatment with a variety of amines gave the C-carbamoyl triazoles 21a-d in 54-91% yields.