Tandem, copper-catalyzed monodesilylation/CuAAC reactions of 1,4-bis(trimethylsilyl)-1,3-butadiyne and azides for the preparation of 4-(TMS-ethynyl)-1,2,3-triazoles

A tandem copper-catalyzed 1,4-bis(trimethylsilyl)-1,3-butadiyne (BTMSBD) monodesilylation/azide CuAAC reaction has been developed for the efficient synthesis of 1-substituted-4-(TMS-ethynyl)-1,2,3-triazoles. The one-pot, two-step process, which offers yields of up to 73%, is performed by treating a mixture of BTMSBD and an azide in DMF with a catalytic quantity of a copper(I) salt and a stoichiometric amount of an organic base. Minor byproducts including 4-ethynyl-1,2,3-triazoles and bis(4,4'-1,2,3-triazoles) are also generated in this process. The reaction exhibits broad functional group tolerance, accommodating both aryl and alkyl azides. To illustrate the overall utility of the new method, the 4-(TMS-ethynyl)-1,2,3-triazole products were subjected to a diverse variety of modification processes, which led to the generation of an array of functionalized 4-alkynyl- and bis-1,2,3-triazole derivatives.