1261297-52-2Relevant academic research and scientific papers
Reaction of alkynes and azides: Not triazoles through copper-acetylides but oxazoles through copper-nitrene intermediates
Haldon, Estela,Besora, Maria,Cano, Israel,Cambeiro, Xacobe C.,Pericas, Miquel A.,Maseras, Feliu,Nicasio, M. Carmen,Perez, Pedro J.
supporting information, p. 3463 - 3474 (2014/04/03)
Well-defined copper(I) complexes of composition [Tpm* ,BrCu(NCMe)]BF4 (Tpm*,Br=tris(3,5- dimethyl-4-bromo-pyrazolyl)methane) or [Tpa* Cu]PF6 (Tpa=tris(3,5-dimethyl-pyrazolylmethyl)amine) catalyze the formation of 2,5-disubstituted oxazoles from carbonyl azides and terminal alkynes in a direct manner. This process represents a novel procedure for the synthesis of this valuable heterocycle from readily available starting materials, leading exclusively to the 2,5-isomer, attesting to a completely regioselective transformation. Experimental evidence and computational studies have allowed the proposal of a reaction mechanism based on the initial formation of a copper-acyl nitrene species, in contrast to the well-known mechanism for the copper-catalyzed alkyne and azide cycloaddition reactions (CuAAC) that is triggered by the formation of a copper-acetylide complex.
Regioselective formation of 2,5-disubstituted oxazoles via copper(I)-catalyzed cycloaddition of acyl azides and 1-alkynes
Cano, Israel,Alvarez, Eleuterio,Nicasio, M. Carmen,Perez, Pedro J.
supporting information; experimental part, p. 191 - 193 (2011/03/16)
The reaction of 1-alkynes with acyl azides in the presence of [Tpm *,BrCu(NCMe)]BF4 [Tpm*,Br = tris(3,5-dimethyl-4-bromopyrazolyl)methane] as the catalyst provides 2,5-oxazoles in moderate to high yields. This is a novel transformation of the CuAAC type that constitutes a significant variation of the commonly observed [3 + 2] cycloaddition reaction to yield 1,2,3-triazoles.
