Regioselective Synthesis of Furan-Containing 1,2,3-Triazoles by Means of 1,3-Dipolar Cycloaddition of Azide to 2,3-Allenoates

A method for the synthesis of new 1,2,3-triazole heterocycles based on keto-stabilized 2,3-allenoates is presented. The effect of substituents in the starting reagents on the regio- and stereochemistry of the resulting products is studied, and the main physicochemical characteristics of the synthesized compounds are determined. In particular, it is shown that regio- and stereoselective 1,3-dipolar cycloaddition of 5-(azidomethyl)-2-furaldehyde (obtained from the chloro derivative of 5-HMF) to 2,3-dienoates (synthesized from N-substituted amino acids) in a toluene medium leads to the formation of 1,2,3-triazoles, in which the spatial arrangement of the azide substituents is characterized by the maximum distance from the ester group, which is due to the minimization of steric interactions.