An Unusual Triazole Synthesis from Aurones

Abstract

Attempts to prepare azido-substituted aurones via a copper-catalyzed azidation failed to afford the desired product, but instead resulted in an unusual triazole formation reaction. Further efforts noted that copper was not required for this reaction, but simply thermal treatment with sodium azide in a polar aprotic solvent. A wide range of substitution patterns were tolerated in this reaction to afford the interesting salicyl-substituted triazoles in modest to excellent yield. While the mechanism is not yet clear, a simple elimination/cyclization pathway seems unlikely given the failure of the reaction on the corresponding thioaurones, which feature an even better thiol leaving group. Regardless, the potential utility of these easily accessible, multifunctional compounds should engender further interest and applications.

Unusual participation of O-propargyl group during the cyclization of 6-hydroxy-2-propargyl ethers of aryl chalcones: one-pot synthesis of 2-acyl-3-styrylbenzofuran and 7-aryldibenzo[b,d]furan-1,7-diols

“…On the other hand, dibenzofuran derivative 7a was propargylated 7 to form dipropargylated dibenzofuran product 26 . Compound 26 was further transformed to triazole compound 27 using Click reaction 14 by treatment with sodium azide, benzyl bromide, copper iodide, and Et 3 N using t -BuOH : H 2 O (1 : 3) as a solvent at RT. Also, compound 7a was allylated using allyl bromide and pentenyl bromide, which furnished diallylated dibenzofuran product 28 and dipentenylated dibenzofuran product 29 , respectively.…”

Evaluation of the Antibacterial Effect of Aurone-Derived Triazoles on Staphylococcus aureus

“…The syntheses and characterizations of the AT compounds used in this study have been previously described [ 34 , 76 ]. Purified powders of the AT compounds were solubilized in 100% dimethyl sulfoxide (DMSO) to a concentration of 10 mM.…”

“…Due to the bioactivity of these compounds, efforts to synthesize aurone-derived compounds of high concentration and purity using efficient, inexpensive, and environmentally friendly methodologies are evolving [ 32 , 33 ]. In an attempt to further diversify the aurones by synthesizing azido-substituted aurones via copper-catalyzed azidation, a new class of aurone-derived salicyl-substituted 1,2,3-triazoles was produced [ 34 ]. An aurone-derived triazole library of 42 compounds was subsequently screened for bioactivity.…”

A concise update on the synthetic transformation of aurones via asymmetric cycloaddition, annulation, and Michael/Mannich reactions

“…It is believed that, given this potential and their accessibility, they may prove to be novel, untested scaffolds for more development. 91 …”