An Efficient Method for Solution-Phase Parallel Synthesis of 2-Quinoxalinol Salen Schiff-Base Ligands

Abstract

A solution-phase parallel method for the synthesis of 2-quinoxalinol salen ligands was designed and optimized. The synthesis begins with commercially available 1,5-difluoro-2, 4-dinitrobenzene (DFDNB) and employs a sequence of five straightforward and high-yielding reaction steps. Simple laboratory techniques with low sensitivity to water or air for solution-phase parallel reactions were coupled with convenient workup and purification procedures to give high-purity and yield a small ligand library of 20 compounds. The final step, a Schiff-base condensation of an aldehyde with the diaminoquinoxaline results in a new category of ligands for metal coordination or of potential bioactivity, based on the skeleton 2,2'-(1E,1'E)-(quinoxaline-6,7-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)diphenol. The approach described here is easily adaptable for parallel synthesis of a larger library.

Actinide Selective Systems for Environmental Extraction and Sensing Applications

“…9 Labeling studies with 15 N and NMR to identify the asymmetric 2-quinoxolinol intermediate, and a procedure for the preparation of the asymmetric system have been described in detail elsewhere. 9 Labeling studies with 15 N and NMR to identify the asymmetric 2-quinoxolinol intermediate, and a procedure for the preparation of the asymmetric system have been described in detail elsewhere.…”

“…9 During the synthesis of this library, it was found that on reaction of the diamine with aldehyde derivatives, the singly substituted 2-quinoxalinol imines (ex. Synthetic methods with low sensitivity to water or air in solution-phase parallel reactions were coupled with convenient workup and purification procedures resulting in a small ligand library of 20 compounds (4).…”

Present status of quinoxaline motifs: Excellent pathfinders in therapeutic medicine

“…<<<<Scheme 10>>>> (e) Although, the solution-phase parallel synthesis of a series of diamino-2-quinoxalinol derivatives was previously reported [58,59]. However, Wu and Gorden had simplified further and optimized the method for the synthesis of diamino-2-quinoxalinols 34 [60] by replacing the scavenger resins used in the previous investigations with 2 equivalents of DIPEA (diisopropylethyl amine) to remove the produced HF and HCl in first step (Scheme 11). They M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 6 also successfully applied these diamino-2-quinoxalinols as precursors in solution-phase parallel method for the synthesis of 2-quinoxalinol salen ligands 35 [60].…”

Synthesis, characterization and properties of cellulose‐grafted glycine derivatives

“…These Schiff bases are all of great importance in the fields of analytical chemistry, stereochemistry, electrochemistry, spectroscopy, molecular self-assembly, supermolecular chemistry, biochemistry model systems, catalysis, materials, nuclear chemistry, and chemical disciplines. [9][10][11][12] However, primary amines or aldehydes are not present in cellulose; cellulose has to be modified to obtain the Schiff base compounds. One effective method is through the selective oxidation of dialdehyde cellulose (DAC) with the use of a further reaction with amines to produce oxidative Schiff alkali cellulose derivatives.…”