Boronate Derivatives of Functionally Diverse Catechols: Stability Studies

Kamal Aziz Ketuly,A Hamid A Hadi

doi:10.3390/molecules15042347

Abstract

Benzeneboronate of catecholic carboxyl methyl esters, N-acetyldopamine, coumarin and catechol estrogens were prepared as crystalline derivatives in high yield. Related catechol compounds with extra polar functional group(s) (OH, NH2) do not form or only partially form unstable cyclic boronate derivatives.

Highlights

The selective reactions of boronic acids with compounds containing two or more suitably disposed proximal polar functional groups (OH, NH, SH, COOH) can afford cyclic derivatives of reduced polarity, of value in analytical characterization and in separation of polyfunctional compounds [1,2].Crystalline benzeneboronates from the reactions of benzeneboronic acid with polyols [3], sugars [4,5], other carbohydrates [6,7,8], macrolide aglycones [9] and steroids [10] have been isolated and characterized
In the present work we focused on the formation and stabilities of cyclic boronate esters of various types of biologically important catechols
They were unstable on thin-layer chromatography (TLC) or on 'dry column' silica gel chromatography, undergoing disassociation with subsequent partial oxidation

Summary

Introduction

The selective reactions of boronic acids with compounds containing two or more suitably disposed proximal polar functional groups (OH, NH, SH, COOH) can afford cyclic derivatives of reduced polarity, of value in analytical characterization and in separation of polyfunctional compounds [1,2]. Molecules 2010, 15 crystallization [13]; Boronate affinity chromatography (BAC) is an important tool for specific capture and separation of cis-diol-containing compounds such as glycoproteins, RNA and carbohydrates[14]. The rigidity of the cyclic boronate derivatives of corresponding 1,2- or 1,3-diols, requiring relatively fixed conformations, is used in nuclear magnetic resonance (NMR) studies of carbohydrate concentrations and the position of their functional groups [26].

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Results and Discussion

Experimental

Conclusions