Influence of fluorine substituents on the properties of phenylboronic compounds

Abstract

Rapid development of research on the chemistry of boronic acids is connected with their applications in organic synthesis, analytical chemistry, materials’ chemistry, biology and medicine. In many applications Lewis acidity of boron atoms plays an important role. Special group of arylboronic acids are fluoro-substituted compounds, in which the electron withdrawing character of fluorine atoms influences their properties. The present paper deals with fluoro-substituted boronic acids and their derivatives: esters, benzoxaboroles and boroxines. Properties of these compounds, i.e. acidity, hydrolytic stability, structures in crystals and in solution as well as spectroscopic properties are discussed. In the next part examples of important applications are given.

Synthesis, Properties and Antimicrobial Activity of 5-Trifluoromethyl-2-formylphenylboronic Acid

“…However, the correlation signal is still present in the 1 H-1 H COSY spectrum of the most concentrated sample studied (0.02 M, see Supplementary Materials for picture). The 1-1a equilibrium was investigated by 1 H NMR and 19 F NMR spectroscopy at 25 • C. The ratio of isomers was determined by integration of characteristic and well isolated signals corresponding to each of the isomers (Table 4). Four solutions differing by concentration have been prepared in DMSO (2.3 mg, 11.1 mg, 27.2 mg and 29.7 mg of 1 in 0.5 mL DMSO was dissolved) and four solutions in acetone (2.4 mg, 10.1 mg, 21.1 and 29.3 mg of 1 in 0.5 mL acetone was dissolved).…”

“…Boronic acids and especially arylboronic acids are of significant importance in chemistry. There are many examples of application of arylboronic acids, among others: building blocks in organic chemistry, sensors and receptors, polymers, active ingredients of drugs, functionalization of nanoparticles, boron neutron capture therapy (BNCT) and positron emission tomography (PET) [1][2][3][4][5]. Formyl-substituted phenylboronic acids additionally display high synthetic utility due to presence of a reactive aldehyde group.…”

“…1 H/19 F NMR Shift of the Cyclic Form (1a)1 H/ 19 F NMR Shift of The Opened Form (1)* Due to very low solubility of 1 in D 2 O the spectrum is of a relatively low signal to noise ratio.…”

(Trifluoromethoxy)Phenylboronic Acids: Structures, Properties, and Antibacterial Activity

“…Fluorinated arylboronic acids constitute an important group of compounds with a wide range of applications [ 1 ]. The introduction of a fluorine atom directly to the aromatic ring or to its substituents usually increases the Lewis acidity of these compounds, which is important in terms of their applications as well as stability [ 2 ].…”

Saturation Transfer Difference NMR Spectroscopy Using Glycopolymers

“…The peak at 4.79 ppm in the reference spectrum corresponds to HOD.The binding strength of PBA-carbohydrate interactions is dependent on the pKa of the PBAs, where lower pKa values have greater binding affinities to diols than those with higher pKa values 37,38. The PBAs 4-fluorophenylboronic acid (4-FPBA, pKa = 8.77) and 4methoxyphenylboronic acid (4-MPBA, pKa = 9.30), both have higher pKa values than 3,5-DFPBA (7.08), and should both bind to Gal90 with lower affinity than 3,5-DFBPA 39,40. Consequently, the former should exhibit lower STD-AF values than 3,5-DFPBA, while 4-MPBA would exhibit the smallest STD-AF values.…”