53690-21-4Relevant academic research and scientific papers
Stability of boronic esters - Structural effects on the relative rates of transesterification of 2-(phenyl)-1,3,2-dioxaborolane
Roy, Chandra D.,Brown, Herbert C.
, p. 784 - 790 (2007/10/03)
Relative rates of reaction of the achiral cyclic phenylboronic ester 2-(phenyl)-1,3,2-dioxaborolane with a wide variety of structurally modified diols, have been studied to understand the factors influencing the relative stabilities of boronic esters. It is found that the alkyl substituents on the α-carbons of diols slow down the transesterification, but produce thermodynamically more stable boronic ester. Six-membered boronic esters are thermodynamically more stable than their corresponding five-membered analogs. Amongst cyclic 1,2-diols, cis-1,2-cyclopentanediol displaces ethylene glycol instantaneously whereas trans-1,2-cyclopentanediol is totally unreactive, which suggests that the cis-stereochemistry of the 1,2-diol is a prerequisite for transesterification. Among the 1,5-diols, diethanolamine displaces ethylene glycol quite rapidly forming a more stable bicyclic chelate in which nitrogen is attached to boron by a coordinating bond (as evident by 11B NMR spectroscopy). The oxygen atom of di(ethylene glycol) and the sulfur atom of 2,2′-thiodiethanol do not assist in displacing the ethylene glycol from their boronic esters.
The structure of the benzeneboronate of pentane-1,3,5-triol
Bourne, Edward J.,Mckinley, Ian R.,Weigel, Helmut
, p. 141 - 149 (2007/10/16)
The relative ease of formation of five-, six-, seven-, and eight-membered cyclic benzeneboronates is discussed. Pentane-1,3,5-triol forms, by interaction with benzene-boronic anhydride, exclusively DL-4-(2-hydroxyethyl)-2-phenyl-1,3,2-dioxaborinane. It is suggested that, in this compound, the oxygen atom of the hydroxyl group is intramolecularly co-ordinated with the boron atom.
