Influence of the diol structure on the Lewis acidity of phenylboronates

A series of cyclic esters of pentafluorophenylboronic acid have been obtained and their Lewis acidity evaluated experimentally by a modified Gutmann method. The results based on ³¹P NMR measurements were compared with those determined by quantum mechanical calculations at the DFT‐VSXC/pcS‐2 level of theory. The differences in Lewis acidity are discussed on the basis of electronic and geometric parameters. The calculations revealed that the complexes of investigated esters with Et₃PO have multiple conformers of a wide range of calculated ³¹P NMR shielding constants. Additionally, a correlation between the calculated O‐B‐O angle of esters and the experimental acceptor number was found. Copyright © 2013 John Wiley & Sons, Ltd.