Saccharide-accelerated hydrolysis of boronic acid imines
作者:James H. Hartley、Marcus D. Phillips、Tony D. James
DOI:10.1039/b202793c
日期:2002.8.22
Twenty substituted N-benzylidineaniline derivatives have been synthesised and their kinetic behaviour investigated. The rate of hydrolysis of the boronic acid imines was found to be accelerated by added saccharide. Catalytic activity was only observed below the pKa of the boronic acid. Altering the concentration or type of saccharide revealed a Brønsted-like linear free energy relationship, indicating that intramolecular general acid catalysis was operating. Structure–activity relationship studies demonstrated that the system's electronic demands were independent of the boronic acid moiety.
A number of unanswered questions occurred to us upon reading a communication by Yam and Kai (ref. ) which had reported optical sensing properties of a boronic-acid-appended ReI complex for saccharides. Careful re-examination has disclosed that the pKa-value proposed by them (5.9) is wrong and that the saccharide-binding mode at pH above the pKa is totally different from that at pH below the pKa. The absorption spectral change, which reflects an sp2-to-sp3 boron hybridisation change induced by the saccharide complexation, was observed only at pH below the pKa, and the CD band, which reflects the formation of 1∶1 cyclic complexes, appeared only at pH above the pKa. The results imply that the optimum pH should be carefully selected for the precise optical sensing of saccharides.
Nickel-catalysed addition of organoboronates to 1,3-dienesElectronic supplementary information (ESI) available: 1H NMR spectra and MS data. See http://www.rsc.org/suppdata/cc/b2/b207185a/
Aryl- and alkenylboronates were found to add to 1,3-dienes in the presence of a catalytic amount of bis(1,5-cyclooctadiene)nickel, where a proton source in combination with a solvent considerably controls the regioselectivity.
Saccharide accelerated hydrolysis of boronic acid imines
作者:James H. Hartley、Tony D. James
DOI:10.1016/s0040-4039(99)00225-7
日期:1999.3
Saccharides accelerate the rate of hydrolysis of imines 1 and 2 at pH 7.77. In contrast, the rate of hydrolysis of imine 3 is unaffected by added saccharides. (C) 1999 Elsevier Science Ltd. All rights reserved.
Fluorescence-responsive H<sub>2</sub>PO<sub>4</sub><sup>−</sup>Receptor Based on Macrocyclic Boron Complex
作者:Naohiro Kameta、Kazuhisa Hiratani
DOI:10.1246/cl.2006.536
日期:2006.5
Macrocyclic boron complex showed selective fluorescence response toward H2PO4− via hydrogen-bond network, Lewis acid–base interaction, and inhibition of PET.