Andrew M. Kelly

Simple protocols for NMR analysis of the enantiomeric purity of chiral diols

A three-component chiral derivatization protocol for determining the enantiopurity of chiral diols by 1H NMR spectroscopic analysis is described here. The present approach involves the derivatization of 1,2- 1,3- and 1,4-diols with 2-formylphenylboronic acid and enantiopure α-methylbenzylamine. This method affords a mixture of diastereoisomeric iminoboronate esters whose ratio can be determined by integration of well-resolved diastereotopic resonances in their 1H NMR spectra, thus enabling the determination of the enantiopurity of the parent diol. The protocol as described takes less than 90 min to complete.

Simple protocols for NMR analysis of the enantiomeric purity of chiral primary amines

A simple three-component chiral derivatization protocol for determining the enantiopurity of chiral primary amines by 1H NMR spectroscopic analysis is described here. The method involves condensation of the amines with 2-formylphenylboronic acid and enantiopure 1,1′-bi-2-naphthol. This approach affords a mixture of diastereoisomeric iminoboronate esters whose ratio can be determined by the integration of well-resolved diastereotopic resonances in their 1H NMR spectra, thus enabling the enantiopurity of the parent amine to be determined easily. The protocol, as described, takes less than 90 min to complete.

Dynamic covalent self-assembled macrocycles prepared from 2-formyl-aryl-boronic acids and 1,2-amino alcohols

Reaction of 2-formyl-aryl-boronic acids with 1,2-amino alcohols results in dynamic covalent self assembly to quantitatively afford tetracyclic macrocyclic Schiff base boracycles containing bridging boron–oxygen–boron functionality.

N,N-Butyl-decamethylferrocenyl-amine reactivity at liquid | liquid interfaces: electrochemically driven anion transfer vs. pH driven proton transfer

We have developed a permethylated ferrocene redox system with a butylamine substituent for application in liquid | liquid ion sensors. The steric hindrance associated with the methyl groups results in an electrochemical system where the ferricenium derivative is chemically inert and the redox system remains chemically reversible, even for applications in aqueous or biphasic media. N,N-Butyl-decamethylferrocenyl-amine is soluble in hydrophobic organic solvents, such as 4-(3-phenylpropyl)pyridine (PPP) and N-octyl-pyrrolidone (NOP), and is employed here under “microphase” conditions, deposited in the form of microdroplets onto an electrode and immersed in aqueous buffer solutions. It is shown that under these conditions, electron transfer and proton transfer are only weakly coupled, and that anion transfer dominates the microphase redox process over the entire pH range. The corresponding biphasic Pourbaix diagram is discussed.