BN/CC isosteric compounds as enzyme inhibitors: N- and B-ethyl-1,2-azaborine inhibit ethylbenzene hydroxylation as nonconvertible substrate analogues.

Good substrate gone bad! BN/CC isosterism of ethylbenzene leads to N-ethyl-1,2-azaborine and B-ethyl-1,2-azaborine. In contrast to ethylbenzene, which is the substrate for ethylbenzene dehydrogenase (EbDH), N-ethyl-1,2-azaborine (see scheme; Fc=Ferricenium tetrafluoroborate) and B-ethyl-1,2-azaborine are strong inhibitors of EbDH. Thus, the changes provided by BN/CC isosterism can lead to new biochemical reactivity.

Thermodynamically Controlled, Dynamic Binding of Diols to a 1,2-BN Cyclohexane Derivative.

The reversible covalent binding of diols to an N-Bn 1,2-BN cyclohexane has been studied by 11B and 1H NMR spectroscopy and single-crystal X-ray diffraction analysis. The activation barrier for the reversible B-N Lewis acid-base interaction has been measured by variable-temperature NMR with bound (2R,3R)-(-)-2,3-butanediol (Tc = -40 °C, ΔG‡ = 11.2 ± 0.2 kcal mol-1). Deuterium labeling experiments demonstrate that ligand exchange is reversible and rapid at room temperature, and competitive binding studies establish diol association as a thermodynamically controlled process.