Study of boron–nitrogen dative bonds using azetidine inversion dynamics

Hoang, Cam Thuy; Prokeš, Ivan; Clarkson, Guy J.; Tucker, James H. R.; Shipman, Michael; Walsh, Tiffany R.

doi:10.1039/c3cc36159d

Cited by 19 publications

(9 citation statements)

References 29 publications

(12 reference statements)

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“…His9 was simplified to imidazole, while the p BoF-derived chromophore to the phenyl boronic acid. Geometry optimization showed that imidazole and phenylboronic acid spontaneously combine to form a dative bond of 1.632 Å with a bonding energy ( E b ) of −11.3 kcal/mol (Figure A), in consistent with previous studies on B–N bonds . In contrast, we found that water itself cannot spontaneously form a stable B–O dative bond with phenylboronic acid.…”

Section: Resultssupporting

confidence: 91%

“…Geometry optimization showed that imidazole and phenylboronic acid spontaneously combine to form a dative bond of 1.632 Å with a bonding energy (E b ) of −11.3 kcal/mol (Figure 6A), in consistent with previous studies on B-N bonds. 56 In contrast, we found that water itself cannot spontaneously form a stable B-O dative bond with phenylboronic acid. However, in the presence of an imidazole group to polarize water, a stable B-O dative bond can form with a bond length of 1.661 Å (Figure 6B).…”

Section: Resultsmentioning

confidence: 62%

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The N–B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite

et al. 2016

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Boronic acid and esters have been extensively utilized for molecular recognition and chemical sensing. We recently reported a genetically encoded peroxynitrite (ONOO−)-specific fluorescent sensor, pnGFP, based on the incorporation of a boronic acid moiety into a circularly permuted green fluorescent protein (cpGFP) followed by directed protein evolution. Different from typical arylboronic acids and esters, the chromophore of pnGFP is unreactive to millimolar concentrations of hydrogen peroxide (H2O2). The focus of this study is to explore the mechanism for the observed unusual chemoselectivity of pnGFP toward peroxynitrite over hydrogen peroxide by using site-directed mutagenesis, X-ray crystallography, 11B NMR, and computational analysis. Our data collectively support that a His residue on the protein scaffold polarizes a water molecule to induce the formation of an sp3-hybridized boron in the chromophore, thereby tuning the reactivity of pnGFP with various reactive oxygen and nitrogen species (ROS/RNS). Our study demonstrates the first example of tunable boron chemistry in a folded nonnative protein, which offers wide implications in designing selective chemical probes.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 62%

The N–B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite

et al. 2016

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“…15 This observation is consistent with the in situ dynamics reported previously for Wulff-type boronic acids, where a dative 1,5-N→B interaction participates in reversible association. 1,b,16 …”

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confidence: 99%

“…This trend is consistent with increasing sp 3 character at boron, likely resulting from a stronger, more covalent N→B interaction. 14,16a …”

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confidence: 99%

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

Harlow

Zakharov

et al. 2013

Organometallics

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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.

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“…The variability of the diastereomeric ratio in complexes 2 and 3 could be explained taking into consideration two factors, namely: (a) the role of the ethereal solvent and (b) the azetidine’s nitrogen inversion. In fact, as reported in Figure , it is likely that the solvent could take up BH 3 from the azetidine nitrogen, and the temperature, as well as the nature of the R group and nitrogen’s stereochemistry, could affect this equilibrium . Additionally, the nitrogen dynamics in free azetidines 1 must be taken into consideration.…”

Section: Results and Discussionmentioning

confidence: 97%

Azetidine–Borane Complexes: Synthesis, Reactivity, and Stereoselective Functionalization

et al. 2018

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The present study reports, for the first time, the synthesis and structural features of azetidine-borane complexes, as well as their reactivity in lithiation reactions. A temperature-dependent stereoselectivity has been disclosed in the reaction of borane with N-alkyl-2-arylazetidines, allowing for a stereoselective preparation of azetidine-borane complexes 2 and 3. A regioselective hydrogen/lithium permutation, at the benzylic position, was observed in lithiation reactions of complexes possessing a syn relationship, between the ring proton and the BH group. In contrast, scarce or no reactivity was noticed in complexes lacking such a stereochemical requirement. The configurational stability of the lithiated intermediates has also been investigated, in order to shed some light on the stereoselectivity of the lithiation/electrophile trapping sequence. Calculations helped in supporting experimental observations, concerning structure and reactivity of these azetidine-borane complexes. Data suggest that the BH group could promote the lithiation reaction likely by an electrostatic complex induced proximity effect. Interestingly, a new synthetic strategy for the synthesis of N-alkyl-2,2-disubstituted azetidines has been developed.

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Study of boron–nitrogen dative bonds using azetidine inversion dynamics

Cited by 19 publications

References 29 publications

The N–B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite

The N–B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite

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

Azetidine–Borane Complexes: Synthesis, Reactivity, and Stereoselective Functionalization

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