Natural abundance nitrogen-15 nuclear magnetic resonance spectral studies on selected donors

Rao, N. Someswara; Rao, Gundu; Murthy, B.N; Das, M.; Prabhakar, T. G.; Lalitha, M

doi:10.1016/s1386-1425(02)00016-1

Cited by 17 publications

(12 citation statements)

References 46 publications

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“…The chemical shift at 103 ppm was too far downfield to be consistent with an amine moiety (35–70 ppm), and too far upfield to be consistent with an amide (110–130 ppm), but was in good agreement with reported chemical shifts for protonated amidines. 48 , 49 Furthermore, the 169 ppm chemical shift of P C N was also in line with the literature reported chemical shift of amidine carbons. 49 …”

Section: Resultssupporting

confidence: 89%

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

et al. 2015

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Section: Resultssupporting

confidence: 89%

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

et al. 2015

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“…Also, complex 5 provided a diffraction quality crystal in MeNO 2 and was submitted to X-ray analysis to provide the first reported crystallographic structure of this complex. No signal was observed, and no comparison with pyrazine 29 was possible in our attempt to perform 15 N and 1 H− 15 N HMBC NMR spectroscopy. We previously reported on the 1,4-bis-BF 3 -quinoxaline redox activity and stability and characterized the complex using the typical 1 H, 13 C, 11 B, and 19 F. 1 In this work, we wanted to provide further spectroscopic evidence of the putative structure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“… a Reference . b See ref . c Analysis was performed in CDCl 3 . 15 N ssNMR of complex 1 showed a signal at −189 ppm. d Reference . e Analysis was performed in CD 3 CN. f Pyrazine δ −42.8 ppm in CDCl 3 ; see ref . g Reference . h Quinoxaline δ is reported in CDCl 3 ; see ref . All measurements were adjusted vs MeNO 2 at 0 ppm.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Pyridine– and Pyrazine–BF₃ Complexes and Their Characterization in Solution and Solid State

Chénard¹,

Sutrisno²,

Zhu³

et al. 2016

J. Phys. Chem. C

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Following the discovery of the redox-active 1,4bis-BF 3 -quinoxaline complex, we undertook a structure− activity study with the objective to understand the active nature of the quinoxaline complex. Through systematic synthesis and characterization, we have compared complexes prepared from pyridine and pyrazine derivatives, as heterocyclic core analogues. This paper reports the structural requirements that give rise to the electrochemical features of the 1,4-bis-BF 3 -quinoxaline adduct. Using solution and solidstate NMR spectroscopy, the role of aromatic ring fusion and nitrogen incorporation in bonding and electronics was elucidated. We establish the boron atom location and its interaction with its environment from 1D and 2D solution NMR, X-ray diffraction analysis, and 11 B solid-state NMR experiments. Crystallographic analysis of single crystals helped to correlate the boron geometry with 11 B quadrupolar coupling constant (C Q ) and asymmetry parameter (η Q ), extracted from 11 B solid-state NMR spectra. Additionally, computations based on density functional theory were performed to predict electrochemical behavior of the BF 3 −heteroaromatic complexes. We then experimentally measured electrochemical potential using cyclic voltammetry and found that the redox potentials and C Q values are similarly affected by electronic changes in the complexes.

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“…The data acquisition parameters were 10 kHz spectral width, 2 kHz 2D spectral width, a one second acquisition time, one second delay time, 2 × 64 increments, and 8 repetitions. Chemical shifts were referenced to formamide (108.5 ppm) as an internal standard (12). …”

Section: Methodsmentioning

confidence: 99%

Serendipitous Discovery of α-Hydroxyalkyl Esters as β-Lactamase Substrates

Pelto

Pratt

2010

Biochemistry

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O-(1-Carboxy-1-alkyloxycarbonyl) hydroxamates were found to spontaneously decarboxylate in aqueous neutral buffer to form O-(2-hydroxyalkylcarbonyl) hydroxamates. While the former molecules do not react rapidly with serine β-lactamases, the latter are quite good substrates of representative classes A and C, but not D, enzymes, and particularly of a class C enzyme. The enzymes catalyze hydrolysis of these compounds to a mixture of the α-hydroxyacid and hydroxamate. Analogous compounds containing aryloxy leaving groups rather that hydroxamates are also substrates. Structure-activity experiments showed that the α-hydroxyl group was required for any substantial substrate activity. Although both D- and L-α-hydroxy acid derivatives were substrates, the former were preferred. The response of the class C activity to pH and to alternative nucleophiles (methanol and D-phenylalanine) suggested that the same active site functional groups participated in catalysis as for classical substrates. Molecular modeling was employed to explore how the α-hydroxy group might interact with the class C β-lactamase active site. Incorporation of the α-hydroxyalkyl moiety into novel inhibitors will be of considerable interest.

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Natural abundance nitrogen-15 nuclear magnetic resonance spectral studies on selected donors

Cited by 17 publications

References 46 publications

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

Synthesis of Pyridine– and Pyrazine–BF₃ Complexes and Their Characterization in Solution and Solid State

Serendipitous Discovery of α-Hydroxyalkyl Esters as β-Lactamase Substrates

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Natural abundance nitrogen-15 nuclear magnetic resonance spectral studies on selected donors

Cited by 17 publications

References 46 publications

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

Mechanistic investigation of aziridine aldehyde-driven peptide macrocyclization: the imidoanhydride pathway

Synthesis of Pyridine– and Pyrazine–BF3 Complexes and Their Characterization in Solution and Solid State

Serendipitous Discovery of α-Hydroxyalkyl Esters as β-Lactamase Substrates

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Synthesis of Pyridine– and Pyrazine–BF₃ Complexes and Their Characterization in Solution and Solid State