Results 131 to 140 of about 1,595,142 (164)

Asymmetric Synthesis and Application of Homologous Pyrroline‐2‐alkylboronic Acids: Identification of the B–N Distance for Eliciting Bifunctional Catalysis of an Asymmetric Aldol Reaction.

Asian Journal of Organic Chemistry, 2013
AbstractHomoboroproline has been shown to be an efficient bifunctional catalyst for the aldol reaction of acetone with p‐nitrobenzaldehyde by using in situ Lewis acid tuning of the boronic acid esterification with a diol. Herein, asymmetric syntheses of homologues of this catalyst are developed to compare their catalytic capability and chemical ...
Batsanov, A. S., Georgiou, I., Girling, P. R., Pommier, L., Shen, H. C., Whiting, A.   +5 more
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B−N Distance Potential of CH₃CN−BF₃ Revisited:  Resolving the Experiment−Theory Structure Discrepancy and Modeling the Effects of Low-Dielectric Environments

The Journal of Physical Chemistry B, 2007
We have re-examined the B-N distance potential of CH3CN-BF3 using MP2, DFT, and high-accuracy multicoefficient methods (MCG3 and MC-QCISD). In addition, we have solved a 1-D Schrödinger equation for nuclear motion along the B-N stretching coordinate, thereby obtaining vibrational energy levels, wave functions, and vibrationally averaged B-N distances ...
James A, Phillips, Christopher J, Cramer
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ChemInform Abstract: Asymmetric Synthesis and Application of Homologous Pyrroline‐2‐alkylboronic Acids: Identification of the B—N Distance for Eliciting Bifunctional Catalysis of an Asymmetric Aldol Reaction.

ChemInform, 2014
AbstractThe influence of the chain length in homoboroproline homologues on their catalytic activity in aldol reactions is examined.
Andrei S. Batsanov, Irene Georgiou, P. Ricardo Girling, Laure Pommier, Hong C. Shen, Andrew Whiting   +5 more
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Scalar Coupling between the ¹⁵N Centres in Methylated 1,8‐Diaminonaphthalenes and 1,6‐Diazacyclodecane: To What Extent is ^2HJ_NN a Reliable Indicator of NN Distance?

Chemistry – A European Journal, 2003
AbstractThe scalar couplings between hydrogen bonded nitrogen centres (2HJNN) in the free‐base and protonated forms of the complete series of [15N2]‐N‐methylated 1,8‐diamino naphthalenes in [D7]DMF solution have been determined, either directly (15N{1H} NMR), or, indirectly (13C{1H} NMR and simulation of the X part of the ABX spectrum (X=13C, A,B=15N)).
Lloyd-Jones, GC, Harvey, JN, Hodgson, P, Murray, M, Woodward, RL   +4 more
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Frequency Selective Heteronuclear Dipolar Recoupling in Rotating Solids:  Accurate¹³C−¹⁵N Distance Measurements in Uniformly¹³C,¹⁵N-labeled Peptides

Journal of the American Chemical Society, 2001
We describe a magic-angle spinning NMR experiment for selective (13)C-(15)N distance measurements in uniformly (13)C,(15)N-labeled solids, where multiple (13)C-(15)N and (13)C-(13)C interactions complicate the accurate measurement of structurally interesting, weak (13)C-(15)N dipolar couplings. The new experiment, termed FSR (frequency selective REDOR),
C P, Jaroniec, B A, Tounge, J, Herzfeld, R G, Griffin   +3 more
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15N,15N spin-spin coupling constants across N?H?N and N?H+?N hydrogen bonds: can coupling constants provide reliable estimates of N?N distances in biomolecules?

Magnetic Resonance in Chemistry, 2001
Predictive quantum chemical methods based upon coupled cluster theory of spin–spin coupling constants offer a direct tool to explore a variety of questions concerning the relationship between coupling constants and intermolecular distances, molecular orientation, changes in hybridization and related issues.
Janet E. Del Bene, S. Ajith Perera, Rodney J. Bartlett   +2 more
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On the Aleksandrov problem for mappings preserving fuzzy n -distance in fuzzy n -normed spaces

Journal of Intelligent & Fuzzy Systems, 2019
We study the problem of Aleksandrov in fuzzy n -normed spaces and prove that every surjective fuzzy function preserving unit n -distance is affine, and thus is a fuzzy n -isometry.
Hassan Noori Esfahani, Reza Saadati
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On the Relationship Between Multidistances and n-Distances Revisited

2023
Tomasa Calvo Sánchez, Pilar Fuster-Parra   +1 more
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On the Aggregation of n-distances

2022
Tomasa Calvo Sánchez, Pilar Fuster-Parra   +1 more
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Assessing dissimilarity of random sets using envelope test and test based on N-distances

2016
This contribution concerns comparing of random sets given (digital) images of their realisations. In classical statistics, being able to specify a particular model is of great benefit, since we can for example estimate and compare the model parameters. Unfortunately, it is not necessarily feasible.
Gotovac Đogaš, Vesna, Ugrina, Ivo
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