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排序方式: 共有121条查询结果,搜索用时 218 毫秒
1.
Chiu-Hong Lin Michael D. Ennis Robert L. Hoffman Gillian Phillips Susanne R. Haadsma-Svensson Nabil B. Ghazal Connie G. Chidester 《Journal of heterocyclic chemistry》1994,31(1):129-139
An efficient synthesis of the potent and orally active 5-HT1A agonists, (R)-(+)- and (S)-(-)-1-formyl-6,7,8,9-tetrahydro-N,N-dipropyl-3H-benz[e]indol-8-amines 1a and 1b , is described. This synthesis was accomplished in twelve steps from commercially available 1,5,6,7-tetrahydro-4H-indol-4-one ( 5 ). The key step involved a regio-controlled Friedel-Crafts acylation of 1-(p-toluenesulfonyl)indol-4-acetyl chloride with ethylene to yield a versatile synthon, 3-(p-toluenesulfonyl)-6,7,8,9-tetrahydro-3H-benz[e]indol-8-one ( 10 ). Subsequent coupling of this ketone with chiral α-methylbenzylamine under reductive amination conditions yielded a mixture of diastereomers. These diastereomers were efficiently separated by either chromatography or fractional recrystallization of the derived hydrochloride salts. Debenzylation of the pure diastereomers was followed by alkylation and formylation to yield (R)-(+)- and (S)-(-)-enantiomers 1a and 1b with >99% purity. 相似文献
2.
Baptiste Demoulin Margherita Maiuri Tetyana Berbasova Prof. James H. Geiger Prof. Babak Borhan Prof. Marco Garavelli Prof. Giulio Cerullo Prof. Ivan Rivalta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(66):16389-16400
Artificial biomimetic chromophore-protein complexes inspired by natural visual pigments can feature color tunability across the full visible spectrum. However, control of excited state dynamics of the retinal chromophore, which is of paramount importance for technological applications, is lacking due to its complex and subtle photophysics/photochemistry. Here, ultrafast transient absorption spectroscopy and quantum mechanics/molecular mechanics simulations are combined for the study of highly tunable rhodopsin mimics, as compared to retinal chromophores in solution. Conical intersections and transient fluorescent intermediates are identified with atomistic resolution, providing unambiguous assignment of their ultrafast excited state absorption features. The results point out that the electrostatic environment of the chromophore, modified by protein point mutations, affects its excited state properties allowing control of its photophysics with same power of chemical modifications of the chromophore. The complex nature of such fine control is a fundamental knowledge for the design of bio-mimetic opto-electronic and photonic devices. 相似文献
3.
Host–Guest Assembly of a Molecular Reporter with Chiral Cyanohydrins for Assignment of Absolute Stereochemistry
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Hadi Gholami Dr. Mercy Anyika Jun Zhang Dr. Chrysoula Vasileiou Prof. Dr. Babak Borhan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9235-9239
The absolute stereochemistry of cyanohydrins, derived from ketones and aldehydes, is obtained routinely, in a microscale and derivatization‐free manner, upon their complexation with Zn‐MAPOL, a zincated porphyrin host with a binding pocket comprised of a biphenol core. The host–guest complex leads to observable exciton‐coupled circular dichroism (ECCD), the sign of which is easily correlated to the absolute stereochemistry of the bound cyanohydrin. A working model, based on the ECCD signal of cyanohydrins with known configuration, is proposed. 相似文献
4.
Ghazal Montaseri Mohammad Javad Yazdanpanah 《Communications in Nonlinear Science & Numerical Simulation》2012,17(1):388-404
In this paper, a model predictive control (MPC) scheme for a class of parabolic partial differential equation (PDE) systems with unknown nonlinearities, arising in the context of transport-reaction processes, is proposed. A spatial operator of a parabolic PDE system is characterized by a spectrum that can be partitioned into a finite slow and an infinite fast complement. In this view, first, Galerkin method is used to derive a set of finite dimensional slow ordinary differential equation (ODE) system that captures the dominant dynamics of the initial PDE system. Then, a Multilayer Neural Network (MNN) is employed to parameterize the unknown nonlinearities in the resulting finite dimensional ODE model. Finally, a Galerkin/neural-network-based ODE model is used to predict future states in the MPC algorithm. The proposed controller is applied to stabilize an unstable steady-state of the temperature profile of a catalytic rod subject to input and state constraints. 相似文献
5.
Hosseinikhah Seyed Mahdi Beigzadeh Borhan Siavashi Majid Halabian Mahdi 《Journal of Thermal Analysis and Calorimetry》2020,141(5):1543-1558
Journal of Thermal Analysis and Calorimetry - High interstitial fluid pressure in the tumor is among the most important barriers to drug delivery. The use of the static magnetic field is one of the... 相似文献
6.
The activity of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex, A (MOBPPY = 4‐methoxybenzoylmethylenetriphenyl‐ phosphoraneylide), was investigated in the Heck–Mizoroki C? C cross‐coupling reaction under conventional heating and microwave irradiation conditions. The complex is an active and efficient catalyst for the Heck reaction of aryl halides. The yields were excellent using a catalytic amount of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex in N‐methyl‐2‐pyrrolidinone (NMP) at 130 °C and 600 W. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
7.
Daniel C. Steigerwald Bardia Soltanzadeh Aritra Sarkar Cecilia C. Morgenstern Richard J. Staples Babak Borhan 《Chemical science》2021,12(5):1834
Intermolecular asymmetric haloamination reactions are challenging due to the inherently high halenium affinity (HalA) of the nitrogen atom, which often leads to N-halogenated products as a kinetic trap. To circumvent this issue, acetonitrile, possessing a low HalA, was used as the nucleophile in the catalytic asymmetric Ritter-type chloroamidation of allyl-amides. This method is compatible with Z and E alkenes with both alkyl and aromatic substitution. Mild acidic workup reveals the 1,2-chloroamide products with enantiomeric excess greater than 95% for many examples. We also report the successful use of the sulfonamide chlorenium reagent dichloramine-T in this chlorenium-initiated catalytic asymmetric Ritter-type reaction. Facile modifications lead to chiral imidazoline, guanidine, and orthogonally protected 1,2,3 chiral tri-amines.Intermolecular haloamination reactions are challenging due to the high halenium affinity of the nitrogen atom. This is circumvented by using acetonitrile as an attenuated nucleophile, resulting in an enantioselective halo-Ritter reaction. 相似文献
8.
Xiao Zhou Yali Lu Wenjing Wang Babak Borhan Gavin E. Reid 《Journal of the American Society for Mass Spectrometry》2010,21(8):1339-1351
Protein surface accessible residues play an important role in protein folding, protein-protein interactions and protein-ligand
binding. However, a common problem associated with the use of selective chemical labeling methods for mapping protein solvent
accessible residues is that when a complicated peptide mixture resulting from a large protein or protein complex is analyzed,
the modified peptides may be difficult to identify and characterize amongst the largely unmodified peptide population (i.e.,
the ‘needle in a haystack’ problem). To address this challenge, we describe here the development of a strategy involving the
synthesis and application of a novel ‘fixed charge’ sulfonium ion containing lysine-specific protein modification reagent,
S,S′-dimethylthiobutanoylhydroxysuccinimide ester (DMBNHS), coupled with capillary HPLC-ESI-MS, automated CID-MS/MS, and data-dependant
neutral loss mode MS3 in an ion trap mass spectrometer, to map the surface accessible lysine residues in a small model protein, cellular retinoic
acid binding protein II (CRABP II). After reaction with different reagent:protein ratios and digestion with Glu-C, modified
peptides are selectively identified and the number of modifications within each peptide are determined by CID-MS/MS, via the
exclusive neutral loss(es) of dimethylsulfide, independently of the amino acid composition and precursor ion charge state
(i.e., proton mobility) of the peptide. The observation of these characteristic neutral losses are then used to automatically
‘trigger’ the acquisition of an MS3 spectrum to allow the peptide sequence and the site(s) of modification to be characterized. Using this approach, the experimentally
determined relative solvent accessibilities of the lysine residues were found to show good agreement with the known solution
structure of CRABP II. 相似文献
9.
Estimation of the spectral measure, covariance and spectral density functions of a strictly stationaryr- vector valued time series is considered, under the assumption that some of the observations are missed. The modified periodograms are calculated using data window. The asymptotic normality is studied. 相似文献
10.
Highly Stereoselective Intermolecular Haloetherification and Haloesterification of Allyl Amides
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Bardia Soltanzadeh Dr. Arvind Jaganathan Dr. Richard J. Staples Prof. Dr. Babak Borhan 《Angewandte Chemie (International ed. in English)》2015,54(33):9517-9522
An organocatalytic and highly regio‐, diastereo‐, and enantioselective intermolecular haloetherification and haloesterification reaction of allyl amides is reported. A variety of alkene substituents and substitution patterns are compatible with this chemistry. Notably, electronically unbiased alkene substrates exhibit exquisite regio‐ and diastereoselectivity for the title transformation. We also demonstrate that the same catalytic system can be used in both chlorination and bromination reactions of allyl amides with a variety of nucleophiles with little or no modification. 相似文献