نتایج جستجو برای: stereoelectronic interactions

تعداد نتایج: 387939  

1999
Frank Alber Gerd Folkers Paolo Carloni

Frank Alber,†,‡,§ Gerd Folkers,‡ and Paolo Carloni*,†,§,| International School for AdVanced Studies SISSA/ISAS, Via Beirut 4 I-34014 Trieste, Italy, Department of Pharmaceutical Chemistry, Swiss Federal Institute of Technology (ETH), CH-8057 Zürich, Switzerland, INFM-Istituto Nazionale per la Fisica della Materia, Italy, International Centre for Genetic Engineering and Biotechnology, AREA Scien...

Journal: :ACS chemical biology 2010
Amit Choudhary Kimberli J Kamer Matthew W Powner John D Sutherland Ronald T Raines

A plausible route for the spontaneous synthesis of an activated ribonucleotide that is poised for polymerization has been put forth (Powner et al. (2009) Nature, 459, 239-242). A key step in this route necessitates the regioselective phosphorylation of the secondary alcohol on C(3') of an anhydroarabinonucleoside in the presence of the primary alcohol on C(5'). Here, we propose that this regios...

Journal: :Bulletin of the Chemical Society of Japan 1989

Journal: :Organic letters 2006
Yan Zhao Donald G Truhlar

It has recently been pointed out that current density functionals are inaccurate for computing stereoelectronic effects and energy differences of isomerization reactions and isodesmic reactions involving alkanes; this has been interpreted as an incorrect prediction of medium-range correlation energies. This letter shows that the recently published M05-2X functional has good accuracy for all thr...

Journal: :Molecules 2011
Chin Hui Kee Azhar Ariffin Khalijah Awang Ibrahim Noorbatcha Koichi Takeya Hiroshi Morita Chuan Gee Lim Noel Francis Thomas

The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl(3) promoted cyclization to produce on...

Journal: :Dalton transactions 2010
Lesley C Lewis-Alleyne Makeba B Murphy-Jolly Xavier F Le Goff Andrew J M Caffyn

We report a one-step synthesis of the phosphine, PPh(2)(i)C(3)F(7) from commercially available precursors. The stereoelectronic properties of the phosphine were probed by coordination to transition metals. Mo(CO)(5)PPh(2)(i)C(3)F(7) was synthesised and the synthesis and structure of trans-PtCl(2)(PPh(2)(i)C(3)F(7))(2) are described. PPh(2)(i)C(3)F(7) was found to be a bulky electron-withdrawing...

Journal: :The Journal of organic chemistry 2011
Amit Choudhary Kimberli J Kamer Ronald T Raines

Stereoelectronic effects modulate molecular structure, reactivity, and conformation. We find that the interaction between the ester and carboxyl moieties of aspirin has a previously unappreciated quantum mechanical character that arises from the delocalization of an electron pair (n) of a donor group into the antibonding orbital (π*) of an acceptor group. This interaction affects the physicoche...

Journal: :Proceedings of the National Academy of Sciences 1995

2011
Guy L. Plourde

This study was aimed at determining the effect, if any, that steric factors may have on the diastereoselectivity in the spiroannulation of simple phenols. A series of phenols bearing different size substituents ortho to the phenolic hydroxyl were synthesized and spiroannulated to the corresponding spiroethers in good to excellent yields (76-94%). However, the diastereoselectivity of the reactio...

Journal: :Chemistry 2013
Nathan B Bennett Douglas C Duquette Jimin Kim Wen-Bo Liu Alexander N Marziale Douglas C Behenna Scott C Virgil Brian M Stoltz

Eeny, meeny, miny ... enaminones! Lactams and imides have been shown to consistently provide enantioselectivities substantially higher than other substrate classes previously investigated in the palladium-catalyzed asymmetric decarboxylative allylic alkylation. Several new substrates have been designed to probe the contributions of electronic, steric, and stereoelectronic factors that distingui...

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