scholarly journals Z and E rotamers of N -formyl-1-bromo-4-hydroxy-3-methoxymorphinan-6-one and their interconversion as studied by 1 H/13 C NMR spectroscopy and quantum chemical calculations

2012 ◽  
Vol 51 (2) ◽  
pp. 82-88 ◽  
Author(s):  
Agnieszka Sulima ◽  
Kejun Cheng ◽  
Arthur E. Jacobson ◽  
Kenner C. Rice ◽  
Klaus Gawrisch ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
C Nmr

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene with chiral glyoxylates

1990 ◽  
Vol 55 (1) ◽  
pp. 230-244 ◽  
Author(s):  
Otakar Červinka ◽  
Aleš Svatoš ◽  
Petr Trška ◽  
Pavel Pech
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Absolute Configuration ◽  
Quantum Chemical ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Chemical Correlation ◽  
The Absolute ◽  
C Nmr

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene (I) with chiral (-)-menthyl (II) and (-)-8-phenylmenthyl (III) glyoxylates in various solvents without or with catalysts was studied. The reactions gave a mixture of trans-and cis-isomers of (-)-menthyl (IV) and (-)-8-phenylmenthyl (V) 2-trimethylsilyloxy-5,6-dihydro-2H-pyran-6-carboxylates. The regioselectivity of the reaction was explained by quantum-chemical calculations, the enantioselectivity was determined using 13C NMR spectroscopy and the absolute configuration of the addition products was assigned on the basis of chemical correlation with (S)-(-)-dimethyl malate.

Heterocyclization of (Acridin-9-yl)thiosemicarbazides with Dimethyl Acetylenedicarboxylate

2007 ◽  
Vol 72 (3) ◽  
pp. 347-362 ◽  
Author(s):  
Jana Tomaščiková ◽  
Ján Imrich ◽  
Ivan Danihel ◽  
Stanislav Böhm ◽  
Pavol Kristian
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Reaction Mechanisms ◽  
Quantum Chemical ◽  
Dimethyl Acetylenedicarboxylate ◽  
C Nmr

Two types of (acridin-9-yl)thiosemicarbazides with the acridine moiety in the thiourea part (Acr-NHCS, 10a, 10b) and hydrazine part (Acr-NHNHCS, 12a-12c) were prepared to investigate their reactions with dimethyl acetylenedicarboxylate. Five-membered thiazolidinone derivatives 15a, 15b, 19a-19c were formed; some aspects of corresponding reaction mechanisms are discussed. 1D and 2D 1H and 13C NMR spectroscopy and DFT quantum chemical calculations were used to elucidate the structure of the compounds.

Hydrogen-Bonding and the Dissolution Mechanism of Uracil in an Acetate Ionic Liquid: New Insights from NMR Spectroscopy and Quantum Chemical Calculations

2013 ◽  
Vol 117 (15) ◽  
pp. 4109-4120 ◽  
Author(s):  
João M. M. Araújo ◽  
Ana B. Pereiro ◽  
José N. Canongia Lopes ◽  
Luís P. N. Rebelo ◽  
Isabel M. Marrucho
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dissolution Mechanism

Organoboranes and tetraorganoborates studied by 11B and 13C NMR spectroscopy and DFT calculations

2015 ◽  
Vol 70 (6) ◽  
pp. 421-424 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
13C Nmr ◽  
Quantum Chemical ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Line Widths ◽  
Nmr Signals ◽  
C Nmr ◽  
Extract Information

AbstractCare should be taken on recording the sometimes elusive 13C NMR signals for boron-bonded carbon atoms, since it is easy to extract information about coupling constants 1J(13C,11B) by measuring the respective line widths of 13C(B-C) and 11B NMR signals. This information can be confirmed by quantum-chemical calculations [B3LYP (6-311+G(d,p) level of theory] of nJ(13C,11B) in organoboranes and tetraorganoborates. For the latter, the signs for n = 2, 3, 4 were experimentally determined.

scholarly journals Argentate(i) and (iii) complexes as intermediates in silver-mediated cross-coupling reactions

2018 ◽  
Vol 54 (40) ◽  
pp. 5086-5089 ◽  
Author(s):  
Sebastian Weske ◽  
Richard A. Hardin ◽  
Thomas Auth ◽  
Richard A. J. O’Hair ◽  
Konrad Koszinowski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Esi Mass Spectrometry

Silver-mediated cross-coupling reactions proceed via anionic ate complexes, which have been characterized by a combination of NMR spectroscopy, ESI mass spectrometry, and quantum-chemical calculations.

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