Conformational Studies by Dynamic NMR. 95.1Rotation around the Adamantyl−Alkyl Bond. Remote Substituent Effect on Conformational Equilibrium

2003 ◽  
Vol 68 (22) ◽  
pp. 8494-8499 ◽  
Author(s):  
J. Edgar Anderson ◽  
Armin de Meijere ◽  
Sergei I. Kozhushkov ◽  
Lodovico Lunazzi ◽  
Andrea Mazzanti
Keyword(s):  
Substituent Effect ◽  
Conformational Equilibrium ◽  
Dynamic Nmr ◽  
Conformational Studies ◽  
Remote Substituent

Conformational studies by dynamic NMR. IX. Activation parameters for the barrier to C-N rotation in N,N-dimethylbenzamidine : a correction

1977 ◽  
Vol 18 (12) ◽  
pp. 1079-1080 ◽  
Author(s):  
Lodovico Lunazzi ◽  
Alessandro Dondoni ◽  
Gaetano Barbaro ◽  
Dante Macciantelli
Keyword(s):  
Activation Parameters ◽  
Dynamic Nmr ◽  
Conformational Studies

ChemInform Abstract: CONFORMATIONAL STUDIES BY DYNAMIC NMR. 7. STEREOCHEMICAL PROCESSES IN 2,3-DIMETHYLBUTANE

1977 ◽  
Vol 8 (41) ◽  
pp. no-no
Author(s):  
L. LUNAZZI ◽  
D. MACCIANTELLI ◽  
F. BERNARDI ◽  
K. U. INGOLD
Keyword(s):  
Dynamic Nmr ◽  
Conformational Studies

Conformational studies by dynamic NMR. Part XV. The rotational barrier of N-methyl aniline

1979 ◽  
Vol 20 (32) ◽  
pp. 3031-3032 ◽  
Author(s):  
Lodovico Lunazzi ◽  
Claudio Magagnoli ◽  
Maurizio Guerra ◽  
Dante Macciantelli
Keyword(s):  
Rotational Barrier ◽  
Dynamic Nmr ◽  
Conformational Studies

Chiral "basket handle" binaphthyl porphyrins: synthesis, catalytic epoxidation and NMR conformational studies

2010 ◽  
Vol 14 (07) ◽  
pp. 646-659 ◽  
Author(s):  
Eric Rose ◽  
Emma Gallo ◽  
Nicolas Raoul ◽  
Léa Bouché ◽  
Ariane Pille ◽  
...  
Keyword(s):  
Time Scale ◽  
Room Temperature ◽  
Conformational Equilibrium ◽  
Variable Temperature ◽  
Conformational Exchange ◽  
Iron Catalysts ◽  
Nmr Studies ◽  
Conformational Studies ◽  
H Nmr ◽  
Catalytic Epoxidation

Three "basket handle" porphyrins have been prepared by condensation of tetrakis-(α,β,α,β-2-aminophenyl)porphyrin atropoisomer with 1,1′-binaphthyl, 2,2′-dimethoxy, -3,3′-dicarbonylchloride, -3,3′-diacetylchloride and -3,3′-dipropanoylchloride. The epoxidation of styrene with the three iron catalysts, obtained after metalation of the free porphyrins, occurs with good yields and moderate ee up to 54%. These porphyrins showed unexpected conformational differences, as revealed by NMR spectroscopy. In particular, variable temperature NMR studies showed that the methoxy group in one of them undergoes intermediate conformational exchange on the 1H NMR time scale at room temperature. Lowering the temperature to -50 °C revealed the presence of four states in slow exchange on the NMR time scale. These results evidence a dynamic conformational equilibrium of the binaphthyl handles that adopt different, asymmetric positions with respect to the porphyrin plane.

scholarly journals Photochemical Transformation of some 3-benzyloxy-2-(benzo[b]thiophen-2-yl)-4Hchromen-4-ones: A Remote Substituent Effect

2018 ◽  
Vol 16 (1) ◽  
pp. 79-86
Author(s):  
Aarti Dalal ◽  
Radhika Khanna ◽  
Ramesh C. Kamboj
Keyword(s):  
Substituent Effect ◽  
Product Yield ◽  
Photochemical Transformation ◽  
Spectroscopic Techniques ◽  
Reaction Site ◽  
State Switching ◽  
Photochemical Transformations ◽  
Remote Substituent ◽  
Electron Donating Groups

AbstractThe effect on photochemical transformations of the substituents present remotely from the reaction site in 3-benzyloxy-2-(benzo[b]thiophen-2-yl)-4H-chromen-4-ones has been determined. The structure(s) of the substrates and photoproducts were established by spectroscopic techniques (UV, IR, and NMR). The substituents had profound effects on product yield and distribution. Electron withdrawing groups (EWGs) on the benzenoid moiety of the chromenone nucleus increased the yield of the photoproducts whereas electron donating groups (EDGs) decreased the yield. These results may be attributed to “state switching” of the substituents during excitation.

Conformational studies of N-carbomethoxy-2-alkoxyindolenines by dynamic NMR, crystallography, and molecular mechanics

Tetrahedron ◽  
2005 ◽  
Vol 61 (37) ◽  
pp. 8809-8820 ◽  
Author(s):  
Oscar R. Suárez-Castillo ◽  
Yaneth M.A. Contreras-Martínez ◽  
Lidia Beiza-Granados ◽  
Myriam Meléndez-Rodríguez ◽  
J. Roberto Villagómez-Ibarra ◽  
...  
Keyword(s):  
Molecular Mechanics ◽  
Dynamic Nmr ◽  
Conformational Studies ◽  
Nmr Crystallography
Sign in / Sign up

Export Citation Format

Share Document