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Anisotropic and hydrogen bonding effects in phenylglyoxamides and mandelamides: theoretical and NMR conformational evaluation
Author(s) -
Gonçalves Biank T.,
Esteves Pierre M.,
Pinto Angelo C.,
Kaiser Carlos R.,
da Silva Fernanda L.,
Miguez Eduardo,
da Silva Joaquim F. M.
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2192
Subject(s) - chemistry , geminal , intramolecular force , moiety , hydrogen bond , computational chemistry , proton nmr , carbon 13 nmr , density functional theory , alkyl , anisotropy , crystallography , stereochemistry , molecule , organic chemistry , physics , quantum mechanics
Interesting anisotropic effects were observed for phenylglyoxamides and their respective mandelamides. Such effects were observed in experimental 1 H and 13 C NMR (in CDCl 3 , CD 3 OD, and DMSO‐ d 6 solvents) and in some cases with good correlation to theoretical 1 H and 13 C NMR DFT–GIAO (B3LYP/6‐311 + + G**//B3LYP/6‐31G*) calculations. A systematic conformational analysis of these compounds was performed in a two‐step methodology, using PM3 and DFT (B3LYP/6‐31G*) calculations; with good accomplishment and computational time economy. It was observed that intramolecular hydrogen bonding plays a significant role in the conformation of such compounds. Finally, a geminal nonequivalence of an NC H 2 moiety, in one of the alkyl side chain (R1 = R2), was found for the tertiary mandelamides studied. Copyright © 2008 John Wiley & Sons, Ltd.
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