Spectroscopic and theoretical studies of some N-methoxy-N-methyl-2-[(4 '-substituted) phenylsulfonyl]propanamides

Spectroscopic and theoretical studies of some N-methoxy-N-methyl-2-[(4 '-substituted) phenylsulfonyl]propanamides

Author Olivato, Paulo R. Google Scholar
Domingues, Nelson L. C. Google Scholar
Reis, Adriana K. C. A. Autor UNIFESP Google Scholar
Vinhato, Elisangela Google Scholar
Mondino, Mirta G. Google Scholar
Zukerman-Schpector, Julio Google Scholar
Rittner, Roberto Google Scholar
Dal Colle, Maurizio Google Scholar
Institution Universidade de São Paulo (USP)
Fundacao Univ Fed Grande Dourados
Universidade Federal de São Paulo (UNIFESP)
Universidade Federal de São Carlos (UFSCar)
Universidade Estadual de Campinas (UNICAMP)
Univ Ferrara
Fac Osvaldo Cruz
Abstract The analysis of the IR carbonyl band of the N-methoxy-N-methyl-2-[(4'-substituted)phenyisulfonyI]propanamides Y-PhSO(2)CH(Me)C(O)N(OMe)Me (Y = OMe 1, Me 2, H 3, Cl 4, NO(2) 5), supported by HF/6-31G(d,p) calculations of 3,, indicated the existence of two gauche conformers (g(1) and g(2)), the g, conformer being the most stable and the least polar one (in gas phase and in solution). Both conformers are present in solution of the non polar solvent (CCl(4)) for 1-5 and in solution of the more polar solvents (CHCl(3)) for 1. 4, 5 and (CH(2)Cl(2)) for 5, while only the g(1) conformer is present in solution of the most polar solvent (CH(3)CN) for 1-5. the g, and g2 conformers correspond to the enantiomeric pairs of diastereomers (diast(1) and diast(2)) whose relative configurations are [C(3)(R)N(R)]/[C(3)(s)N(s)] and [C(3)(R)N(s)]/[C(3)(s)N(R)], respectively. the computed carbonyl frequencies for g(1) (diast(1)) and g(2) (diast(2)) stereoisomers of3 match well the experimental values. the NBO analysis, for 3 shows the important role of the orbital interactions in conformer stabilization and the overall balance of these interactions corroborates that the g, conformer is more stable than the 92 one. the observed abnormal solvent effect on the relative intensities of the carbonyl doublet components is attributed to the molecular crowding in the g2 conformer which hinders its solvation in comparison to the g, conformer (diast(1)). X-ray single crystal analysis performed for 3 shows the existence of two 92, and g(1b) conformers of diastereomers (diast2, and diast(1b)) whose absolute configurations are [C(3)(R)N(s)] and [C(3)(R)N(R)], respectively. the larger population and. thus, the larger stabilization of the g(2), conformer over the gib form in the crystals may be associated with a larger energy gain deriving from dipole moment coupling in the former conformer along with a series of C-H center dot center dot center dot O electrostatic and hydrogen bond interactions, (C) 2009 Elsevier B.V. All rights reserved.
Keywords Conformational analysis
Infrared spectroscopy
Theoretical calculations
N-methoxy-N-methyl-2-[(4 '-substituted) phenylsulfonyl]propanamides
Language English
Date 2009-10-29
Published in Journal of Molecular Structure. Amsterdam: Elsevier B.V., v. 935, n. 1-3, p. 60-68, 2009.
ISSN 0022-2860 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 60-68
Origin http://dx.doi.org/10.1016/j.molstruc.2009.06.038
Access rights Closed access
Type Article
Web of Science ID WOS:000270603000010
URI http://repositorio.unifesp.br/handle/11600/31892

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