Conformational and electronic interaction studies of α-substituted carbonyl compounds. XIV. α-(arylsulfonyl)-p-substituted acetophenones[1]

Article abstract of DOI:10.1080/10426509708033706

The V_CO IR analysis of α-(p-phenylsulfonyl)-p-substituted acetophenones X-oC(O)CH₂S(O)₂o-Y 1-8, being X and Y = NO₂, H and OMe substituents, supported by Molecular Mechanics data of the α-methylsulfonylacetophenone (model compound), indicates the existence of the cis/gauche rotational isomerism. The less polar gauche₂ rotamer is the more stable (conc. ? 90%) and the more polar cis rotamer is the less stable one along the series. Compounds 4 (X = Y = H) and 3 (X = H, Y = OMe) present another less stable and rather polar gauche₁ rotamer. The almost constant carbonyl gauche₂ shifts (Δv_g2) together with the quasi-invariability of the cis/gauche ratios, when X varies and Y is fixed, indicates a very nearly constant summing up of π*_CO/σ_C-SO2 and π_CO/σ*_C-SO2 orbital interactions. The progressive stabilization of the gauche₂ rotamer when X is fixed and Y changes from NO₂ to OMe substituents, along with the parallel decrease of the positive sulfonyl asymmetric frequency shifts (Δv_SO2g2) is discussed in terms of the progressive contribution of the O(_SO2) → C_(CO) electrostatic and charge transfer interactions. Additional support for the proposed interactions is given by the large NAE mean value tor the α-methylene carbon chemical shifts together with the upfield shift of the β-ketosulfones mean carbonyl carbon chemical shifts in relation to that of the β-ketosulfoxides.

Full text of DOI:10.1080/10426509708033706

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: http://www.tandfonline.com/loi/gpss20
CONFORMATIONAL AND ELECTRONIC
INTERACTION STUDIES OF α-SUBSTITUTED
CARBONYL COMPOUNDS. XIV. α-(ARYLSULFONYL)-
p-SUBSTITUTED ACETOPHENONES[1]
Paulo R. Olivato , Sandra A. Guerrero & Roberto Rittner
To cite this article: Paulo R. Olivato , Sandra A. Guerrero & Roberto Rittner (1997)
CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED
CARBONYL COMPOUNDS. XIV. α-(ARYLSULFONYL)-p-SUBSTITUTED ACETOPHENONES[1]
, Phosphorus, Sulfur, and Silicon and the Related Elements, 130:1, 155-174, DOI:
10.1080/10426509708033706
To link to this article: http://dx.doi.org/10.1080/10426509708033706
Published online: 24 Sep 2006.
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Date: 12 June 2016, At: 04:55