¹H NMR study of the substituent transmission effects through SO₂and CO groups in p,p′-disubstituted derivatives of phenyl phenacyl sulphones (β-keto sulphones)

Abstract

The NMR proton chemical shifts of the CH, group in phenyl phenacyl sulphones (p-keto sulphones) p-X-C6H4S0,CH2COC6H4-Y-p, measured in (CD,), are used t o study transmission of the substituent effect through SO, and CO groups. Contrary to the estimation of this effect from CH,acidities [p(SO,) < p ( C 0 ) l 4 the results were that p(S0,) > p(CO), and it was shown that application of a ; gives a significantly better correlation than that with a,. These findings have been interpreted on the basis of structural data.

Predominance of inductive over resonance substituent effect on33S NMR chemical shifts of 4-substituted phenyl-4′-methylphenacyl sulfones

“…1 H NMR chemical shifts for numerousˇ-keto sulfones have been published. 13 Important 13 C NMR data for compounds 1-10 are collected in Table 1. The substituent chemical shifts are 1.07, 0.38, 0.66 and 0.55 ppm for , υ(CO) and υ C-1 0 which are next after sulfur atom to feel the influence of R. It is noteworthy that this effect becomes less visible with increasing distance between the carbon and sulfur atoms:…”

“…Syntheses of 4-substituted phenyl-4 0 -methylphenacyl sulfones have been reported previously. 13 Their NMR spectra were recorded for solutions in CD 3 CN at 30°C for 13 C and 33 S and at 75°C for 17 O. Detailed experimental conditions for recording 13 C NMR spectra were given in our recent paper.…”

“…13 Their NMR spectra were recorded for solutions in CD 3 CN at 30°C for 13 C and 33 S and at 75°C for 17 O. Detailed experimental conditions for recording 13 C NMR spectra were given in our recent paper. 8 13 C NMR chemical shift assignments are based on two-dimensional homonuclear 1 H, 13 C DQF COSY and inverse detected two-dimensional heteronuclear 1 H, 13 C HMQC and 1 H, 13 C HMBC measurements.…”

“…Detailed experimental conditions for recording 13 C NMR spectra were given in our recent paper. 8 13 C NMR chemical shift assignments are based on two-dimensional homonuclear 1 H, 13 C DQF COSY and inverse detected two-dimensional heteronuclear 1 H, 13 C HMQC and 1 H, 13 C HMBC measurements. 17 O and 33 S NMR spectra were recorded with a Bruker Avance DRX 500 spectrometer equipped with a direct 5 mm diameter multinuclear probehead working at 67.82 and 38.39 MHz, respectively.…”

“…4 The chemical shifts of methylene protons in the spectra ofˇ-keto sulfones ArCOCH 2 SO 2 C 6 H 4 R were found to be linearly dependent on and especially on C substituent constants. 4,13 Differing from the substituent effect on the pK a values of compounds of formula p-R 0 C 6 H 4 COCH 2 SO 2 C 6 H 4 R-p, 5 the 1 H NMR spectra show that the substituent effect is more effectively transmitted to the methylene protons from R 0 than from R. 13 X-ray diffraction 14,15 and photoelectron spectral studies 14 and ab initio calculations 14 show that there are some interesting non-bonded interactions inˇ-keto sulfones that may affect transmission of the substituent effect in these compounds. Thus, the oxygen atom of the SO 2 group points toward the oppositely charged carbonyl carbon atom, from which it is separated by a distance shorter than the sum of their van der Waals radii.…”