The configuration and conformation of silyl ketene thioacetals derived from 2-pyridyl thioesters were studied by combined NMR and computational analysis. The results revealed that the (E)-silyl ketene thioacetal is always the thermodynamically favoured diastereoisomer; the equilibrium ratio is reversed /E/Z>2:98/ for steric reasons when two O-silyl substituents are present on the C=C double bond, The preferred conformational minima for the E and Z isomers are proposed on the basis of Monte Carlo conformational searches performed on selected model compounds; the computational results are in excellent agreement with the NMR data.
Configurational and conformational analysis of silyl ketene thioacetals by NMR spectroscopy and computational studies / R. Annunziata, V. Molteni, L. Raimondi. - In: MAGNETIC RESONANCE IN CHEMISTRY. - ISSN 0749-1581. - 34:11(1996), pp. 858-864. [10.1002/(SICI)1097-458X(199611)34:11<858::AID-OMR973>3.3.CO;2-T]
Configurational and conformational analysis of silyl ketene thioacetals by NMR spectroscopy and computational studies
R. AnnunziataPrimo
;L. RaimondiUltimo
1996
Abstract
The configuration and conformation of silyl ketene thioacetals derived from 2-pyridyl thioesters were studied by combined NMR and computational analysis. The results revealed that the (E)-silyl ketene thioacetal is always the thermodynamically favoured diastereoisomer; the equilibrium ratio is reversed /E/Z>2:98/ for steric reasons when two O-silyl substituents are present on the C=C double bond, The preferred conformational minima for the E and Z isomers are proposed on the basis of Monte Carlo conformational searches performed on selected model compounds; the computational results are in excellent agreement with the NMR data.Pubblicazioni consigliate
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