SYNTHESIS OF ETHYL ortho-SUBSTITUTED BENZOYLACETATES AND INVESTIGATION OF THE INFLUENCE OF ortho-SUBSTITUENTS ON KETO-ENOL TAUTOMERISM AND MS FRAGMENTATION BEHAVIOUR
A series of seven ethyl 2-acetyl-(2-substituted benzoyl)acetates II-VIII was synthesized, together with their parent compound I, from the corresponding acid chlorides.The tautomerism of these β-tricarbonyl compounds in tetrachloromethane was studied by 1H NMR spectroscopy and former results concerning this problem were critically evaluated.A further series of seven ortho-substituted ethyl benzoylacetates X-XV and XVII was obtained from the corresponding precursors II-VIII.The keto-enol tautomerism of these β-keto esters was studied by 1H NMR in different solventsand compared with ethyl benzoylacetate IX as standard.Differences caused by the ortho-substituents are discussed.Investigation of the mass spectrometric fragmentation of the β-keto esters IX-XV and XVII showed both common fragmentation pathways due to the same substance class and typical differences in relative intensities according to the nature of the ortho-substituent.
Sicker, Dieter,Mann, Gerhard
p. 839 - 850
(2007/10/02)
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