Substituent Influences on the Keto-Enol Tautomerism in 1-(2-Hydroxyphenyl)-3- α - and - β -naphthylpropane-1,3-diones Monitored by
1H and
13C NMR Spectroscopy
Jorge L. Jios
aand Helmut Duddeck
ba Permanent address: LADECOR, Departamento de Quı´mica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, 1900 La Plata, Argentina
b Universität Hannover, Institut für Organische Chemie. Schneiderberg 1B, D-30167 Hannover, Germany
Reprint requests to Dr. Jorge L. Jios. E-mail: jljios@dalton.quimica.unlp.edu.ar Z. Naturforsch.55b, 193Ð202 (2000); received September 27, 1999
1-(2-Hydroxyphenyl)-3α- andβ-naphthylpropan-1,3-diones, Keto-Enol Tautomerism, Substituent Influence,1H NMR Data,13C NMR Data
Synthesis of 18 1-(2-hydroxyphenyl)-3-α- and -β-naphthylpropan-1,3-diones is described.
Their1H and13C NMR spectra were completely and unambiguously assigned using a combi- nation of both homo- and heteronuclear (gs-COSY),1H-detected heteronuclear one-bond (gs-HMQC) and long-range (gs-HMBC) correlation experiments. Substituent and conforma- tion effects on the tautomeric equilibria were identified and interpreted in terms of steric and electronic contributions.
