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Shift reagent 1 H NMR study of methoxycoumarins
Author(s) -
JosephNathan P.,
DomÍnguez M.,
Ortega D. A.
Publication year - 1984
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570210442
Subject(s) - chemistry , reagent , coumarin , lanthanide , ring (chemistry) , flavones , proton nmr , lactone , medicinal chemistry , organic chemistry , ion , chromatography
The complete assignment of the proton chemical shifts of coumarin ( 1 ), all monomethoxy derivatives and the six possible dimethoxyl substituted compounds at the aromatic ring was achieved at 60 MHz in a quantitative study utilizing Pr(fod) 3 as the shift reagent. It was found that in addition to the complexation at the lactone carbonyl a second interaction of the lanthanide shift reagent occurs when two methoxyl groups are found in an ortho distribution. The results are discussed in comparison to data published for flavones in the presence of Pr(fod) 3 shift reagent.