Apiaceae, Pimpinella anisum, Essential oil, 13 C NMR From the essential oil of Pimpinella anisum fruits a hitherto unknown type of phenylpropane was isolated. The mass, infrared, and 13 C NMR spectra indicate, that the unknown is a 2-methyl-butyric acid ester of 2-hydroxy-5-methoxy-
Undecoupled 13C n.m.r. spectra of a series of asymmetrically trisubstituted benzenes have been obtained by proton ' gated '-decoupling, and show invariablya characteristic sharp doublet in the aromatic region. The origin of this phenomenon is discussed in terms of the indirect 13C-lH coupling pathways available within the ring as dictated by the positions of the substituents. It is shown that a doublet without fine structure arises from the carbon atom having no protons meta, that it is a generally predictable facet of these systems and as such avaluable aid to assignment.
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