The configuration of badrakemin and gummosin, and the identity of isobadrakemin, colladonin, and farnesiferol A
The correlations between farnesiferol A, badrakemin, gummosin, and isobadrakemin have been investigated on the basis of their NMR spectra, which have enabled the configurations at C3, C5, and C9 of the terpenoid coumarins of the iresane group to be determined from their chemical shifts and spin-spin coupling constants.
According to the chemical shifts and spin-spin coupling constants of the signals of the protons at C3, C9, and C10, the configurations of gummosin and badrakemin do not correspond to those proposed previously. It has been established that in badrakemin the substituents at C3 and C9 have the axial orientation and in gummosin they are in the axial and equatorial orientations, respectively.
According to their spectra, physicochemical constants, and mixed melting points, colladonin and isobadrakemin are identical with farnesiferol A.
KeywordsCoumarin Axial Orientation Methine Proton Trans Position Asymmetric Center
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