Chromium tricarbonyl complexes of methyl O-methylpodocarpate: differentiation of diastereomers by high field NMR spectroscopy

The reaction of Cr(CO)6 with methyl O-methylpodocarpate yields diastereomeric complexes in which the Cr(CO)3 fragment binds to either the α- or the β-face of the aromatic C ring of the diterpenoid. These isomers are separable using reverse phase high pressure liquid chromatography and their 1H and 13C NMR spectra have been recorded at 500 and 125 MHz, respectively. By use of the 1H1H COSY and 1H13C shift-correlated two-dimensional spectra all …