A study of the structure and stereochemistry of ungernia alkaloids by NMR spectroscopy
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1. In a study of the NMR spectra of ungerine, dihydroungerine, hippeastrine, hippeastrine acetate, dihydrohippeastrine, dihydrohippeastrine acetate, and unsevine it has been shown that the B and C rings in these compounds have a cis linkage.
2. It has been found that, in contrast to the alkaloid clivonine, in dihydrohippeastrine the B/C ring-linkage is cis, and the N-CH3 group is located above the plane of the benzene ring.
3. The orientations of the H5, H5a, and H11b protons and the substituent OR at C5 of ring C have been established.
KeywordsLactone Carbonyl Methylenedioxy Group Stereochemical Feature Double Resonance Method Hippeastrine
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