Hydroxy groups nuclear magnetic resonance

Two new alkaloids, ervatinine and stapfinine, have been extracted from the leaves of E. coronaria, a species endemic in Pakistan, which is used in the indigenous system of medicine for the treatment of ophthalmia, in the treatment of wounds, and as an anthelmintic. The structures of both alkaloids were deduced from their mass and nuclear magnetic resonance (NMR) spectra. Ervatinine (16) is an ll-hydroxy-5-oxovoaphylline of unknown stereochemistry (47), and stapfinine (17a) appears to have the relative stereochemistry of 5-hydroxyvoaphylline. Again, the configuration of the hydroxyl group is unknown (48). 

Seo S, Tomita Y, Tori K, Yoshimura Y (1978) Determination of the Absolute Configuration of a Secondary Hydroxy Group in a Chiral Secondary Alcohol Using Glycosidation Shifts in Carbon-13 Nuclear Magnetic Resonance Spectroscopy. J Amer Chem Soc 100 3331... 

The nuclear magnetic resonance spectra of SchifF bases formed from primary amines and ortAo-hydroxy aldehydes and ketones show that the Schiff bases derived from l-hydroxy-2-acetonaphthone and from 2-hydroxy-1-naphthaldehyde exist as keto amines (7a) although their formation involves loss of most of the resonance energy of one of the aromatic rings When R is a phenyl group, the phenol-imine tautomer (7b) predominates Schiff bases derived from ortho-hydroxy aldehydes and ketones have the phenol-imine structure (8) . Evidently, in such compounds the keto-amine tautomer... 

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