Some Recent Aspects in the Structure Elucidation of Natural Products

Although in the past 20 yr a large number of new synthetic approaches have been developed methods of isolation and structural elucidation have changed more dramatically in the last two decades than have those of synthesis. For the purification of natural products more and more different Chromatographie techniques like paper, thin-layer, column, and gas-liquid chromatography are being used. Characterizations of natural products by eiemental analysis, melting points, optical rotation values, and degradation and derivatization reactions are being increasingly supported by parameters of spectroscopic tools like proton nudear magnetic resonance, carbon nuclear magnetic resonance, phosphorus nuclear magnetic resonance, fluorine nuclear magnetic resonance, infrared spectroscopy, Raman spectroscopy, absorption spectroscopy, optical rotatory dispersion, circular dichroism, magnetic circular dichroism and computer analysis.