PHOTOCHEMICAL OXIDATION OF VINDOLINE and 16-O-ACETYLVINDOLINE |
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| Authors: | Frank JFilippelli S E Reeg FSima Sariaslani M W Duffel J P N Rosazza |
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| Institution: | Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, USA |
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| Abstract: | Abstract— Photooxidation of 16-O-acetylvindoline in methanol using chlorpromazine-HCl as a photosensitizing agent produces nearly quantitative yields of an iminium derivative. The 16-O-acetylvindol-ine-iminium product was characterized spectrally by proton NMR and mass spectrometry; and by chemical reduction with sodium borodeuteride. Proton NMR and mass spectral analyses of the reduced product revealed that deuterium was stereospecifically incorporated into the 3-a-position. The iminium product formed by photochemical oxidation is identical to that produced by copper oxidases and peroxidase. Photochemical oxidation provides direct evidence for the involvement of free radicals in Aspidosperma alkaloid transformations. |
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