58811-96-4Relevant articles and documents
Formation of a reactive iminium derivative by enzymatic and chemical oxidations of 16-O-acetylvindoline.
Sariaslani,Eckenrode,Beale Jr.,Rosazza
, p. 749 - 754 (1984)
16-O- Acetylvindoline (1a) was oxidatively transformed into an iminium derivative (2a) by copper oxidases (laccase and human ceruloplasmin), an unknown enzyme system(s) of Streptomyces griseus, and the chemical oxidizing agent 2,3-dichloro-5,6- dicyano -1,4-benzoquinone ( DDQ ). The iminium derivative (2a) was isolated from enzymatic and chemical oxidation mixtures and was identified by spectral and chemical techniques. Reduction of the iminium compound with sodium borodeuteride provided monodeuterated 16-O- acetylvindoline (1b) as the sole product. Mass spectral analysis indicated that the deuterium atom was introduced into position C-3 of the piperidine portion of the alkaloid structure. The location and stereochemistry of the deuterium atom were confirmed by high-field 1H and 2H NMR analyses of the deuterated product to be in the 2H alpha orientation. Hydrolysis of the 16-O-acetyl functional group from the iminium derivative (2a) resulted in the production of a previously identified dimer (5), which forms by intramolecular etherification through the reactive enamine (3). The iminium derivative (2a) reacts with cyanide to provide complex mixtures of products, one of which was identified by mass spectrometry as a cyanide addition product. The results confirm the existence of a reactive iminium intermediate formed by all of the biochemical and chemical systems examined.
Photosensitized oxidation, by single-electron transfer, of catharanthine and vindoline: A highly regio- And diastereoselective photocyanation reaction
Cocquet, Guillaume,Rool, Patrice,Ferroud, Clotilde
, p. 2277 - 2281 (2007/10/03)
The irradiation, by visible light, of (+)-catharanthine 1 and of (-)-16-O-acetylvindoline 5 in the presence of cyanide ion and a catalytic amount of a photosensitizer known to produce singlet oxygen leads to (+)-3β-cyanocatharanthine 3 and the new (-)-16-O-acetyl-3α-cyanovindoline 6. The complete stereostructural identification of these compounds has been ascertained by an accurate spectroscopic survey. High regio- and diastereoselectivities (de > 99%) are observed. Some experiments have been performed which confirm unambiguously that singlet oxygen is the oxidizing species in such photochemical conditions. The Royal Society of Chemistry 2000.
