title: The first enantioselective synthesis of the amavadin ligand and its complexation to vanadium.
abstract: The ligand of the naturally occurring vanadium compound amavadin found in Amanita muscaria, (2S, 2'S)-N-hydroxyimino-2,2'-dipropionic acid (1), was synthesized stereoselectively in two steps with 43% overall yield. After complexation of this ligand to vanadyl acetate, amavadin was isolated in quantitative yield. Due to the chirality at vanadium amavadin consists of a mixture of delta and lambda diastereoisomers. Directly after its synthesis, the delta to lambda ratio of amavadin is 2.27 and it decreases to 0.80 after equilibrium has been reached. During this epimerization the optical rotation for V[(2S,2'S)-N-hydroxyimino-(2,2')-dipropionate]2 (=amavadin) changes from [alpha](D)25 = +36 degrees to +114.0 degrees (c = 0.5, H2O). For V[(2R,2'R)-N-hydroxyimino-(2,2')-dipropionate] the optical rotation changes from [alpha](D)25 = -36 degrees to -113.2 degrees (c = 0.5, H2O).
authors.affiliation: Biocatalysis and Organic Chemistry, Delft University of Technology, Julianalaan 136, 2628 BL, Delft, The Netherlands.
authors.forename: Ton
authors.initials: T
authors.lastname: Hubregtse
authors.forename: Ernst
authors.initials: E
authors.lastname: Neeleman
authors.forename: Thomas
authors.initials: T
authors.lastname: Maschmeyer
authors.forename: Roger A
authors.initials: RA
authors.lastname: Sheldon
authors.forename: Ulf
authors.initials: U
authors.lastname: Hanefeld
authors.forename: Isabel W C E
authors.initials: IW
authors.lastname: Arends
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D006877:Hydroxamic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D013237:Stereoisomerism; D014639:Vanadium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006877:Hydroxamic Acids; D008024:Ligands; C502921:N-hydroxyimino-2,2'-dipropionic acid; D014639:Vanadium; D000409:Alanine