title: Synthesis of methyl dihydrohardwickiate and its C-4 epimer. Structural amendment of natural crolechinic acid.
abstract: Reduction of the alpha, beta-unsaturated ester moiety of (+)-methyl hardwickiate with magnesium in methanol afforded methyl (4aS,6S,8aS,1R,5R)-5, 6,8a-trimethyl-5-[2'-(3"-oxoyl)-ethyl-perhydro-1-naphthalenyl]- carboxaylate, while reduction with sodium in n-propanol, followed by esterification with diazomethane, furnished its C-4 epimer. After comparison of the 1H- and 13C-NMR data of these compounds with those reported for crolechinic acid isolated from Croton lechleri, a stereochemical revision for the natural product is suggested.
authors.affiliation: Departamento de Química, UFMS, Mato Grosso do Sul, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Costa
authors.forename: E C
authors.initials: EC
authors.lastname: Perles
authors.forename: F Y
authors.initials: FY
authors.lastname: Fujiwara
authors.forename: P M
authors.initials: PM
authors.lastname: Imamura
mesh_terms: D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism
chemical_list: D004224:Diterpenes; C412190:crolechinic acid; C412189:methyldihydrohardwickiate; D008274:Magnesium