title: An efficient semi-synthesis and structure revision of a cytotoxic triterpenoid 25-acetoxy-3alpha-hydroxyolean-12-en-28-oic acid from Liquidamber styraciflua.
abstract: An efficient partial synthesis of 25-acetoxy-3alpha-hydroxyolean-12-en-28-oic acid (1), starting from oleanolic acid (2), has been developed in an efficient manner (13 steps, 21% yield), employing a photochemical reaction of nitrite 8 for the introduction of C-25 substituting group as the key step. Based on the comparison of its spectral data with those reported for compound 1 isolated from Liquidamber styraciflua, we found the structure in that paper was incorrectly assigned, and should be revised as 3alpha-acetoxy-25-hydroxyolean-12-en-28-oic acid (15).
authors.affiliation: Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Sun
authors.forename: Wei-Shuo
authors.initials: WS
authors.lastname: Fang
authors.forename: Chun
authors.initials: C
authors.lastname: Hu
mesh_terms: D031317:Liquidambar / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009589:Nitrogen Oxides / Q000737:chemistry; D009828:Oleanolic Acid / Q000138:chemical synthesis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D009589:Nitrogen Oxides; D009828:Oleanolic Acid; C087991:nitrosyl chloride