title: Unequivocal NMR assignments: O-methoxy-methyl esters derivatives of acid chromanones from Calophyllum brasiliense CAMB. (Guanandi).
abstract: The present work describes the fractionation of the crude hexane extract (EBHEX) from Calophyllum brasiliense (Clusiaceae) stem bark. Derivatization of DCM(2-9) fraction with diazomethane afforded the chromanones inophylloidic acid, isobrasiliensic acid, as well as, a mixture containing isobrasiliensic and brasiliensic acids, in the form of their more stable O-methoxy-methyl esters derivatives 1, 2, and 3, respectively. The isolation of 1 from C. brasiliense is described for the first time herein. The use of two-dimensional NMR methods ((1)H-COSY, HMQC, and HMBC) allowed the precise determination of (13)C and (1)H chemical shifts of compounds 1, 2, and 3.
authors.affiliation: Department of Chemistry, Universidade Federal de Mato Grosso, Cuiaba, MT, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Caneppele
authors.forename: P C
authors.initials: PC
authors.lastname: Vieira
authors.forename: E L
authors.initials: EL
authors.lastname: Dall'Oglio
authors.forename: L E
authors.initials: LE
authors.lastname: da Silva
authors.forename: P T
authors.initials: PT
authors.lastname: Sousa
mesh_terms: D029759:Calophyllum / Q000737:chemistry*; D002867:Chromones / Q000737:chemistry*; D004952:Esters; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D002867:Chromones; D004952:Esters; D010936:Plant Extracts