Unequivocal NMR assignments: O-methoxy-methyl esters derivatives of acid chromanones from Calophyllum brasiliense CAMB. (Guanandi) |
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Authors: | Caneppele D Vieira P C Dall'Oglio E L da Silva L E Sousa P T |
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Affiliation: | Department of Chemistry, Universidade Federal de Mato Grosso, Cuiaba, MT, Brazil. |
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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. |
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