The complete assignment of 1H- and 13C-NMR of prenylated xanthones from Tovomita spp. (Guttiferae).

Abstract

A 1,6-dihidroxy-5-(3-metilbut-2-enil)-6’,6’-dimetil-pirano(2’,3’;7,8)- 6”,6”- dimetilpirano (2”,3”;3,2)xantona e a 1,3,6-trihidroxi-6’,6’-dimetil-pirano(2’,3’;7,8)-2,5- di-(3-metilbut-2-enil)xantona tiveram seus deslocamentos químicos de hidrogênio e carbono-13 atribuídos de forma inequívoca, com base nas informações obtidas através dos espectros de RMN de 1H[1D e 2D(1H-1H-COSY) e de correlação heteronuclear 1H-13C-COSY[nJCH(n = 1, 2 e 3)]. Estes da dos ainda foram confirmados utilizando-se a técnica de NOE diferencial. The 1H-and 13C-NMR spec tral data of 1,6-dihydroxy-5-(3-methylbut-2- enyl)-6’,6’-dimethyl-pyrano(2’,3’;7,8)-6”,6”-dimethyl-pyrano(2”,3”;3,2)xanthone and 1,3,6-trihydroxy-6’,6’-dimethyl-pirano(2’,3’;7,8)-2,5-di-(3-methylbut-2-enyl)xanthone have been un am big u ously as signed by the anal y sis of homonuclear (1H-1H-COSY) and heteronuclear [1H-13C-COSY: mod ulated with 1JCH and nJCH (n = 2 and 3, COLOC)] shift-correlated and NOE dif ference spectra.