Studies on the Agalwood (Jinko). IV.1) Structures of 2-(2-Phenylethyl)chromone Derivatives, Agarotetrol and Isoagarotetrol

Abstract

The structures of two compounds, AH1and AH2, isolated from agalwood “Jinko” were studied. AH1was obtained as needles having a melting point different from that of agarotetrol (powder) isolated and characterized by Yoshii et al. However, the carbon-13 nuclear magnetic resonance (13C-NMR) data and [α]Dvalues of the two compounds were identical, and AH1was concluded to have the same structure, including stereochemistry, as agarotetrol. The half-chair conformation of the hexenyl ring moiety assumed by Yoshii et al. was confirmed by detailed analyses of the proton nuclear magnetic resonance (1H-NMR) and 2D-COSY spectra. AH2was assigned the structure (55,6R,7R,8S)-2-(2-phenylethyl)-5e’,6e,7e,8e’-tetrahydroxy-5,6,7,8-tetrahydrochromone, a stereo-isomer of agarotetrol (75,8R), on the basis of the 1H-NMR, X-ray analysis and circular dichroism (CD) spectral data. It was named isoagarotetrol. The hexenyl ring moiety of isoagarotetrol was found to have a half-chair conformation identical to that of agarotetrol in the crystalline state as well as in solution. © 1986, The Pharmaceutical Society of Japan. All rights reserved.