| Structure Identification: |
| Chem. Pharm. Bull.,1987,35(9):3615-9. | | Homoisoflavonoids and Related Compounds. V.1) A Novel Dibenzoxocin Derivative from Caesalpinia sappan L[Reference: WebLink] | We have been further studying the isolation, absolute stereochemistries and biosyntheses of the phenolic constituents of C. sappan and C. japonica.
METHODS AND RESULTS:
In the present paper,we report the isolation and structural elucidation of a novel dibenzoxocin derivative,10-O-Methylprotosappanin B(1), from Sappan Lignum.10-O-Methylprotosappanin B (1) was obtained by repeated silica gel and Sephadex LH-20 column chromatography, and preparative thin-layer chromatography (PTLC) of the remaining fractions after separation of the previously reported compounds.4) The isolation of the intact compound was so difficult that only a limited amount could be obtained. However, a satisfactory amount was obtained in the form of an isopropylidene derivative (6) from the methanolic extract separated after treatment with acetone in the presence of an acid catalyst, as described in the previous paper.4c) The remaining fractions after isolation of the isopropylidene derivatives of 3,4-dihydroxy homoisoflavans4c) were subjected to column chromatography on silica gel and Sephadex LH-20 to yield 6, together with the isopropylidene derivative of protosappanin B (7). On acid hydrolysis with 60% AcOH, compound 6 was readily transformed into 1. |
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