エラジタンニンの全部合成を志向した合成法の発展

抄録

This review describes synthetic methods that have brought remarkable increase of synthesizable ellagitannins. Acquisition of capability to enable syntheses of all ellagitannins, which are more than 1,000 characterized natural products and their analogues, would contribute to development of understanding structure-activity relationship. The two major reasons diversifying the structures of ellagitannins are the presence of the hexahydroxydiphenoyl group and the C-O digallates, each of which arises through formation of a C-C or a C-O bond between two galloyl groups. To increase the number of synthesizable ellagitannins, establishment of methods for synthesizing these two components and for assembling the components to construct ellagitannin molecules are essential. Three focuses here are methods for synthesizing (1) the hexahydroxydiphenoyl group, (2) glucose derivatives with hexahydroxydiphenoyl bridges, and (3) the C-O digallates. In addition, several applications of these methods for total syntheses of ellagitannins are exemplified.