Structure Determination of Monomeric Phloroglucinol Derivatives with a Cinnamoyl Group Isolated from Propolis of the Stingless Bee, Tetragonula carbonaria

Abstract

AbstractTetragocarbones A and B were isolated from the propolis of an Australian stingless bee, Tetragonula carbonaria. These largely planar structures were proposed as a result of NMR analysis as well as comparison of their NMR data with those of related monomeric phloroglucinol derivatives. To elucidate relative and absolute stereochemistry of tetragocarbone A, the synthesis of the proposed structure of tetragocarbone A was performed. As a result, the synthetic compound bearing stereogenic centers 1R*,3R*,6S* was identical with naturally occurring tetragocarbone A. The absolute stereochemistry of tetragocarbone A was established to be 1R,3R,6S by chiral HPLC separation and X‐ray analysis. Comparison of the NMR data of tetragocarbone A with that of tetragocarbone B indicated that tetragocarbone B would be a natural congener of tetragocarbone A.