Lysilactones A-C, three 6H-dibenzo[b,d]pyran-6-one glycosides from Lysimachia clethroides, total synthesis of Lysilactone A

Three 6H-dibenzo[b,d]pyran-6-one glycosides named lysilactones A-C (1-3) were isolated from the aerial parts of Lysimachia clethroides. Their structures were elucidated using spectroscopic analysis and chemical evidence. This is the first report of 6H-dibenzo[b,d]pyran-6-one glycosides. Furthermore, we have finished a total synthesis of lysilactone A. The key step is a Suzuki coupling used for the construction of the central biaryl bond. Lysilactone A was prepared in eight steps starting from phloroglucinic acid and orcinol, where the longest linear sequence is seven steps.