Structures of Furobinordentatin and Furobiclausarin, Two Novel Bicoumarins from Citrus Plants.

Two novel bicoumarins named furobinordentatin (1) and furobiclausarin (3) have been isolated from the roots of Citrus yuko and C. hassaku, respectively. The structures were elucidated by single crystal X-ray analysis and/or spectroscopic studies as 1 and 3. The structural characteristic of these new bicoumarins is the presence of a tetrahydrofuran ring connecting two nordentatin or clausarin units.