Coumarins from Seseli hartvigii

Abstract

Linear-type furocoumarins, 5-[(2″ E,6″R)-6″-hydroxy-3″,7″-dimethylocta-2″,7″-dienyloxy]psoralen and 5-[(2″ E,6″ S)-6″-hydroxy-3″,7″-dimethylocta-2″,7″-dienyloxy]psoralen (1) were first isolated from whole plants of Seseli hartvigii together with one new natural product 6-(3’-methyl-2’-oxo-3’-butenyl)-7-methoxycoumarin (2), and four known compounds (tamarin, bergaptol, notoptol, and a mixture of β-sitosterol and stigmasterol). The structure of 1 was elucidated by extensive spectroscopic analysis and chemical conversion. The modified Mosher's method and HPLC were applied to determine its stereochemistry. Both R- and S-configurations exist in 1; after modification by Mosher's reagent, they were effectively separated, and their ratio was deduced to be 59% and 41%, respectively.