New diarylheptanoids and a hydroxylated ottelione from Ottelia alismoides.

Ten new diarylheptanoids (2, 3, 4, 5a-d, 6, 7, and 8) have been isolated from an extract of 
Ottelia alismoides. The structures of these previously unknown metabolites were determined 
by NMR spectroscopic analysis. A previously unknown, hydroxylated analog of the known 
otteliones A and B (1a and 1b)_namely, 3a-hydroxyottelione (13)_was also isolated. The 1H 
NMR analysis of the Mosher esters of alcohols derived from otteliones A and B (S-17/R-17 
and S-20/R-20) are also reported.