Structure determination and MSn analysis of two new lissoclinamides isolated from the Indo-Pacific ascidian Lissoclinum patella: NOE restrained molecular dynamics confirms the absolute stereochemistry derived by degradative methods

Two new lissoclinamides, lissoclinamides 9 and 10 were isolated from an Ind onesian collection of the ascidian Lissoclinum patella along with the known patellamide C. The structures of the lissoclinamides were determined by a combination of 2D NMR, selective 1D TOCSY, MS and MSn techniques. The assig nment of absolute stereochemistry was achieved by the hydrolysis of lissocl inamides 9 and 10 followed by chiral TLC. In the case of lissoclinamide 9, NOE restrained molecular dynamics studies were also performed confirming th e proposed stereochemistry. (C) 2000 Elsevier Science Ltd. All rights reser ved.