Madeleine M. Joullié :

Didemnins are a group of marine natural products which exhibit a broad spectrum of biological activities. An X-ray crystal structure analysis of the hydrobromide, (1), which contains the common cyclic core of didemnins was performed on a sample synthesized by the Joullié research group. Analysis of this compound and natural didemnin B revealed some conformational discrepancies which may be responsible for the striking difference in biological activities.

Below are ORTEP representations of the two molecules in the asymmetric unit showing intramolecular hydrogen bonds :


N-t-Butoxycarbonyl-L-3S,4R-dichloroproline methyl ester appears in only five products in the world: astins A, B and C, and the structurally similar cyclochorotine and islanditoxin. The Joullié group has synthesized this amino acid for incorporation into their syntheses of the astins. X-ray crystallography was necessary to establish the cis stereochemistry as shown in the natural products.

To perform real-time measurements on this molecule go here.