PEPTIDE COUPLING REACTIONS OF THE MYCOTOXIN SPORIDESMIN - SYNTHESIS OF SPORIDESMIN HEMISUCCINATES, X-RAY CRYSTAL-STRUCTURE OF SPORIDESMIN-A 11-HEMISUCCINATE, AND ITS COUPLING WITH N-ALPHA-TERT-BOC-L-LYSINE METHYL-ESTER

Coupling reactions of the potent mycotoxin sporidesmin A were studied for the development of immunogenic protein conjugates. Acylation of sporidesmin D and sporidesmin A with benzoic anhydride in the presence of 4-(dimethylamino)pyridine and triethylamine led to the 10b,11-dibenzoates and 10b-benzoates. Succinoylation of sporidesmin A with succinic anhydride under similar conditions led to a mixture of the 10b,11-dihemisuccinate and the 10b- and 11-hemisuccinates. The structure of sporidesmin A 11-hemisuccinate was confirmed by X-ray crystallography. Sporidesmin A 11-hemisuccinate was coupled to N(alpha)-t-Boc-lysine methyl ester in buffered aqueous dimethylformamide using tributylamine and isobutyl chloroformate activation.