A novel asymmetric synthesis of highly enantiomerically enriched norbornane-type diamine derivatives

Abstract

The simple and highly enantioselective methanolysis of norbornene dicarboxylic acid anhydride mediated by quinidine leads to the corresponding cis-monomethyl ester with 98% ee. By means of selective ester epimerization, followed by Curtius degradation of the intermediate trans-diacyl azide, two optically active norbornane-type diamines are obtained as their hydrochloric salts. Liberating the amine with an excess of triethylamine in situ and subsequent derivatization affords potential C₁-symmetric ligands for asymmetric catalysis in excellent yields.