The heterogeneous enantioselective hydrodehalogenation of α,α-dichlorobenzazepinone-2: A unique case of substrate specificity.

Abstract

The enantioselective hydrodehalogenation of α,α-dichlorobenzazepinone-2 with cinchona modified Pd- and Pt-catalysts was investigated using a random screening approach. The effect of important reaction parameters was determined and optimized. The best optical yields (50% ee) were obtained with a 5% Pd/BaSO 4 catalyst modified with cinchonine in THF with NBu 3 as HCl acceptor. Very high modifier and catalyst concentrations were necessary to get good optical yields and reasonable rates because the modifier decreases the catalyst activity. The absolute configuration of α-chlorobenzazepinone-2 was determined. Attempts to extend this enantioselective dehalogenation reaction to other α,α-dihalogen substituted acid derivatives were unsuccessful.