It has been known that structures having a nitrogen at the 1-position and an oxygen functional group at the 3-position are one of the most important units common in pharmaceuticals, etc. β-aminoketones are important intermediates for providing such important units.
Conjugate addition reactions of nitrogen nucleophiles with α,β-unsaturated compounds, called Aza-Michael reactions, are known as common methods for synthesizing the β-aminoketones to be used as the intermediates.
However, the conventional methods of synthesizing the β-aminoketones by the Aza-Michael reactions are disadvantageous in that these are inefficient reaction processes, selectivity and yield not always being satisfactory. Under such circumstances, Spencer, et al. have recently reported a method of using a carbamate as a nitrogen nucleophile in the presence of a PdCl2(CH3CN)2 complex catalyst (Org. Lett., 2001, 3, 25).
However, also in the method using the PdCl2(CH3CN)2 complex catalyst, there are restrictions in the types of the (α,β-unsaturated ketones and the carbamates and the reaction conditions, and yield and efficiency of the reaction are insufficient for practical use.
Accordingly, an object of the invention is to overcome the conventional problems, thereby providing a novel technology for synthesizing various β-aminoketones by an Aza-Michael reaction with high yield and efficiency.
USPTO Backgrounds
USPTO Backgrounds