The first example of a Cu-catalyzed asymmetric O-nitrosocarbonyl aldol reaction is described. This novel protocol allows convenient access to highly enantioenriched alpha-hydroxy-beta-ketoesters including the antibacterial natural. product kjellmanianone (up to 99% ee). MnO2 was introduced. as a:mild efficient oxidant for the in situ generation of nitrosocarbonyl species from hydroxamic acid derivatives.