Efficient Catalytic Enantioselective Hydroxyamination of α-Aryl-α-Cyanoacetates with 2-Nitrosopyridines

The highly enantioselective totally N-selective hydroxyamination reaction of α-aryl-α-cyanoacetates with 2-nitrosopyridines was realized by using a chiral N,N'-dioxide/Mg(OTf)₂ complex as catalyst, which enriches the nitroso chemistry. A variety of 2-cyano-2-[hydroxyl(pyrydin-2-yl)amino]acetates with quaternary stereocenters and potential antibacterial activities were obtained in excellent yields with good to excellent ee values under as low as 0.05 mol % catalyst loading. The products could be easily transformed to useful α-amino amides and 1,2-diamines. Besides, a possible transition state model was proposed to elucidate the origin of the chirality induction.

Development of N-Substituted Hydroxamic Acids with Pyrazolone Leaving Groups as Nitrosocarbonyl Precursors

A novel class of nitrosocarbonyl precursors, N-substituted hydroxamic acids with pyrazolone leaving groups (NHPY), has been synthesized. Under physiological conditions, these compounds generate nitrosocarbonyl intermediates, which upon hydrolysis release nitroxyl (azanone, HNO) in excellent yields. The amount and rate of nitrosocarbonyl generation are dependent on the nature of the pyrazolone leaving groups and significantly on the structural properties of the NHPY donors. Pyrazolones have been found to be efficient nitrosocarbonyl traps, undergoing an N-selective nitrosocarbonyl aldol reaction. This trapping reaction has been used to confirm the involvement of nitrosocarbonyl intermediates in NHPY aqueous decomposition. In addition, NHPY compounds are shown to generate nitrosocarbonyls efficiently under mild basic conditions in organic solvent and may therefore also enjoy synthetic utility.