Catalytic transformation of esters of 1,2-azido alcohols into α-amido ketones

Abstract

The esters of 1,2-azido alcohols were transformed into α-amido ketones without external oxidants through the Ru-catalyzed formation of N-H imines with the liberation of N2 followed by intramolecular migration of the acyl moiety. A wide range of α-amido ketones were obtained, and one-pot transformation into the corresponding oxazoles (or a thiazole) was demonstrated.

Ruthenium Bisammine Complex and Its Reaction with Aryl Azides

“…They observed that the Cp^ ligand endows interesting catalytic activities to the ruthenium complex. , Arenes are produced from the reaction of alkynes (Scheme a), while hydrobenzamides are formed in the reaction of benzyl azide (Scheme b) . The catalytic activity of 1 for the transformation of benzyl azide attracted our attention, because N–H benzaldimine was proposed as the key intermediate. , In fact, we found that its catalytic activity is not only limited to the reaction with benzyl azides but also effective for that with alkyl azides to generate the corresponding N–H imines . Various N -acetyl enamides can be synthesized by the catalytic transformation of alkyl azides in the presence of acetic anhydride (Scheme c)…”

Recent advances in the synthesis of α-amino ketones

“…55 In 2016, Park and Rhee demonstrated that the α-hydroxy imine intermediate present in a Heyns rearrangement could be also formed from 1,2-azidoacetates by ruthenium catalysis. 56 The authors reported an improved yield for 1,2-azidoacetates, and this approach was subsequently applied to the synthesis of a wide range of α-amido ketones, forming the products in 53-94% yield.…”

Palladium-Catalyzed C–N Bond Cleavage of 2H-Azirines for the Synthesis of Functionalized α-Amido Ketones

“…The α-amido ketones are very important structural motifs that are widely found in pharmaceuticals and several natural active molecules, such as herbicides, fungicides, and enzyme inhibitors. − They are also important synthetic intermediates, for instance in the synthesis of N -heterocycles such as oxazoles, imidazoles, thiazoles, and others. Therefore, considerable efforts have been devoted to their synthesis. − Nevertheless, some of these synthetic methods suffer from the following drawbacks: the difficulties of preparing starting substrates, rigorous conditions, and/or limitations of the substrate scope. Therefore, new synthetic methods featuring high atomic efficiency and operational simplicity are still under great demand.…”