Daisuke Yamamoto, Daisuke Matsukawa, Ryusei Kikuchi, Yuki Narushima, Yuta Kumakura, Mana Ito, Kazuishi Makino
The stereoselective 5- endo -trig oxygenative cyclization of α,β-unsaturated oximes was achieved using molecular oxygen (O2 ) and a manganese catalyst. Several 4-hydroxy-4,5-dihydroisoxazoles were obtained in high yields by directly incorporating O2 from the atmosphere (eliminating the necessity for a pure oxygen environment) and using an unprecedentedly low loading of Mn(acac)3 (as little as 0.020 mol %) without additional additives. Because of its desirable features, such as operational simplicity, inexpensive catalyst, mild reaction conditions (open flask conditions at room temperature), and broad substrate compatibility, this novel reaction provides an attractive synthetic approach to producing 4-hydroxy-4,5-dihydroisoxazoles...
April 18, 2024: Journal of Organic Chemistry