Catalytic Enantioselective Synthesis of 3,4,5-Trisubstituted Isoxazoline N-Oxides and Regioselective Synthesis of 3,4,5- Trisubstituted Isoxazoles

摘要

An efficient catalytic asymmetric synthesis of 3,4,5- trisubstituted isoxazoline N-oxides and regioselective synthesis of 3,4,5-trisubstituted isoxazoles has been described. α-Nitrocinnamates and α-nitrobenzophenones were utilized as Michael acceptors respectively. Hydroquinine derived thiourea in combination with cesium carbonate was effective for the synthesis of isoxazoline N-oxides whereas stoichiometric di-isopropylethylamine (DIPEA) was the best choice for isoxazole synthesis. In both cases a range of aryl and heteroaromatic groups was tolerated.