Ruthenium-Catalyzed Intramolecular Arene C(sp2)-H Amidation for Synthesis of 3,4-Dihydroquinolin-2(1H)-ones
Wenlong Sun, Cho-Hon Ling, Chi-Ming Au and Wing-Yiu Yu*
*Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong,
Email: wing-yiu.yu
polyu.edu.hk
W. Sun, C.-H. Ling, C.-M. Au, W.-Y. Yu, Org. Lett., 2021, 23, 3310-3314.
DOI: 10.1021/acs.orglett.1c00781
see article for more reactions
Abstract
[Ru(p-cymene)(L-proline)Cl] catalyzes a cyclization of 1,4,2-dioxazol-5-ones to form dihydroquinoline-2-ones in excellent yields with excellent regioselectivity via a formal intramolecular arene C(sp2)-H amidation. The reactions of the 2- and 4-substituted aryl dioxazolones proceed initially through spirolactamization via electrophilic amidation at the arene site.
see article for more examples
proposed mechanism
Procedure for the Ru(II)-Catalyzed Intramolecular C(sp2)-H Bond Amidations
In a glove box, [Ru(p-cymene)(L-proline)Cl] (10 mol %, 3.8 mg) and AgSbF6 (10 mol %, 3.4 mg) were added into a brown 8 mL vial A, the dry TFE (0.5 mL) was added into the vial. The mixture was stirred at room temperature for 5 min. The dioxazolone (0.1 mmol) was added into another 4 mL vial B and dissolved in dry TFE (0.5 mL). The dioxazolone solution was transferred from vial B to vial A. The reaction vial A was sealed and stirred at 50 °C in an oil bath for 12 h. After 12 h, the reaction mixture was passed through Celite eluted with EtOAc (15 mL). The solvent was removed by vacuum and the crude products were purified by preparative thin layer chromatography.
Key Words
ID: J54-Y2021
