TMSOTf-Promoted Intermolecular Cascade Reaction of Aromatic Diazo Ketones with Olefins: Selective Synthesis of 3-Arylethylideneoxindoles

• DOI: 10.1021/acs.joc.0c01076
• Publication Date: 2020-06-22T14:10:01Z
• Authors: Madhu Babu Tatina; Wang Xinzhu; Mardi Santoso; Ziad Moussa; Zaher M. A. Judeh
• Keywords: Aromatic Compounds; :Chemical engineering [Engineering]; 01 natural sciences; Hydrocarbons; 0104 chemical sciences

A simple trimethylsilyl trifluoromethanesulfonate (TMSOTf)-promoted intermolecular cascade reaction of aromatic diazo ketones with olefins has been developed. This method directly gave 3-phenylethylideneoxindoles from 3-diazooxindoles and styrenes with exclusive regioselectivity, chemoselectivity, and E-stereoselectivity. The key to the success of the reaction and higher yields is the elegant use of TMSOTf, which gradually released the active triflic acid promoter in situ. The reaction tolerates a wide substrate scope of 3-diazooxindoles and styrenes with electron-donating and electron-withdrawing groups and works well on the gram scale.