TMSOTf-promoted intermolecular cascade reaction of aromatic diazo ketones with olefins : selective synthesis of 3-arylethylideneoxindoles

• Main Authors: Tatina, Madhu Babu, Wang, Xinzhu, Santoso, Mardi, Moussa, Ziad, Judeh, Zaher M. A.
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Chemical engineering; Hydrocarbons; Aromatic Compounds
• Online Access: https://hdl.handle.net/10356/153874
• Institution: Nanyang Technological University

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.