Carbene-catalyzed indole 3-Methyl C(sp3)-H bond functionalization

• Main Authors: Cheng, Jian, Sun, Jun, Yan, Jiekuan, Yang, Song, Zheng, Pengcheng, Jin, Zhichao, Chi, Robin Yonggui
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Chemistry; N-heterocylic Carbene; Ketones
• Online Access: https://hdl.handle.net/10356/137628
• Institution: Nanyang Technological University

The metal-free catalytic functionalization of aromatic sp2-carbons and benzylic sp3-carbons remains challenging. Here we report a carbene-catalyzed functionalization of the 3-methyl sp3-carbon attached to 2-formyl-indoles. The reaction proceeds through an NHC-bound o-quinodimethane as the key intermediate generated from 2-formyl-3-methylindoles under oxidative conditions. Reactive ketones are found to be effective substrates to produce substituted hydropyrano[3,4-b]indoles in good to excellent yields.