Tertiary amine-directed and involved carbonylative cyclizations through Pd/Cu-cocatalyzed multiple C–X (X = H or N) bond cleavage. Issue 40 (27th August 2019)

• Record Type: Journal Article
• Authors: Mu, Qiu-Chao; Nie, Yi-Xue; Bai, Xing-Feng; Chen, Jing; Yang, Lei; Xu, Zheng; Li, Li; Xia, Chun-Gu; Xu, Li-Wen
• Is Part Of: Chemical science. Volume 10:Issue 40(2019)
• Page Start: 9292
• Page End: 9301
• Publication Date: 2019-08-27
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9sc03081f
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : An unprecedented and multiple C–H activation/ N -dealkylative C–N bond activation provides a direct and facile access to indolo[1, 2- a ]quinoxalin-6-ones and phthalides. Abstract : A novel Pd/Cu-cocatalyzed carbonylative cyclization by C–H activation and N -dealkylative C–N bond activation has been developed for the chemoselective construction of synthetically useful heterocycles. The N, N -dimethylamine group on o -indolyl- N, N -dimethylarylamines was found to act as both the directing group and reactive component in this C–H carbonylative cyclization reaction. Furthermore, a unique C–H oxidation/carbonylative lactonization of diarylmethylamines is firstly demonstrated under modified reaction conditions, which could be easily applicable to the one-step synthesis of multi-substituted phthalides bearing an N, O -ketal skeleton that is difficult to access by previously reported methods. Mechanistic studies implicate that Pd/Cu-cocatalyzed C–H oxidation/carbonylative lactonization is a sequential reaction system via Cu-catalyzed C(sp 3 )–H oxidation and Pd-catalyzed oxidative carbonylation of the C(sp 2 )–H bond. It was found that trace amounts of water are essential to promote the Cu-catalyzed C(sp 3 )–H oxidation of diarylmethylamine for the formation of the hydroxyl group, which could act as an in situ -formed directing group in the intramolecular carbonylative lactonization step.