title: KO(t)Bu-mediated synthesis of dimethylisoindolin-1-ones and dimethyl-5-phenylisoindolin-1-ones: selective C-C coupling of an unreactive tertiary sp3 C-H bond.
abstract: A new reaction for the synthesis of dimethylisoindolinones has been presented from 2-halo-N-isopropyl-N-alkylbenzamide substrates and KO(t)Bu by the selective C-C coupling of an unreactive tertiary sp(3) C-H bond. The reaction manifested an excellent selectivity toward a tertiary sp(3) C-H bond over primary or sec C-H bond. Moreover, biaryl C-C coupling along with alkyl-aryl C-C coupling can be achieved in one pot using dihalobenzamides for the synthesis of biaryl 5-phenylisoindolin-1-ones. It seems that the reaction proceeds via a radical pathway in which the aryl radical translocates via 1,5-hydrogen atom transfer (HAT), forming a tertiary alkyl carbon-centered radical. The generated tertiary alkyl radical could attack the benzamide ring in a 5-exo/endo-trig manner followed by the release of an electron and a proton, leading to a five-membered isoindolinone ring. HAT seems to be responsible for the selective functionalization of the tertiary alkyl group over primary and secondary C-H bonds.
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal , Indore By-pass Road, Bhauri, Bhopal, Madhya Pradesh, India 462 066.
authors.forename: Bhagat Singh
authors.initials: BS
authors.lastname: Bhakuni
authors.forename: Abhimanyu
authors.initials: A
authors.lastname: Yadav
authors.forename: Shailesh
authors.initials: S
authors.lastname: Kumar
authors.forename: Saket
authors.initials: S
authors.lastname: Patel
authors.forename: Shubham
authors.initials: S
authors.lastname: Sharma
authors.forename: Sangit
authors.initials: S
authors.lastname: Kumar