title: Through-Space 1,4-Palladium Migration and 1,2-Aryl Shift: Direct Access to Dibenzo[a,c]carbazoles through a Triple C-H Functionalization Cascade.
abstract: A palladium-catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2-arylindoles and diaryliodonium salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected "through-space" 1,4-palladium migration to the 2-aryl moiety, by remote C-H bond activation followed by C-H arylation with diaryliodonium salt, and an unprecedented 1,2-aryl shift take place. Finally, an intramolecular cross-dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C-H bond activation one C-C bond cleavage, and the simultaneous construction of three new C-C bonds in a single operation.
authors.affiliation: Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India), Fax: (+91) 33-2473-5197.|Academy of Scientific and Innovative Research-Kolkata, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India).
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Bhunia
authors.affiliation: Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India), Fax: (+91) 33-2473-5197.|Academy of Scientific and Innovative Research-Kolkata, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India).
authors.forename: Arghya
authors.initials: A
authors.lastname: Polley
authors.affiliation: Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India), Fax: (+91) 33-2473-5197.
authors.forename: Ramalingam
authors.initials: R
authors.lastname: Natarajan
authors.affiliation: Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India), Fax: (+91) 33-2473-5197. rjana@iicb.res.in.|Academy of Scientific and Innovative Research-Kolkata, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India). rjana@iicb.res.in.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Jana
keywords: CH activation; annulation; carbazoles; cascade reactions; palladium