title: N-Heterocyclic-Carbene-Catalyzed Umpolung of Imines.
abstract: N-Heterocyclic carbene (NHC) catalysis has been widely used for the umpolung of aldehydes, and recently for the umpolung of Michael acceptors. Described herein is the umpolung of aldimines catalyzed by NHCs, and the reaction likely proceeds via aza-Breslow intermediates. The NHC-catalyzed intramolecular cyclization of aldimines bearing a Michael acceptor resulted in the formation of biologically important 2-(hetero)aryl indole 3-acetic-acid derivatives in moderate to good yields. The carbene generated from the bicyclic triazolium salt was found to be efficient for this transformation.
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.|Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India.
authors.forename: Atanu
authors.initials: A
authors.lastname: Patra
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.|Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India.
authors.forename: Subrata
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.|Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India.
authors.forename: Tamal Kanti
authors.initials: TK
authors.lastname: Das
authors.affiliation: Physical/Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.
authors.forename: Shailja
authors.initials: S
authors.lastname: Jain
authors.affiliation: Centre for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.
authors.forename: Rajesh G
authors.initials: RG
authors.lastname: Gonnade
authors.affiliation: Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-, 411008, India.|Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110020, India.
authors.forename: Akkattu T
authors.identifier: 0000-0002-0645-8261
authors.initials: AT
authors.lastname: Biju
keywords: N-heterocyclic carbenes; imines; indoles; organocatalysis; umpolung