title: Phase-transfer-catalysed synthesis of pyrroloindolines and pyridoindolines by a hydrogen-bond-assisted isocyanide cyclization cascade.
abstract: A cascade reaction that generates pyrrolo- and pyridoindoline motifs from isocyanide precursors under phase-transfer conditions is described. This transformation proceeds at room temperature in the presence of a quaternary ammonium catalyst and base to generate functionalized products containing an all-carbon quaternary stereocentre. Quantum chemical calculations demonstrated that intramolecular general acid catalysis plays a key accelerating role through stabilization of developing charge in the transition state, and that the reaction is best described as a 5-endo dig cyclization, rather than an anionic 6π electrocyclization. Investigations employing chiral phase-transfer catalysts have given promising selectivities to date.
authors: Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA (UK).
authors: Peter C
authors: PC
authors: Knipe
authors: Matija
authors: M
authors: Gredičak
authors: Artiom
authors: A
authors: Cernijenko
authors: Robert S
authors: RS
authors: Paton
authors: Martin D
authors: MD
authors: Smith
mesh_terms: D002384:Catalysis; D003486:Cyanides / Q000737:chemistry*; D003500:Cyclization; D006860:Hydrogen Bonding; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D044367:Phase Transition; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: D003486:Cyanides; D007211:Indoles; D011725:Pyridines; D011758:Pyrroles
keywords: cascade reactions; density functional calculations; heterocycles; hydrogen bonds; isocyanides; phase-transfer catalysis