title: Chiral Brønsted base-promoted nitroalkane alkylation: enantioselective synthesis of sec-alkyl-3-substituted indoles.
abstract: A Brønsted base-catalyzed reaction of nitroalkanes with alkyl electrophiles provides indole heterocycles substituted at C3 bearing a sec-alkyl group with good enantioselectivity (up to 90% ee). Denitration by hydrogenolysis provides a product with equally high ee. An indolenine intermediate is implicated in the addition step, and surprisingly, water cosolvent was found to have a beneficial effect in this step, leading to a one-pot protocol for elimination/enantioselective addition using PBAM, a bis(amidine) chiral nonracemic base.
authors.affiliation: Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235-1822, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Dobish
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Johnston
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D000478:Alkylation; D002384:Catalysis; D006571:Heterocyclic Compounds / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis*; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000473:Alkanes; D006571:Heterocyclic Compounds; D007211:Indoles; D009574:Nitro Compounds