title: Asymmetric synthesis of congested spiro-cyclopentaneoxindoles via an organocatalytic cascade reaction.
abstract: Starting from simple alkylidene oxindoles and nitroketones, a highly stereoselective methodology was developed for the synthesis of spiro-cyclopentaneoxindoles with four consecutive stereogenic centers. Using an organocatalytic cascade of Michael and aldol reactions in the presence of a chiral thiourea catalyst products were obtained in moderate to high yields and excellent enantioselectivities. Nitro, ester, and hydroxyl groups were introduced to the spiro ring, which could be used to facilitate further functionalization of the products.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Artur
authors.initials: A
authors.lastname: Noole
authors.forename: Kaja
authors.initials: K
authors.lastname: Ilmarinen
authors.forename: Ivar
authors.initials: I
authors.lastname: Järving
authors.forename: Margus
authors.initials: M
authors.lastname: Lopp
authors.forename: Tõnis
authors.initials: T
authors.lastname: Kanger
mesh_terms: D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry; D000078183:Oxindoles; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D003517:Cyclopentanes; D007211:Indoles; D007659:Ketones; D009574:Nitro Compounds; D000078183:Oxindoles; D013141:Spiro Compounds; C022960:2-oxindole