title: Palladium-catalyzed asymmetric cycloadditions of vinylcyclopropanes and in situ formed unsaturated imines: construction of structurally and optically enriched spiroindolenines.
abstract: A palladium-catalyzed (3 + 2) cycloaddition of vinyl cyclopropane and α,β-unsaturated imines generated in situ from aryl sulfonyl indoles is reported. The reaction proceeds with high diastereoselectivity to provide the optically enriched spirocyclopentane-1,3'-indolenines in up to 74% yield and with up to 97% ee, which contains an all-carbon quaternary center and two tertiary stereocenters. The reaction involves a first conjugate addition of the carbon anion of zwitterionic π-allylpalladium complex from vinyl cyclopropane to the in situ formed unsaturated imine followed by a palladium-catalyzed intramolecular C3-allylation of indole.
authors.affiliation: Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University , Nanchong 637002, P. R. China.
authors.forename: Ze-Shui
authors.initials: ZS
authors.lastname: Liu
authors.forename: Wen-Ke
authors.initials: WK
authors.lastname: Li
authors.forename: Tai-Ran
authors.initials: TR
authors.lastname: Kang
authors.forename: Long
authors.initials: L
authors.lastname: He
authors.forename: Quan-Zhong
authors.initials: QZ
authors.lastname: Liu
mesh_terms: D002384:Catalysis; D061565:Cycloaddition Reaction; D003521:Cyclopropanes / Q000737:chemistry*; D007097:Imines / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013450:Sulfones / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D003521:Cyclopropanes; D007097:Imines; D007211:Indoles; D013141:Spiro Compounds; D013450:Sulfones; D014753:Vinyl Compounds; D010165:Palladium