Asymmetric Synthesis of Spiropyrazolone-Fused Dihydrofuran-naphthoquinones Bearing Contiguous Stereocenters via a Michael Addition/Chlorination/Nucleophilic Substitution Sequence
Gaihui Li, Hong‐Yu Zhang, Guoshun Zhang, Bei Wei, Bin Liu, Heng Song, Qingshan Li, Shurong Ban
Abstract
An enantioselective synthesis of spiropyrazolone-fused dihydrofuran-naphthoquinones is first demonstrated via a Michael addition/Chlorination/Nucleophilic substitution sequence. The reactions of 2-hydroxy-1,4-naphthoquinone and α,β-unsaturated pyrazolones in the presence of the cinchona alkaloid derived hydrogen-bonding catalyst and NCS provide spiropyrazolone-fused 2,3-dihydronaphtho[2,3- b ]furan-4,9-diones bearing contiguous stereocenters, of which one is the spiro quaternary stereocenter in high yields with exclusive diastereoselectivity and good to excellent enantioselectivities.
Topics & Concepts
StereocenterEnantioselective synthesisCinchonaChemistryMichael reactionNucleophilic substitutionStereochemistryFuranNucleophileSequence (biology)Hydrogen bondCatalysisOrganic chemistryMoleculeBiochemistryBioactive Compounds and Antitumor AgentsOxidative Organic Chemistry ReactionsAsymmetric Synthesis and Catalysis