Enantioselective Synthesis of Spiropyrazolone-Fused Cyclopenta[<i>c</i>]chromen-4-ones Bearing Five Contiguous Stereocenters via (3+2) Cycloaddition
Pankaj V. Khairnar, Yin-Hsiang Su, Athukuri Edukondalu, Wenwei Lin
Abstract
]chromen-4-ones is demonstrated via a (3+2) cycloaddition reaction. The reactions of 3-homoacylcoumarins and α,β-unsaturated pyrazolones in the presence of the cinchona-alkaloid derived hydrogen-bonding catalyst provide aforementioned spiropyrazolone-chromenone adducts bearing five contiguous stereocenters, of which one is the spiro all-carbon quaternary stereocenter in high yields (up to 98%) with good to excellent stereoselectivities (>25:1 dr and up to 99% ee). This one-pot methodology could also be practically demonstrated on a gram-scale with similar efficacy.
Topics & Concepts
StereocenterEnantioselective synthesisChemistryCycloadditionCinchonaPyrazolonesStereochemistryAdductCatalysisHydrogen bondOrganocatalysisOrganic chemistryMoleculeAsymmetric Synthesis and CatalysisMulticomponent Synthesis of HeterocyclesOxidative Organic Chemistry Reactions