| Popis: |
A highly efficient stereoselective method for the synthesis of functionalized spirooxindole derivatives with four contiguous stereogenic centers, including two adjacent quaternary stereogenic centers, was realized through an organocatalytic tandem Michael–Michael reaction. By employing a quinidine-derived thiourea organocatalyst, the reaction between (E)-2-cyano-2-(2-oxo-1-tritylindolin-3-ylidene)acetates and (E)-1-alkyl-6-nitro-hex-2-en-1-ones yields the desired spirooxindole products in good yields (up to 90%) and with excellent stereoselectivities (up to 95:5 dr and 98% ee). |
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