Konda S, Jakkampudi S, Arman HD, Zhao JCG. Enantioselective synthesis of spiro[
4H-pyran-3,3'-oxindole] derivatives catalyzed by cinchona alkaloid thioureas: Significant water effects on the enantioselectivity.
SYNTHETIC COMMUN 2019;
49:2971-2982. [PMID:
33012850 DOI:
10.1080/00397911.2019.1651866]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
An efficient stereoselective three-component reaction for the synthesis of functionalized spiro[4H-pyran-3,3'-oxindole] derivatives was realized through an organocatalyzed domino Knoevenagel/Michael/cyclization reaction using a cinchonidine-derived thiourea as the catalyst. Using water as the additive was found to improve the product ee values significantly. Under the optimized conditions, the reactions between isatins, malononitrile, and 1,3-dicarbonyl compounds yield the desired spirooxindole products in good yields (71-92%) and moderate to high ee values (up to 87% ee).
Collapse