Spiro Scaffold Chiral Organocatalyst of 3,2′-Pyrrolidinyl Spiro-oxindole Amine and Its Catalytic Evaluation in the Enantioselective Aldol Condensation between 3-(3-Hydroxy-1<i>H</i>-pyrazol-1-yl)-Oxindole and Paraformaldehyde
Ying Zou, Zhicheng Huang, Min Xiang, Chenyi Li, Xia Li, Fang Tian, Li-Xin Wang
Abstract
The spiro scaffold chiral organocatalyst of 3,2′-pyrrolidinyl spiro-oxindole amine was successfully prepared from racemic spiro-oxindole amine using l -menthol as a chiral pool in 4 steps in 28%–40% overall yields with at least 99% ee in scale-up preparation, and its catalytic activity was evaluated in the enantioselective aldol condensation between 3-(3-hydroxy-1 H -pyrazol-1-yl)-oxindole and paraformaldehyde. The spiro organocatalyst showed superior catalytic activity and selectivity compared with its counterparts, and most substrates offered good to excellent results with up to 96% yield in 96% ee.
Topics & Concepts
ChemistryOxindoleEnantioselective synthesisAldol condensationAmine gas treatingParaformaldehydeCatalysisOrganic chemistryAldol reactionYield (engineering)SelectivityOrganocatalysisCombinatorial chemistryMaterials scienceMetallurgyAsymmetric Synthesis and CatalysisChemical Synthesis and ReactionsChemical Synthesis and Analysis