Quinidine Thiourea-Catalyzed Aldol Reaction of Unactivated Ketones: Highly Enantioselective Synthesis of 3-Alkyl-3-hydroxyindolin-2-ones
作者:Qunsheng Guo、Mayur Bhanushali、Cong-Gui Zhao
DOI:10.1002/anie.201004161
日期:2010.12.3
New catalysis mechanism! The asymmetricaldolreaction of unactivated ketones and activated carbonyl compounds is realized with a quinidine‐derived thiourea catalyst (see scheme), and involves an enolate mechanism instead of the widely used enamine mechanism. With isatins as the substrate, the reaction can be applied to the enantioselective synthesis of biologically active 3‐hydroxyindolin‐2‐ones.
Enantioselective aldol reactions of isatins with acetone using phthalimido-prolinamide organocatalyst 1 are described. The protocol was effective under solvent free and additive free reaction conditions with 20 mol % of 1 leading to the desired aldol products in good yields and with good enantioselectivities. (C) 2015 Elsevier Ltd. All rights reserved.