An organocatalytic enantioselective N-nitroso-aldol reaction of 2-oxindoles promoted by a cinchona alkaloid catalyst has been developed. The reaction shows exclusively N-selectivity, affording corresponding products with good to excellent yields (up to 100%) and moderate enantioselectivity. The regioselectivity of nitroso-aldol reaction being controlled by different cinchona catalysts was also observed. (C) 2010 Elsevier Ltd. All rights reserved.
Facile and Efficient Enantioselective Hydroxyamination Reaction: Synthesis of 3-Hydroxyamino-2-Oxindoles Using Nitrosoarenes
Sc takes action: The highly enantioselectivehydroxyaminationreaction of N‐unprotected 2‐oxindoles with nitrosoarenes has been realized using the Sc(OTf)3/L1 complex. The catalyst system exhibited remarkably broad substrate scope and high efficiency. This transformation is the first example of a chiral ScIII/enolate activating a nitrosoarene, and can be conducted on a gram scale without loss in the
Sc发挥作用:使用Sc(OTf)3 / L1络合物实现了N-未保护的2-氧吲哚与亚硝基芳烃的高度对映选择性羟基胺化反应。该催化剂体系表现出显着的底物范围和高效率。该转化是手性Sc III /烯酸酯活化亚硝基芳烃的第一个实例,并且可以以克级进行,而不会损失ee 值。
Enantioselective organocatalytic oxyamination of unprotected 3-substituted oxindoles
An enantioselective α-oxyamination of unprotected 3-substituted oxindoles with nitrosobenzene catalyzed by tertiary amine–thiourea bifunctional organocatalysts has been developed and affords the corresponding 3-amino-2-oxindole derivatives in good yields and with moderate to excellent enantioselectivities (up to > 99.9 : 0.1 er when the product is isolated by direct filtration from the reaction mixture)