Quinine-Based Trifunctional Organocatalyst for Tandem Aza-Henry Reaction-Cyclization: Asymmetric Synthesis of Spiroxindole-Pyrrolidine/Piperidines
作者:Saumen Hajra、Bibekananda Jana
DOI:10.1021/acs.orglett.7b02150
日期:2017.9.15
A quinine-derived trifunctional sulphonamide catalyst has been developed for the effective asymmetric organocatalytic tandem aza-Henry reaction-cyclization of isatin-derived ketimines and nitroalkane-mesylates for the synthesis of spiro-pyrrolidine/piperidine-oxindoles. Demethylation of traditional bifunctional catalyst to incorporate an additional hydrogen bonding C6′–OH group plays the key role toward
An asymmetric synthesis of N,N′-ketal compounds derived from isatin-derived ketimines and aryl amines has been developed using an inexpensive and readily available L-tert-leucine derived urea catalyst. Using this asymmetric catalytic synthetic method, a series of 3-substituted 3-amino-2-oxoindole derivatives containing an N,N′-ketal motif were obtained in high yields with high enantioselectivities
Highly Enantioselective Synthesis of Acyclic <i>N</i>,<i>N</i>′-Acetals by Chiral Urea Derived from Quinine Catalyzed the Addition of Aryl Amines to Isatin-Derived Ketimines
N,N′-Acetals are sensitive compounds, and the challenging asymmetric synthesis of acyclic N,N′-acetals by the general addition of amines to ketimines has never been reported so far. In this study, highly enantioselective addition of aryl amines to isatin-derived ketimines catalyzed by chiral urea derived from quinine was developed. A series of new acyclic N,N′-acetals were constructed by this protocol
Copper/guanidine-catalyzed asymmetric alkynylation of isatin-derived ketimines
作者:Quangang Chen、Lihua Xie、Zhaojing Li、Yu Tang、Peng Zhao、Lili Lin、Xiaoming Feng、Xiaohua Liu
DOI:10.1039/c7cc08920a
日期:——
Isatin-derived ketimines undergo enantioselective alkynylation reactions in the presence of copper iodide and easily accessible guanidine-amides. The corresponding 3-alkynyl-3-aminooxyindoles are obtained in up to 95% yield and 96% ee. The guanidine plays a role in the formation of copper acetylide and the enantiodetermining step and the basic additive is excluded.
Direct enantio- and diastereoselective Mannich reactions of isatin-derived ketimines with oxo-indanecarboxylates catalyzed by chiral thiourea derived from hydroquinidine
A highly diastereo- and enantioselective Mannich reaction of isatin-derived ketimines with oxo-indanecarboxylates catalyzed by chiral thiourea derived from hydroquinidine has been developed. A series of 3-substituted 3-amino-oxindoles containing assembled bicyclic rings linked by a C–C bond were constructed by this protocol in excellent yields (92–99%) with high enantioselectivities (85–99% ee) and