1438263-83-2Relevant articles and documents
L-tert-Leucine derived urea-ammonium salts: Efficient bifunctional phase transfer catalysts for highly diastereo- and enantioselective aza-Henry reaction of isatin-derived N-Boc ketimines with α-aryl nitromethanes
Wang, Jingdong,Liu, Yu,Liu, Yuxin,Wei, Zhonglin,Cao, Jungang,Liang, Dapeng,Lin, Yingjie,Duan, Haifeng
, p. 2883 - 2892 (2019)
An efficient way of aza-Henry reaction between isatin-derived N-Boc ketimines and α-aryl nitromethanes catalyzed by bifunctional phase transfer catalysts with a quaternary ammonium center derived from L-tert-Leucine has been developed. A series of 3-substituted 3-amino-oxindoles were constructed by this catalytic protocol in excellent yields (90–99%), with high enantioselectivities (83–95%)and diastereoselectivities (79:21–97:3). The asymmetric aza-Henry reaction of N-Boc amidosulfones and α-aryl nitromethanes were also investigated and gave the corresponding products in high to excellent yields (72–97%)with high enantioselectivities (up to 99%)and diastereoselectivities (up to >99:1).
Novel bifunctional thiourea-ammonium salt catalysts derived from amino acids: Application to highly enantio- and diastereoselective aza-Henry reaction
Wang, Hong-Yu,Chai, Zhuo,Zhao, Gang
, p. 5104 - 5111 (2013/06/27)
The development of new efficient and easily accessible catalysts has been one of the focuses in asymmetric phase-transfer catalysis. In this paper, a novel class of chiral bifunctional thiourea-ammonium phase-transfer catalysts were synthesized from commercially available α-amino acids. The structural modularity of these catalysts permits facile tunings to achieve optimum results, which was demonstrated in catalyzing the aza-Henry reaction with excellent enantioselectivities (up to 99.5% ee) and diastereoselectivities (up to >25:1 dr).
