Highly enantioselective synthesis of 3-amino-2-oxindole derivatives: catalytic asymmetric alpha-amination of 3-substituted 2-oxindoles with a chiral scandium complex.
A highly enantioselective alpha-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by a chiral Sc(OTf)(3)/N,N'-dioxide complex (Tf: triflate) has been developed and affords the corresponding 3-amino-2-oxindole derivatives in high yields (up to 98%) with excellent enantioselectivities (up to 99% ee). The procedure is capable of tolerating a relatively wide range of substrates, and excellent results (92-96% ee) can also be obtained, even in the presence of 0.5 mol % of catalyst loading under mild conditions. These results showed the potential value of the catalytic approach. Moreover, with high synthetic versatility, the product could be easily transformed into optically active 3-amino-3-methyloxindole bearing a chiral quaternary stereogenic center.
Yang
Zhigang
Z
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, PR China.
Wang
Zhen
Z
Bai
Sha
S
Shen
Ke
K
Chen
Donghui
D
Liu
Xiaohua
X
Lin
Lili
L
Feng
Xiaoming
X
D000586:Amination; D002384:Catalysis; D018360:Crystallography, X-Ray; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D000078183:Oxindoles; D012538:Scandium / Q000737:chemistry*; D013237:Stereoisomerism
C551521:3-amino-2-oxindole; D007211:Indoles; D009942:Organometallic Compounds; D000078183:Oxindoles; C022960:2-oxindole; D012538:Scandium