Catalytic asymmetric synthesis of 3-aminooxindoles: enantiofacial selectivity switch in bimetallic vs monometallic Schiff base catalysis.
A highly enantioselective catalytic asymmetric access to 3-aminooxindoles with a tetrasubstituted carbon stereocenter is described. 1-2 mol % of homobimetallic (R)-Ni(2)-Schiff base 1 catalyzed the asymmetric amination of 3-substituted oxindoles with azodicarboxylates to give (R)-products in 99-89% yield and 99-87% ee. Reversal of enantiofacial selectivity was observed between bimetallic and monometallic Schiff base complexes, and monometallic (R)-Ni-Schiff base 2c gave (S)-products in 98-80% ee. Transformation of the products into an optically active oxindole with a spiro-beta-lactam unit and a known key intermediate for AG-041R synthesis is also described.
Mouri
Shinsuke
S
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Chen
Zhihua
Z
Mitsunuma
Harunobu
H
Furutachi
Makoto
M
Matsunaga
Shigeki
S
Shibasaki
Masakatsu
M
D000586:Amination; D002384:Catalysis; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D000078183:Oxindoles; D012545:Schiff Bases / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
C109755:AG-041R; D007211:Indoles; D000078183:Oxindoles; D012545:Schiff Bases; C022960:2-oxindole