685089-19-4Relevant articles and documents
Enantiodivergent Preparation of Optically Active Oxindoles Having a Stereogenic Quaternary Carbon Center at the C3 Position via the Lipase-Catalyzed Desymmetrization Protocol: Effective Use of 2-Furoates for Either Enzymatic Esterification or Hydrolysis
Akai, Shuji,Tsujino, Toshiaki,Akiyama, Emi,Tanimoto, Kouichi,Naka, Tadaatsu,Kita, Yasuyuki
, p. 2478 - 2486 (2007/10/03)
Both enantiomers of oxindoles 2a-h, having a stereogenic quaternary carbon center at the C3 position and a different N-protective group, were readily prepared by the lipase-catalyzed desymmetrization protocol. Thus, the transesterification of the prochiral diols 3a-h with 1-ethoxyvinyl 2-furoate 5 was catalyzed by Candida rugosa lipase to give (R)-(+)-2a-h (68-99% ee), in which the use of a mixed solvent, {%N}i{%N}Pr2O (diisopropyl ether)-THF, was crucial. The same lipase also effected the enantioselective hydrolysis of the difuroates 4a-h in a mixture of {%N}i{%N}Pr2O, THF, and H2O to provide the enantiomers (S)-(-)-2a-h (82-99% ee). The products 2 obtained by both methods were stable against racemization. These enzymatic desymmetrization reactions were also applicable for other typical symmetrical difuroates 12b and 15b to provide the racemization-resistant products 13b and 16b.
