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
作者:Shuji Akai、Toshiaki Tsujino、Emi Akiyama、Kouichi Tanimoto、Tadaatsu Naka、Yasuyuki Kita
DOI:10.1021/jo035749h
日期:2004.4.1
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, iPr2O (diisopropyl ether)−THF, was crucial. The same lipase also effected the
羟吲哚2a - h的两个对映异构体均具有C3位置的立体异构季碳中心和不同的N保护基,可通过脂肪酶催化的脱对称化方案轻松制备。因此,通过手性假丝酵母脂肪酶催化前手性二醇3a - h与1-乙氧基乙烯基2-糠酸酯5的酯交换反应,得到(R)-(+)- 2a - h(68-99%ee)。的混合溶剂中,我Pr 2 O(二异丙醚)-THF至关重要。相同的脂肪酶还影响了i的混合物中二糠酸酯4a - h的对映选择性水解。Pr 2 O,THF和H 2 O提供对映体(S)-(-)- 2a - h(82-99%ee)。通过两种方法获得的产物2对于外消旋是稳定的。这些酶促去对称化反应也可用于其他典型的对称二糠酸酯12b和15b,以提供抗消旋作用的产物13b和16b。