Process for the enantioselection synthesis of alkylated oxindoles used as intermediates in the preparation of physostigmine

Abstract From the Canadian patent

Process for the enantioselection synthesis of alkylated oxindoles used as intermediates in the preparation of physostigmine, A process for the stereoselective synthesis of R- and S-2,3-dihydro-1,3-dimethyl-2-oxo-1H-indole-3-acetonitriles comprises reacting racemic and 5-alkoxy-substituted (?)-1,3dimethyloxindoles with a halogenated acetonitrile in the presence of a substituted N-benzyl cinchoninium quinidinium, cinchonidinium, or quininium catalyst. The resulting alkylated oxindoles can be converted to primary amines by catalytic reduction in the presence of hydrogen gas. One of the primary amines, such as enantiomers of 3-(2-aminoethyl)- 1,3-dihydro-1,3-dimethyl-5-methoxy-2H-indol-2-one …