Imperial Chemical Industries Limited

Ronald Platt

David R Brittain

Geoffrey R Bedford

The invention concerns a novel process for the racemization of unwanted enantiomeric forms of 1'-substituted spiro[imidazolidine-4,3'-indoline]-2,2',5-triones and 1'-substituted spiro[pyrrolidine-3,3'-indoline]-2,2',5-triones which comprises heating an unwanted enantiomeric form (or a mixture containing an excess of one enantiomer over the other) alone or, more conveniently, in the presence of a solvent or diluent at a temperature in the range 80.degree. to 280.degree. C.

Process for resolving certain spiro compounds

The invention concerns a novel process for the racemisation of unwanted enantiomeric forms of 1'-substituted spiro[imidazolidine-4,3'-indoline]-2,2',5-triones and 1'-substituted spiro[pyrrolidine-3,3'-indoline]-2,2',5-triones which comprises heating an unwanted enantiomeric form (or a mixture containing an excess of one enantiomer over the other) alone or, more conveniently, in the presence of a solvent or diluent at a temperature in the range 80.degree. to 280.degree. C.

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Macclesfield, United Kingdom

Ronald Platt