Highly regio- and stereoselective 1,3-dipolar cycloaddition of stabilised azomethine ylides to 3,3,3-trihalogeno-1-nitropropenes: synthesis of trihalomethylated spiro[indoline-3,2'-pyrrolidin]2-ones and spiro[indoline-3,3'-pyrrolizin]-2-ones

Reactions of 3,3,3-trihalogen-1-nitropropenes with N-alkyl-alpha-amino acids (sarcosine, proline) and isatins proceed regio- and diastereoselectively to give a wide range of trihalomethylated spiro[indoline-3,2'pyrrolidin]-2-ones and spiro[indoline-3,3'-pyrrolizin]-2-ones in good yields as a result of a 1,3-dipolar cycloaddition of the intermediate stabilised azomethine ylide at the double bond of the nitroalkenes. (C) 2016 Elsevier Ltd. All rights reserved.