Development approaches towards a 4-spiro cyclopropane proline scaffold (S)-5-(tert-butoxycarbonyl)-5-azaspiro[2.4]heptane-6-carboxylic acid

摘要

The spiro cyclopropyl proline derivative (S)-5-(tert-butoxycarbonyl)-5-azaspiro[2.4]heptane-6-carboxylic acid (1) is a key intermediate in the synthesis of active pharmaceutical compounds. An overview of our synthetic investigations will be presented herein. Three potential approaches have been identified: (a) starting from cyclopropyl-1,1-dimethanol from which the racemic amino acid can be built and then resolved, (b) starting from a pyroglutamic acid or (c) hydroxyproline building block where the spiro cyclopropyl ring has to be formed.