Highly efficient chemoselective construction of 2,2-dimethyl-6-substituted 4-piperidones via multi-component tandem Mannich reaction in ionic liquids

The room temperature ionic liquid [bmim][PF6] has been demonstrated to be an efficient and recyclable medium for highly chemoselective synthesis of 2,2-dimethyl-6-substituted 4-piperidones via a L-proline catalyzed tandem Mannich reaction of ammonia, aldehydes and acetone, and good yields were achieved for aryl and alkyl aldehydes.