BF3·OEt2-promoted concise synthesis of difluoroboron-derivatized curcumins from aldehydes and 2,4-pentanedione

A concise and one-pot cascade method has been developed to achieve the synthesis of difluoroboron-derivatized curcumins (BF2C). Treatment of 2,4-pentanedione with BF3·OEt2, followed by condensation with aldehydes in the presence of tributyl borate and butylamine at 65 °C in toluene furnished the corresponding symmetric (s-BF2C) and unsymmetric difluoroboron-derivatized curcumins (us-BF2C) in good (60-99%) and moderate yields (23-42%) within 6-12 h, respectively.