Synthesis And Structure Confirmation Of Nitrogen-containing Heterocycles Derived From Propioamides With DBU(DBN)

1,8-Diazacyclo[5,4,0]undec-7-ene?DBU?and1,5-dizazcyclo[4,3,0]non-5-ene?DBN?are widely utilized as non-nucleophilic strong bases in various reactions such as elimination reactions,isomerizations,condensations and cyclizations,etc.However,more and more reports have demonstrated that both DBU and DBN can act as nucleophiles.Phenylpropiolamide compounds,which prepared from cinnamates through bromination,elimination and amidation,react with DBU or DBN to give different nitrogen-containing heterocycles.The structures were carried out by nuclear magnetic resonace spectrometry(¹H NMR,¹³C NMR,DEPT 135,H-H COSY,HSQC,HMBC,NOESY)and mass spectrometry.Three possible mechanisms were proposed subsequently:DBU and DBN played double roles of C,N-nucleophiles in forming products ? and ?,and act as N-nucleophiles in yielding products ? with H₂O.