Copper(II)-catalyzed oxidative ipso -annulation of N -arylpropiolamides and biaryl ynones with 1,3-diketones: construction of diketoalkyl spiro-trienones.

An unprecedented copper-catalyzed ipso -annulation reaction of N -( p -methoxyaryl)propiolamides with 1,3-diketones has been developed, which enables the assembly of diketoalkylated spiro[4.5]trienones involving oxidative dearomatization in the presence of ammonium persulfate [(NH 4 ) 2 S 2 O 8 ] as the oxidant. This protocol was extended to biaryl ynones, efficiently affording the diketoalkylated spiro[5.5]trienones in good yields. The significance of the diketoalkyl functionality has been illustrated by further transformation into 3-pyrazoyl spiro-trienone, a structurally unique motif.