Copper(<scp>ii</scp>)-catalyzed oxidative <i>ipso</i>-annulation of <i>N</i>-arylpropiolamides and biaryl ynones with 1,3-diketones: construction of diketoalkyl spiro-trienones

Abstract

An unprecedented copper-catalyzed <i>ipso</i>-annulation reaction of <i>N</i>-(<i>p</i>-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 [(NH₄)₂S₂O₈] 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.