CDC Reaction and Subsequent Cyclization for the Synthesis of 2-Hydroxy-3-alkyl-1,4-naphthoquinones and Pyranonaphthoquinones

The metal-free cross-dehydrogenative coupling (CDC) reaction and subsequent cyclization of 2-hydroxy-1,4-naphthoquinone (lawsone) and 1,3-diarylpropene promoted by DDQ has been developed. 2-Hydroxy-3-alkyl-1,4-naphthoquinones and pyranonaphthoquinones with potential pharmaceutical applications are obtained in moderate to good yields. The reaction is also compatible for 4-hydroxycoumarins.