Combining cycloaddition reactions for the one-pot synthesis of novel xanthoquinone dyes

Xanthoquinones, as a new class of quinone dyes comprising the xanthone and quinone subunits have been synthesized. An elusive aminofurochromone as an electron-rich diene was generated in situ from the corresponding chromone-3-carbaldehyde and alkyl or aryl isocyanide via a formal [4 + 1] cycloaddition reaction, then engaged by p-quinone partner (1,4-benzoquinone or 1,4-naphthoquinone) as an electron-deficient dienophile to afford the desired novel xanthoquinone dye via a [4 + 2] cycloaddition/ring opening/dehydrative aromatization sequence.