Tandem Blaise-Nenitzescu reaction: one-pot synthesis of 5-hydroxy-a-(aminomethylene)benzofuran-2(3H)-onesfrom nitriles

摘要

In contrast to the reaction of benzoquinones with β-enaminoesters providing indoles (Nenitzescu reaction), the tandem one-pot reaction of the Blaise reaction intermediate, zinc bromide complex of β-enaminoesters, with benzo-quinone affords 5-hydroxy-a-(aminomethylene)benzofuran-2(3H)-ones in good to excellent yields (tandem Blaise-Nenitzescu reaction).