Alcohol-mediated isocyanide domino reactions toward the synthesis of 2-aminofuronaphthoquinones.

An unprecedented alcohol-mediated formation of 2-amino-naphtho[2,3-b]furan-4,9-dione derivatives from 2-hydroxy-1,4-naphthoquinones and isocyanides under microwave irradiation in the presence of Yb(OTf)3 is reported. The effect of different alcohol media, isocyanides and substituted naphthoquinones on the reaction was investigated. A plausible mechanism of this domino transformation involves a conjugate addition of a hemiacetal species to the naphthoquinone to generate an ether intermediate, followed by isocyanide addition and evolution of the corresponding intermediate by intramolecular cyclization. This methodology represents an alternative approach for access to this interesting class of compounds.