Cs2CO3-Mediated Rapid Room-Temperature Synthesis of 3-Amino-2-aroyl Benzofurans and Their Copper-Catalyzed N-Arylation Reactions

摘要

Cs_(2)CO_(3) in dimethylformamide (DMF) is a perfect combination for the rapid room-temperature synthesis of 3-amino-2-aroyl benzofuran derivatives from the reaction of 2-hydroxybenzonitriles and 2-bromoacetophenones in good to excellent yields. Using this one-pot C–C and C–O bond-forming strategy, we prepared a series of 3-amino-2-aroyl benzofuran derivatives within a very short time (10–20 min). This method was also found suitable for gram-scale synthesis. Benzofurans (3 ) obtained by this Cs_(2)CO_(3)-mediated methodology were then further explored for the development of a tunable base- and ligand-free copper-catalyzed N -arylation methodology using arylboronic acids for the easy access of either mono- or bi-N -aryl derivatives of aminobenzofurans at ambient temperature. The reaction of 3 with malononitrile in DMF medium under microwave heating conditions provided highly fluorescent conjugated alkenes and novel pyridine-fused benzofurans.