Abstract
A one-pot synthesis of functionalized benzofurans has been developed via O-alkylation, carbon–carbon coupling/cyclization, and dehydration/olefination tandem reactions from phenacyl bromide and phenols under microwave irradiation and solvent-free conditions in the presence of mineral-supported reagent and inorganic base. The best selectivity for forming benzofuran product has been achieved with Na2CO3 as a base. The order of activity of inorganic base is as follows: K2CO3 > NaHCO3 > Na2CO3 > KHCO3 > Na2SO3 > KOH > K3PO4 > NaOH > KH2PO4 > KOAc. This novel synthesis features three new bonds and one ring system assembled in a single step.
ACKNOWLEDGMENT
We are grateful for the financial support of the National Natural Science Foundation of China (NSFC 20773055 and 20021001).
Notes
a Isolated yield.
Note. Reaction conditions: phenacyl bromide, 995 mg (5 mmol); naphthalene (5 mmol); inorganic base (2.5 mmol); and Al2O3 (5.2 g).
a Isolated yield.
Note. Reaction conditions: phenacyl bromide (5 mmol); naphthalene (5 mmol); K2CO3; 350 mg (2.5 mmol); MSR (5.2 g).
a Isolated yield.
Note. Reaction conditions: phenacyl bromide (5 mmol); naphthalene (5 mmol); Al2O3 (5.2 g).
a Isolated yield.
b CEM Discover instrument using an open vessel.
Note. Reaction conditions: phenacyl bromide, 995 mg (5 mmol); naphthalene (5 mmol); Al2O3 (5.2 g); K2CO3, 350 mg (2.5 mmol).
a Isolated yield.
Note. Reaction conditions: phenacyl bromide, 995 mg (5 mmol); phenols (5 mmol); Al2O3 (3 equivalents of substrate, w/w).