dbu promoted multi-component domino reactions for synthesis of benzofurans in water

an efficient three-component strategy for the preparation of fused 2,3-dihydrofuran derivatives was developed with the assistance of n-hetocyclic compound ylide. the synthesis was achieved by reacting phenacyl bromides, nheterocycles, aromatic aldehydes and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of dbu (1,8-diazabicyclo (5.4.0) undec-7-ene) as an inexpensive, impressive and readily available catalyst in water under reflux. this strategy provides a rapid and efficient methodology for the preparation of benzofurans in excellent chemo-, regio- and stereoselectivities. this protocol has the advantages of convenient one-pot operation, short reaction times, high isolated yields of the pure products, easy work-up and avoidance of hazardous or toxic catalysts and organic solvents. furthermore, it can be considered as environmentally friendly.