This work is dedicated to Professor K. C. Majumdar, Department of Chemistry, Kalyani
University, West Bengal, India on the occasion of his 68th birthday.
Abstract
A wide variety of fused trans-2,3-dihydrofuran derivatives were synthesized through a one-pot three-component reaction
of an aromatic aldehyde, a cyclic β-diketo compound, and an in situ-generated pyridinium ylide in refluxing. The pyridinium ylide was formed from either
2-bromo-1-phenylethanone or 4-nitrobenzyl bromide and pyridine in the presence of
10 mol% of sodium hydroxide. Pyridine plays crucial role in forming the pyridinium
salt, which, in turn, forms a nitrogen ylide in the presence of sodium hydroxide.
The ylide assists a Michael-initiated ring-closure reaction, but is not itself incorporated
in the final product. The protocol is environmentally acceptable because no organic
solvent is involved at any stage. Furthermore, the method is highly diastereoselective,
gives good yields, and does not involve extensive workup procedures or chromatographic
separations, as the desired products can be isolated by filtration and drying.
Key words
furans - heterocycles - cyclizations - multicomponent reactions - green chemistry
- regioselectivity - diastereoselectivity
