A concise synthesis of highly functionalized α,β-unsaturated γ-butyrolactones through ring contraction of 2H-pyran-2-ones

2-Oxo-5-(1-arylvinyl)-4-piperidin-1-yl-2,5-dihydrofuran-3-carbonitriles 3 have been synthesized through ring contraction of suitably functionalized 2H -pyran-2-ones 1 by a carbanion generated in situ from nitromethane 2 in good yield. In some cases their counterpart tautomers 2-oxo-5-(1-arylethylidene)-4-piperidin-1-yl-2,5-dihydrofuran-3-carbonitriles 4 have also been isolated and characterized as minor products.