Highly diastereroselective synthesis of dihydrofurans and dihydropyrroles via pyridine catalyzed formal [4+1] annulationElectronic supplementary information (ESI) available: General synthesis procedures and NMR data of compounds. See DOI: 10.1039/c0cc02347g

A pyridine-catalyzed ylide cyclization affording dihydrofurans and dihydropyrroles has been developed. In the presence of a catalytic amount of pyridine and Fe(Tcpp)Cl, α-ylidene-β-diketones and α,β-unsaturated imines react with diazoacetates providing dihydrofurans and dihydropyrroles respectively, in up to 96% yield with high diastereoselectivities. A pyridine-catalyzed ylide cyclization has been developed for the synthesis of dihydrofurans and dihydropyrroles in up to 96% yield with high diastereoselectivities.