Organocatalytic three-component cascade reaction for the synthesis of spiro[indeno[1,2-b]furan]-triones.

New methods for the synthesis of spiro compounds containing dihydrofuran and coumarin moieties from 3-bromo-4-hydroxycoumarins as cyclic α-halo compound based on a pyridinium-ylide-assisted three-component tandem reaction is investigated. To the best of our knowledge, employing cyclic α-halo compounds for the synthesis of dihydrofuran-fused coumarin via a pyridinium ylide has not been reported yet.