Dihydrofurocoumarin and dihydrofurodihydropyrid-2-one derivatives via palladium catalysed cascades involving aryl/heteroaryl/vinyl iodides and allene followed by acid catalysed cyclisation

Mono 3-(2′-arylallyl) derivatives of 4-hydroxycoumarin 1a,b , 4-hydroxy-6-methyl-pyran-2-one ( 3 ) and 6-hydroxy-1,4-dimethyl-1,2-dihydropyrid-2-one-3-carbonitrile ( 4 ) are produced in 3-component cascades involving aryl/heteroaryl/vinyl iodides and allene (1 atm) using Pd(PPh3)4/Cs2CO3/MeCN/80 °C or Pd2(dba)3/tris(2-furyl)phosphine/K2CO3/DMF/80 °C as the catalyst system. 4-Hydroxy-2-quinolone ( 2 ) afforded a mixture of mono- and bis-allylation products under these conditions. Mono C-allylation products 5a–e and 15a–e undergo facile acid catalysed cyclisation to afford dihydrofurocoumarins 11a–e and dihydrofurodihydropyrid-2-ones 16a–e in good overall yield.