Synthesis of Coumarin Derivatives from 4-Oxo-4H-1-benzopyran-3-carboxaldehyde via 3-(Arylaminomethylene)chroman-2,4-dione

K-10 Montmorillonite mediated condensation of aldehyde 1 with arylamine 2 affords chroman-2,4-dione 5 which gives tricoumarol 8 by acid hydrolysis, 4-arylamino-3-formylcoumarin 11 and 1-benzopyrano[4,3-b]quinoline 12 on heating with POCl3.