a one-pot condensation for synthesis 2-methyl-4-phenylpyrano[3, 2-c] chromen-5(4h)-one and synthesis of warfarin by ionic liquid catalysis

the anticoagulant racemic warfarin is synthesized by the michael addition of 4-hydroxycoumarin with benzalacetone in the present of equimolar amounts of imidazolium based ionic liquids [bmim] bf4 and [bmim] br and other reaction solvents such as h2o, pyridine and ammonia in five different tests. also synthesis of a derivative of warfarin (2-methyl-4-phenyl pyrano [3, 2-c] chromen-5(4h)-one) under solvent-free condition is reported. in this paper, we show the potential that ionic liquid have for the development of green methods for the formation of the c-c bond by reaction condensations without catalysts and organic solvents. a ،green method, according to the well-known principles, must reduce or eliminate the use or generation of unsafe substances. the work-up procedures were fairly simple and the products don't require further purification.