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 dont require further purification.