Synthesis of warfarin

Warfarin is an oral anticoagulant, a vitamin K antagonist, widely used to prevent thrombosis; it has also been used as a rodenticide. It was synthesized at the University of Wisconsin (hence its name: Wisconsin Alumni Research Foundation + coumarin).

Its synthesis is a Michael addition: the strongly acidic enol of 4-hydroxycoumarin adds to benzylideneacetone, and the new stereocentre is formed without control (commercial warfarin is racemic). The enantioselective version has been achieved with chiral amine catalysts.