A Convenient Synthesis of a Simple Coumarin from Salicylaldehyde and Witting Reagent (I): A Synthesis of Methoxy- and Hydroxycoumarins

Abstract

Reaction of methoxy-and hydroxysalicylaldehydes (1) with phosphorane in diethylaniline under reflux gave only wumarins (3) in high yields except for 3-methoxysalicylaldehy& (lb).It was clarified that methoxy group(s) at Cq and Cg on 1 facilitated the formation of 3. Coumarins are widely distributed in nature1 and have been reporled to show various biologically interesting activitie~.~Although many synthetic methais to coumarins, especially to simple (3,4-unsubstituted) coumarins including the Perkin, Knoevenagel, and Pechmann reactions, are h ~o w n , ~