Synthesis and reactions of phosphino- and phosphono substituted-coumarins

Abstract

Aminophosphine-ylides 4a and 4b were prepared in high yields by treating 3-acetyl coumarins 1a and 1b with trisdimethylaminophosphine 2. Chemical degradation reactions for the ylides 4a, b (e.g., formation of the phosphonium salt, Wittig reaction, hydrolysis) were suggested and illustrated. Reaction of trialkyl phosphites with 3-acetyl coumarins 1a and 1b yields the respective dialkyl phosphonates (1:4 addition) 12a, b. Conversely, dialkyl phosphonates react with the same species 1a, b to give the tautomeric monophosphonates 17A 17B via both 1,4- and 1,2 additions, in contrast to earlier reports.