Synthesis and reactions of phosphino- and phosphono substituted- coumarins

Article abstract of DOI:10.1016/S0040-4020(99)00940-0

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 lb yields the respective dialkyl phosphonates (1:4 addition) 12a,b. Conversely, dialkyl phosphonates react with the same species la,b to give the tautomeric monophosphonates 17A?17B via both 1,4- and 1,2 additions, in contrast to earlier reports.