An efficient synthesis of phthalides by Diels-Alder reaction of sulfur-substituted furanones with silyloxydienes: A formal synthesis of mycophenolic acid.
Highly substituted phthalides including a key intermediate in the synthesis of mycophenolic acid were prepared by the Diels-Alder reaction of 3-(phenylthio- or 3-(phenylsulfinyl)-2-(5H)-furanones with silyloxydienes.