.alpha.-(Triphenylphosphoranylidene)-.gamma.-butyrolactone .gamma.-Butyrolactonylidene triphenyl phosphorane 2(3H)-Furanone, 3-(triphenylphosphoranylidene)- 2(3H)-Furanone, dihydro-3-(triphenylphosphoranylidene)- 2-(Triphenylphosphoranylidene)-.gamma.-butyrolactone 34932-07-5 NSC100769