potassium tert-butylate; triphenylphosphine in tetrahydrofuran Kinetics; -78°C, slow warming to room temp. over 4 h; solvent removal, extn. with Et2O, then THF, residue is Pd compd., extracts are concd., recrystn. of ppt. give phosphorane, kinetics is followedby (1)H NMR;