N′-Phenyl-and methyltrifluoroacetohydrazides react with phosphorus pentachloride to give the corresponding 2, 2, 2-trichloro-3-phenyl-and methyl-Δ 4-1, 3, 4, 2-oxadiazaphospholines , from which various 2, 2, 2-trisubstituted derivatives are further synthesized. Heating 3- phenyl-2, 2, 2-tris (p-tolyloxy) analog with an excess of styrene affords 1, 5-diphenyl-3- trifluoromethyl-2-pyrazoline, which indicates that the phospholine behaves as a precursor ...