The crystal structure of a Wittig intermediate containing a fourmembered ring. 4,4-Bis(trifluoromethyl)2,2,2-triphenyl-3-(triphenyl-phosphoranylidene)-1,2-oxaphosphetane

Abstract

4,4-Bis(trifluoromethyl)-2,2,2-triphenyl-3-(triphenylphosphoranylidene)-1,2-oxaphosphetane (I) is monoclinic, space group P2₁/n with a= 19·72, b= 11·54, c= 16·98 Å, and β= 117° 45′. The compound is produced from the reaction of Ph₃P:C:PPh₃ and (CF₃)₂CO and contains a planar 4-membered heterocyclic ring system with a long P–O bond of 2·01 Å. The bonds from the phosphorus atoms to the heterocyclic ring carbon atom are essentially equal (1·76, 1·75 Å). The final R-factor for 1708 three dimensional reflexions is 0·123.