Nucleophilic substitutions at the phosphonium or phosphoryl centres of 2, 2, 3, 4, 4- pentamethylphosphetans proceed with retention of configuration at the phosphorus. 1-Aryl- 2, 2, 3, 4, 4-pentamethylphosphetan oxides when treated with aryl-lithiums give aryl-(3-aryl- 1, 1, 2, 3, 3-pentamethylpropyl) phosphine oxides. Additional evidence, involving deuterium labelling, is presented for the spirocyclohexa-1, 4-diene structure (III) for the oxide from the ...
