Organo-phosphorus compounds S 0080Unusual Reaction of 8-Chloro-2-cyclohexyl-4-phenylbenzo[e]-1,2-oxaphosphinine-2-oxide with Tetramethylenebis(magnesium bromide). -The reaction of title compound (III) with Grignard reagents (IV) and (VI) provides a versatile approach to the synthesis of unsymmetrical phosphine oxides. The chiral phosphorus atom in (III) is capable of reacting with Grignard reagents to afford phosphine oxides (V) with three different substituents through the cleavage of the oxaphosphine heterocycle. The reaction of (III) with tetramethylenebis(magnesium bromide) (VI) results in the formation of diphosphine oxide derivative (VII) and the unexpected formation of spirophosphorane (VIII). -(TATARINOV, D. A.; MIRONOV*, V. F.; VARAKSINA, E. N.; KRIVOLAPOV, D. B.; LITVINOV, I. A.; MUSIN, R. Z.; BUZYKIN, B. I.; KONOVALOV, A. I.; Mendeleev