Evidence of the loss of chirality at the phosphonium step in the arbuzov rearrangement.

Reaction of the diastereomerically pure oxazaphospholidine 3 with alkyl halides was monitored by 1H, 13C, 31P NMR and clearly showed the formation of two phosphonium intermediates with the same diastereomeric ratio as that of the final products. Benzyl halides reacted with 3 yielding a mixture of the two epimers a and b which syncrystallized into a rare addition compound.