The Phosphorylation of 2-Methyl-Δ2-Oxazoline

In common with other acylating agents, diisopropyl phosphorochloridate reacts with 2-methyl-Δ2-oxazoline in aqueous and ethereal media to yield N-phosphoryl derivatives. In both media, phosphorylation is followed by ring opening between positions 1 and 5, as shown by the isolation of diisopropyl N-acetyl-N-2-chloroethylphosphoramidate and diisopropyl N-acetyl-N-2-hydroxyethylphosphoramidate. The latter compound undergoes further rearrangement, being slowly converted to diisopropyl N-2-acetoxyethylphosphoramidate in aqueous bicarbonate solution.Nuclear magnetic resonance studies of 2-methyl-Δ2-oxazoline in aqueous bicarbonate solution (pH 8.5) reveal that it is all transformed to N-acetylethanolamine within 23 hours. This short lifetime allows speculation regarding the origin of 2-acetamidoethyl diisopropyl phosphate isolated from the reaction of the base with diisopropyl phosphorofluoridate.