Studies on the Synthesis of Novel Four‐Membered Cyclic Oxaphosphetanes via Intramolecular Mitsunobu Reaction of Bishydroxyalkylphosphinic Acids.

Studies on the synthesis of novel four-membered cyclic oxaphosphetanes from bishydroxyphosphinic acids is reported. Investigations showed that the conversion proceeds through an intramolecular Mitsunobu cyclisation of bishydroxyphosphinic acids with a mixture of triphenylphosphine and diisopropylazodicarboxylate (DIAD) in toluene–CH2Cl2 at room temperature. The treatment of two diastereomers of bishydroxymethylphosphinic acids (dl pair and meso) with a mixture of triphenylphosphine and DIAD gives only one stereoisomer of the cyclic oxaphosphetane.