Synthesis, X‐Ray Structures and Chemistry of Enantiomerically Pure 10,11‐Dihydro‐5‐phenyl‐5H‐dibenzo[b,f]phosphepine 5‐Oxides.

Several phosphepine oxides were synthesised in optically pure form. Sharpless asymmetric dihydroxylation was used to introduce the chiral centres in all cases. Ring closure was achieved using either PhPCl2 or PrPCl2 together with a double nucleophile generated by either a double ortho-lithiation or double bromine–lithium exchange. The X-ray crystal structures of three phosphepine oxides illustrate their different conformations. The NMR spectra of several phosphepine oxides are described as is the chemistry which is shown to differ from that of acyclic phosphine oxides.