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. Sharple ss asymmetric dihydroxylation was used to introduce the chiral centres in a ll 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 phos phepine oxides illustrate their different conformations. The NMR spectra of several phosphepine oxides are described as is the chemistry which is show n to differ from that of acyclic phosphine oxides.