Synthesis of Homochiral Dibenzo(b,f)phosphepin 5-Oxides Using a Double ortho-Lithiation Strategy.

Abstract Enantiomerically pure chiral seven membered phosphorus heterocycles — phosphepins — have been prepared by McMurry coupling, Sharpless dihydroxylation, ortho -lithiation and reaction with PhPCl 2 or PrPCl 2 . Studies of the ortho -lithiation and of hydrolysis of phosphepinium salts are included.