The Reaction of Seven- and Eight- Membered Cyclic Phosphorochloridites with Polyols

Abstract

The syntheses of novel bridged dibenzo[d,f][1,3,2]dioxaphosphepin and dibenzo[d,g][1,3,2]dioxaphosphocin ring systems are described. The ¹H NMR spectral data of the eight-membered bridged dioxaphosphocins suggest the observation of a single conformational isomer. The ¹H NMR spectrum of the dibenzo[d,g][1,3,2]dioxaborocin 5 requires that either a single nonplanar conformation is being observed or that ring inversion is slow on the NMR time scale. A lower limit of δG ^‡ for ring inversion of 5 has been calculated to be 14.4 Kcal/mole. The ¹H NMR of the C-12 methyl substituted dioxaphosphocins 4h-i showed the presence of a cis-trans isomer mixture.