Cyclic organophosphorus compounds. Part XI. Stereoisomeric aralkyl phosphonates of the 1,3,2-dioxaphosphorinan series

New, configurationally isomeric phosphonates of the 5,5-disubstituted 2-oxo-1,3,2-dioxaphosphorinan series have been prepared. Variable-temperature studies and ABX analyses of the 1H n.m.r. spectra suggest that they are conformationally mobile systems.