Abstract The secondary phosphonate ester exo-2-(dimethoxyphosphoryl) bicyclo [2.2. 1] heptane 1 was prepared by literature methods on a mole scale. This synthetic method was extended to include the stereoselective preparation of the exo-diethyl phosphonate analog 3 in 71% yield. Derivatization of these exo-phos-phonates 1 and 3 required vigorous conditions, but proceeded in moderate to high yields. The configuration about carbon-2 ...