The total stereoselective synthesis of two highly potent phosphodiesterase IVb inhibitors from nitroethane, isovanillin, and ethyl vinyl ether was developed. The compounds obtained are the derivatives of hexahydro-3H-pyrrolo[1, 2-c]imidazol-3-one and tetrahydro-1H-pyrrolo[1,2-c][1,3]oxazol-3-one. The strategy proposed involves silylation of six-membered cyclic nitronates as a key step leading to 5,6-dihydro-4H-1,2-oxazines with the group CH ₂FG (FG = N ₃ or OH) at the C(3) atom.