Gabapentin enacarbil was prepared and purified from intermediates such as 1-haloalkyl carbamate or carbonate and diacid acetal skeleton. For example, a 1-haloalkyl carbonate or carbamate was prepared by combining a C1 to C10 alcohol or C1 to C10 primary amine, a solvent selected from the group consisting of: acetonitrile, C3 to C7 ketone, C5 to C10 ether, C2 to C7 ester, C5 to C10 hydrocarbon and a combination thereof; a 1-haloalkyl haloformate of the following formula: wherein each X is independently selected from Br, I, or Cl; R1 is alkyl or H; and a C6 to C21 tertiary amine.