Quantum-chemical research of the mechanism of synthesis of 1-[2-(о-acetylmethyl)- 3-о-acetyl-2-ethyl]-methyl dichlorine phosphate for the first time is executed by classical method MNDO. This compound is received by reaction of bimolecular nucleophilic substitution SN2, proceeding between acetyl chloride and 5-acetyloxymethyl-2-chlorine-5-ethyl-1,2,3-dioxaphosphorynan. Reaction is endothermic and has barrier character. The size of a power barrier makes 176 kDg/mol.