To evaluate feasibility of the formation of amino acid precursors in dense interstellar clouds from methylenimine, HCN, CN radical, water, and OH radical, stationary points for four gas-phase reactions have been computed at the B3LYP/6-311++G(d,p) level of theory. All the reactions are exothermic. For the reaction HN=CH2 + H-C equivalent toN --> H2NCH2-C equivalent toN, three high-energy transition states have been found (energies of ca. 23-33 kcal mol(-1) relative to the reactant level) which do not allow this reaction to occur as a purely gas-phase process. The same conclusion has been done for the further glycine amide formation according to the pathway H2N-CH2-C equivalent toN + H2O --> H2N-CH2 -C(=O)-NH2, where three transitions states have been obtained as well. one of them having relative energy of ca. 52. kcal mol(-1). Reaction HN= CH2 + .C equivalent toN --> H2N-C(. )H-C equivalent toN (> 70 kcal mol(-1) exothermic) exhibits no positive barriers at the theoretical level employed; it is the only one unconditionally feasible in the gas-phase. Despite the fact that for reaction H2N-CH2-C equivalent toN + . OH --> H2N-C(. )H-C(=O)-NH2 (ca. 60 kcal mol(-1) exothermic) four transition states have been found, it might also appear plausible under the interstellar conditions for the following reasons: all the barriers are associated with exclusively proton-transfer processes; only one of them is positive, and three lay below the level of reactants; for the only positive barrier, proton tunneling might facilitate the reaction. Radical products H-NC(. )HCN and H2NC(. )HC(=O)NH2 forming in the latter two cases have a free valence at the carbon atom corresponding to a-C atom in the molecules of biological amino acids. Combining them with a vast variety of open-shell interstellar species is suggested as a possible route to diverse amino acid derivatives in dense molecular clouds.