Methyl substitution at the double bond of N-alkenyl anilides influences both the preferred conformation and the susceptibility to acidic hydrolysis. The R1-substituted amide favors the trans conformation, whereas amides substituted at R2 or R3 favor the cis conformation. Substitution at the R1 and R3 positions increases the ratio of the trans conformer. DFT study indicated that these conformational preferences can be explained in terms of substituent-induced torsion twisting of the N-alkenyl moiety relative to the amide plane. R1 substitution enhances the susceptibility to acidic hydrolysis, whereas R2 or R3 substitution increases the stability. The effect of the double bond on the conformational effect was showcased by contrasting the preferred conformation of R1-substituted anilide (trans) and hydrogenated N-isopropyl amide (cis).