The invention discloses a preparation method for
trelagliptin and a salt thereof. The preparation method comprises the following steps: a, subjecting a compound 3, Pd(OAc)2, ligand, K3PO4, 3-tertbutyloxycarbonyl-aminopiperidine, and an
organic solvent to a reaction with stirring under the protection of
nitrogen so as to obtain a reaction solution; b, carrying out separation and purification so as to obtain a compound 6; c, subjecting the compound 6,
ethyl acetate and an
ethyl acetate solution of HCl to a reaction with stirring and then carrying out separation and purification so as to obtain a
solid; and d, dissolving the
solid obtained in the step c in water, adjusting a pH value to 8 to 9 and then carrying out separation and purification so as to obtain a compound 4, i.e.,
trelagliptin. The preparation method provided by the invention reduces side reactions and production of
impurity compounds; the method is simple and convenient in separating and purifying
trelagliptin and has the advantages of short production period, high yield, high purity, low cost, etc.; and the yield of trelagliptin in the invention can reach 95% or above, and the preparation method is suitable for industrial production.