Preparation technique of dabigatran methanesulfonate

The invention discloses a preparation technique of dabigatran methanesulfonate. The technique comprises the following steps: 1) by using a compound I and glycine as raw materials, carrying out condensation and salification to obtain a compound II; 2) by using p-halobenzonitrile (III) as a raw material, synthesizing p-halobenzamidine (IV) under the actions of a catalyst and an aminating agent, and carrying out condensation on the p-halobenzamidine (IV) and n-hexyl chloroacetate to obtain a compound V; and 3) carrying out condensation and salification on the compound V and the compound II to obtain the dabigatran methanesulfonate. The synthesis method has the advantages of mild reaction conditions for each step and high selectivity, and is simple to operate. The dabigatran methanesulfonate has high yield and purity. The technique has the advantages of less discharge of three wastes and environment friendliness, does not need column chromatography purification, and is suitable for industrial production.