A kind of preparation method of frusemide

The invention belongs to field of medicine and chemical technology, especially a kind of preparation method of frusemide (Furosemide)；Shown in its chemical formula such as formula (1)： The preparation method is as follows：By the tetrahydrofuran-compound representated by formula (2)： Wherein X represents halogen, lower alkyl sulfonyloxy, arylsulfonyloxy or aralkylsulfonyl epoxide, with 2 aminobenzoic acid compounds representated by formula (3) and/or its salt in reaction dissolvent, heat temperature raising, temperature control is 80 150 DEG C, in the presence of acid binding agent and/or catalyst, necleophilic reaction is complete to the formula (3) reaction