In this paper, a synthetic route of oral antidiabetic drug-linagliptin based on the removal of protective group was studied. The key intermediate was obtained from methyl urea by 6 steps of cyclization, nitrosation, reduction, cyclization, Bromination and substitution. The intermediate 2-chloromethyl-4-methylouwarin was synthesized from o-aminoacetophenone by condensation, cyclization and reduction. Based on these two intermediates, linagliptin was prepared by a series of substitution reactions. The experimental results show that the synthesis ...
