7-(But-2-yn-1-yl)-8-ethoxy-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-1H-purine-2,6(3H,7H)-dione (Linagliptin Impurity)

7-(But-2-yn-1-yl)-8-ethoxy-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-1H-purine-2,6(3H,7H)-dione (Linagliptin Impurity)