(R)-tert-Butyl (1-(1-(2-((2-acetylphenyl)amino)-2-oxoethyl)-7-(but-2-yn-1-yl)-3-methyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl)piperidin-3-yl)carbamate (Linagliptin Impurity)

(R)-tert-Butyl (1-(1-(2-((2-acetylphenyl)amino)-2-oxoethyl)-7-(but-2-yn-1-yl)-3-methyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl)piperidin-3-yl)carbamate (Linagliptin Impurity)