Linagliptin Dimer Impurity

Chemical Name: 8-((R)-3-aminopiperidin-1-yl)-7-(but-2-yn-1-yl)-1-((4-(2-(((R)-1-(7-(but-2-yn-1-yl)-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl)piperidin-3-yl)amino)ethyl)quinazolin-2-yl)methyl)-3-methyl-3,7-dihydro-1H-purine-2,6-dione