Linagliptin Dimer Impurity 206

8- ((S) -3-aminopiperidin-1-yl) -7- (but-2-yn-1-yl) -1- ((4- (2- (((S) -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

8- ((S) -3-aminopiperidin-1-yl) -7- (but-2-yn-1-yl) -1- ((4- (2- (((S) -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