Linagliptin Impurity -1

8-Bromo-7-(2-butyn-1-yl)-3,7-dihydro-3-methyl-1-[(4-methyl-2-quinazolinyl)methyl]-1H-purine-2,6-dione; 1-[(4-Methylquinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-bromoxanthine; 8-bromo-7-(but-2-yn-1-yl)-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-3,7-dihydro-1H-purine-2,6-dione; [(4-Methylquinazolin-2-yl)methyl]-3-methyl-7- (2-butyn-1-yl)-8-bromoxanthine ;