Linagliptin Impurity 13 Catalogue L562363 CAS 1446263-39-3 M.W 553.45 M.F C25H29BrN8O2 Specifications FAQs (R,E)-8-(3-Aminopiperidin-1-yl)-7-(3-bromobut-2-enyl)-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-1H-purine-2,6(3H,7H)-dione