(2E)-1,3-Dibromo-2-butene is an intermediate in the synthesis of N-Des-(2-butyn-1-yl)-N-(3-bromo-2-buten-1-yl) Linagliptin (E/Z Mixture) (D282015), an impurity of Linagliptin (L465900); a novel potent and selective dipeptidyl peptidase-4 (DPP-4) inhibitor with potential use in the treatment of type 2 diabetes.