(2E)-3-(3-Pyridinyl)-2-propenoic Acid-d4 is labelled (2E)-3-(3-Pyridinyl)-2-propenoic Acid (P991835) which is used to synthesize aminomethyl benzimidazoles as inhibitors of gelatinase B. It can also be used to prepare aminopyridines as antibacterial enoyl ACP reductase inhibitors.