Synthesis of Venezuelan Equine Encephalitis Virus (VEEV) Inhibitors using a Two-Step Hippuric Acid Condensation-Lactone Amidation

Abstract

Venezuelan Equine Encephalitis Virus (VEEV) is a mosquito-borne pathogen that commonly infects equines but has transmitted to humans in certain cases. The lack of small molecule antivirals for treatment against VEEV prompted a high throughput screen (HTS), which led to a hit molecule we dubbed DP9. To synthesize DP9 and analogs, we devised a two-step reaction approach comprising hippuric acid condensation and lactone amidation. In step 1, hippuric acid was refluxed with three different aldehydes in acetic anhydride to afford a handful of lactone intermediates. In step 2, two different amidation procedures were developed which allowed for lactone ring opening by amine nucleophiles, modifying the hippuric acid scaffold. Together, the aforementioned two-step sequence provided a diverse series of 8 DP9 analogs, which were fully characterized by 1H and 13C NMR, MS, and LC-UV purity trace. The modulation of aldehyde substituents in step 1 and amine tails in step 2 explores different aromatic electronics, lengths, size, and number of hydrogen-bond donors/acceptors. DP9 analogs inhibitory activity against VEEV was quantified using an alpha-screen assay.