Syntheses and Biological Activities of Ethyl N-Hydroxy-N-(substituted) phenyloxamates as KARI Inhibitors

Nine ethyl N-hydroxy-N-(substituted) phenyloxamates (2a-2i), based on the structure of the KARI inhibitor IpOHA, were synthesized. Their structures were established on the bases of 1H NMR, IR, ESI-MS and elemental analyses. Among the nine compounds, four show in vitro inhibitory activity on rice KARI, with 2c and 2g[Ki values of (35.2 ±4.9) and (49.4 ± 6.3) μmol/L] having similar activity to the precursor of IpOHA(A, Ki=34.1 ± 6.7 (μmol/L). The results will be helpful to further molecular design of more potent KARI inhibitors.