br Chemistry The synthetic route of A

Chemistry The synthetic route of A, B, and C is depicted in Scheme 1. Substituted-amidine and 2-(ethoxymethylene)malononitrile as starting material was used to prepare 4-amino-2-substitutedpyrimidine-5-carbaldehyde 2 according to the literature method.2 is the key intermediate for the preparation of title compounds A, B, and C. The title compounds could be synthesized by a five-step sequence starting from starting material. Various substituted benzoic SU 4312 synthesis reacted with ethanol in the presence of concentrated sulfuric acid to produce substituted ethyl benzoate 3, which reacted with hydrazine hydrate in ethanol to produce corresponding hydrazide 4. Finally, the new N-acylhydrazone pyrimidine derivatives A, B, and C were prepared in good yields by condensing compound 2 with a variety of substituted benzoyl hydrazine in ethanol at reflux. All synthesized compounds were characterized by 1H NMR, 13C NMR, mass spectrometry and elementary analysis.
Results and discussion
Conclusion In the current study, a series of novel ‘open-chain’ classes of E. coli PDHc E1 inhibitors, N-acylhydrazone pyrimidine derivatives A, B, and C were designed and synthesized. As novel ThDP analogs, all A displayed moderate to powerful inhibitory activity with IC50 values in the range of 0.15–23.55µM against E. coli PHDc E1. The inhibitory potency of compounds against E. coli PDHc E1 could be greatly enhanced when the linkage (between pyrimidine and benzene ring moiety) of lead compound I was replaced with N-acylhydrazone moiety. Moreover the substituted on the pyrimidine ring in parent structure also played a very important role in inhibitory potency against E. coli PDHc E1. The Me group as substituent group on the pyrimidine ring was much beneficial to inhibitory activity, compared with H or NH2 group. These results recommend that the structure skeleton of A is better than both B, C and lead structure I for finding more powerful PDHc E1 inhibitor. Among these title compounds, compounds A13, A14, A15, and C2 were found to be very effective inhibitors of E. coli PDHc E1, with IC50 values ranging from 0.15 to 0.60µM. They also exhibited good enzyme-selective inhibition between microorganisms and mammals. Compound A14, with inhibition rates of 99.37% at 500μgmL−1 against Xanthimonas oryzae pv. Oryzae, was the most powerful inhibitor of E. coli PDHc E1 among title compounds. Binding mode analysis revealed that A14 displays a π-π stacking with the side chain ring of Phe602, and four key hydrogen bonding interaction is made by the nitrogen and oxygen atom with the side chain of Glu571, Met194, Glu522, Leu264.The two NO2 groups not only could form three strong hydrogen bonds with Lys392, Asn260, and His106, but also could establish a coordinate-bond with the Mg2+. The above hydrogen bonding interaction in turn seems to be important for enhancing its inhibitory potency. The site-directed mutagenesis and enzymatic assays further verified that the interaction between A14 with Glu571, Met194, Glu522, Leu264 and Phe602 had a significant contribution for its inhibitory activity against E. coli PDHc E1. Therefore, the skeleton of N-acylhydrazone pyrimidine derivatives A could be as the novel lead structure for further optimization.