Synthesis, Characterization And Bioactivity Of Heterocompounds Containing Pyridine Moieties

N-atom heterocyclic compounds have drawn much attention in the research and development of medical and agricultural fields due to they always show high biological activities, good environmental compatibilities and novel interacting-target properties. According to the principle of molecule designing and combination of active groups, sixty-seven novel heterocyclic compounds bearing pyridine moieties were synthesized from a versatile precursor 3,5-di-functional groups pyridine, derived from the oxidation Hantzsch pyridine. All of them were characterized by 1H NMR, IR, MS spectroscopies and elemental analysis. In addition, the representative compoundsâ… A-d,â…¡A-b,â…¡B-b and V-i were further confirmed by X-ray diffraction crystallographic analysis. A feasible route for formation of amide bond under mild reaction conditions was developed. Meanwhile, the bioactivities of the typical products were also investigated, some of them showed good activity to adjust the growth of Mythimna separata.Ten novel 3,5-bis(pyrazol-3-yl)pyridine derivatives (IA and IB) were designed and synthesized from 3,5-diacetyl-pyridines via addition-elimination, cyclization and N-acylation reactions. The structure of compound IA-d was further confirmed by XRD analysis. The mechanism of acylation was discussed.Sixteen novel 3,5-bis(pyrazol-3-yl)pyridine derivatives (â…¡A andâ…¡B) were prepared from readily available Hantzsch pyridine via oxidation, condensation and cyclization reactions. The diastereomers (â…¡A,â…¡B) could be separated by column chromatography. The structures of enantiomerâ…¡A and mesomerâ…¡B were further confirmed by XRD analysis, respectively. Selected seven compounds showed lower herbicidal activity, insecticidal activity and antifungi activity.Fifteen novel 3,5-bis and eight 3-mono amide bond pyridine derivatives (â…¢A andâ…¢B) were selectively synthesized from 3,5-diethoxylcarbonyl-pyridines via hydrazinolysis, cyclization and aminolysis reactions, in which the pyrazole groups served as excellent leaving groups. The mechanism for the formation of amide bond in the presence of a catalytic amount of acid was presented. Thus, a feasible route for formation of amide bond under mild reaction conditions was developed and it has not been reported yet. Selected eight products exhibited good activity to inhibit the growth of 2 instar larvae of Mythimna separata and weak insecticidal activity against Aphis craccivora Koch.A series of 3,5-bis or 3-mono-(1,3,4-oxadiazol-2-yl) pyridines (â…£A andâ…£B) was obtained by condensation of 3,5-bisacylhydrazide-pyridine and 3-acylhydrazide- pyridine with aryldehydes, followed by intra-molecular cyclization reactions. The mechanism of intra-molecular cyclization in the presence of N.B.S. as halogenation reagent was also discussed. Bioactivity test showed that ten target compounds exhibited preferable inhibit activity to the growth of 2 instar larvae of Mythimna separata. Meanwhile, selected seven products showed a bit antifungi activity against Colletotrichum orbiculare and Sphaerotheca fuligine, but exhibited weak herbicidal activity. The results of primary structure-activity relationship showed properly increasing flexibility of compounds benefited to bioactivity.Nine novel 5-[(1,2,4)-triazol[3,4-b][1,3,4]-thiadiazol-3-yl]-nicotinic acid ethyl ester derivatives were designed and synthesized from 3-acylhydrazide-pyridine via addition, cyclization reactions, and so on. The structure of compoundâ…¤-i was further confirmed by XRD analysis. Selected seven compounds were found to inhibit to the growth of 2 instar larvae of Mythimna separata.