Zhongzhen Tian

Synthesis of novel nithiazine analogues containing the 1,4-dihydropyridine structure, and their bioactivity as insecticides

A series of novel nithiazine analogues bearing the 1,4-dihydropyridine structure have been designed and synthesized by reaction of nithiazine, malononitrile or ethyl cyanoacetate, and benzaldehyde. The synthesized compounds were identified by 1H NMR and IR spectroscopy, and elemental analysis. Preliminary bioassays indicated that most of the compounds had moderate insecticidal activity against Aphis craccivora. The relationship between molecular structure and biological activity is discussed.

Synthesis of 1,3-dithiolane-containing nitromethene compounds and their biological activity as insecticides

Abstract1,3-Dithiolane-containing nitromethylene derivatives, as candidates for screening as neonicotinoid insecticides, were synthesized by reaction of compound (4) with 1,2-ethanedithiol. Compounds 7a–g were obtained via Mannich reaction of (E)-1-((1,3-dithiolan-2-yl)methyl)-2-(nitromethylene)imidazolidine (6), primary amines and formaldehyde. The synthesized compounds were identified by 1H NMR, IR spectroscopy and elemental analysis. Preliminary bioassays indicated that most of the compounds had moderate insecticidal activity against Aphis craccivora. The relationship between molecular structure and biological activity is discussed.

1-[(6-Chloro-3-pyrid-yl)meth-yl]-5-eth-oxy-8-nitro-1,2,3,5,6,7-hexa-hydro-imidazo[1,2-a]pyridine.

In the title compound, C15H19ClN4O3, an active agrochemical possessing insecticidal activity, the dihedral angle between the mean planes passing through the pyridine ring and the five-membered ring is 87.3 (2)°. The fused pyridine ring adopts a twisted sofa conformation. The molecular structure features close intramolecular C—H⋯N and C—H⋯O hydrogen bonding.

Design, synthesis and insecticidal activities of dihydropyridine-fused neonicotinoids compounds with trifluoromethyl group

A series of novel neonicotinoids containing a dihydro-pyridine ring and a trifluoromethyl group were designed and synthesized by multicomponent reactions of 6-Cl-PMNI, triethoxymethane and 4,4,4-trifluoro-3-oxobutaneanilides (9) under solvent-free and catalyst-free conditions. The trifluoromethyl group plays an important role as an electron-withdrawing group in enhancing the reaction activity of compound 9. The target compounds were characterized by 1H NMR, IR and elemental analysis. Bioassays indicated that most of the synthesized compounds exhibited moderate insecticidal activities against Aphis craccivora.

Synthesis, biological activity and crystal structure of ethyl 6-amino-8-(4-methoxy phenyl)-9-nitro-2,3,4,8-tetrahydropyrido[2,1b][1,3]thiazine-7-carboxylate

The compound ethyl 6-amino-8-(4-methoxy phenyl)-9-nitro-2,3,4,8-tetrahydropyrido[2,1b][1,3]thiazine-7-carboxylate (C14H22N4O4S2) has been synthesized by multicomponent reactions, and characterized by 1H NMR, IR, and X-ray diffraction. The crystal structure analysis shows that the thiazinane ring displays a half-chair conformation. The benzene ring is almost vertical to the tetrahydro-pyridine ring. Intramolecular H-bonding of N–H···O type exists and completes an S (6) ring. In the crystal, the molecules are connected into a 3D network by a N–H···O and C–H···O intermolecular hydrogen bond. The bioassay indicates that the compound shows moderate insecticidal activity against Aphis craccivora.

1-[(6-Chloro-pyridin-3-yl)meth-yl]-10-nitro-1,2,3,5,6,7,8,9-octa-hydro-5,9-methano-imidazo[1,2-a]azocin-5-ol.

In the title compound, C16H19ClN4O3, the cyclohexane ring displays a chair formation and the tetrahydropyridine ring displays an envelope conformation with the methylene C atom as the flap; the imidazolidine ring also displays an envelope conformation with a methylene C atom as the flap. In the crystal, O—H⋯N hydrogen bonds between hydroxy groups and pyridine rings link inversion-related molecules into dimers. Weak C—H⋯O hydrogen bonds further link the dimers into supramolecular chains running along the c axis.

(E)-1-[(1,3-Dioxan-4-yl)meth­yl]-2-(nitro­methyl­idene)imidazolidine

In the title compound, C9H15N3O4, the 1,3-dioxane ring displays a chair conformation and the five-membered ring is close to planar (r.m.s. deviation = 0.054 Å). An intramolecular N—H⋯O hydrogen bond to one of the nitro-group O atoms generates an S(6) ring. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into C(6) chains propagating in [010] and a C—H⋯O link also occurs.

(E)-1-(2,2-Dimeth­oxy­eth­yl)-2-(nitro­methyl­idene)imidazolidine

In the title compound, C8H15N3O4, the 2-(nitromethylene)imidazolidine fragment is close to being planar (r.m.s. deviation = 0.027 Å), which may be correlated with delocalization of the electrons and the effect of the strongly electron-withdrawing NO2 group. An intramolecular N—H⋯O link generates an S(6) ring. The same H atom also forms a weak intermolecular N—H⋯O hydrogen bond, which results in C(7) chains propagating in [010].

1-[(1,3-Dithio­lan-2-yl)meth­yl]-8-nitro-6-propyl-1,2,3,5,6,7-hexa­hydro­imidazo[1,2-c]pyrimidine

In the title compound, C13H22N4O2S2, the six-membered ring displays a half-chair conformation. The olefin amine unit is close to being coplanar with the imidazolidine ring (r.m.s. deviation = 0.059 Å). The dithiolane ring adopts a twisted conformation. In the crystal, molecules are linked by weak C—H⋯O interactions.

1-(2,2-Dimeth­oxy­eth­yl)-8-nitro-1,2,3,5,6,7-hexa­hydro­imidazo[1,2-a]pyridin-5-ol

In the title compound, C11H19N3O5, the six-membered ring displays a half-chair conformation and the imidazolidine ring is essentially planar (r.m.s. deviation = 0.088 Å). An intermolecular hydrogen bond between the hydroxy O atom and a nitro O atom stabilizes the crystal packing.