Biological activity of two new pyrrole derivatives against stored-product species: influence of temperature and relative humidity.

Members of the pyrrole group are likely to have interesting properties that merit additional investigation as insecticides at the post-harvest stages of agricultural commodities. In the present work, the insecticidal effect of two new pyrrole derivatives, ethyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3i) and isopropyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3k) were studied as stored-wheat protectants against two major stored-product insect species, the confused flour beetle, Tribolium confusum Jaquelin du Val adults and larvae and the Mediterranean flour moth, Ephestia kuehniella Zeller larvae at different doses (0.1, 1 and 10 ppm), exposure intervals (7, 14 and 21 days), temperatures (20, 25 and 30°C) and relative humidity (55 and 75%) levels. For T. confusum adults, in the case of the pyrrole derivative 3i, mortality was low and it did not exceed 32.2% in wheat treated with 10 ppm 3i at 30°C and 55% relative humidity. Progeny production was very low (<1 individual/vial) in all combinations of 55% relative humidity, including control. In the case of the pyrrole derivative 3k, mortality reached 67.8% at 30°C and 55% relative humidity in wheat treated with 10 ppm after 21 days of exposure. Progeny production was low in all tested combinations (≤0.7 individuals/vial) of 55% relative humidity, including control. For T. confusum larvae, in the case of the pyrrole derivative 3i, at the highest dose, mortality was 82.2% at 25°C and 55% relative humidity whereas in the case of 3k it reached 77.8% at the same combination. In contrast, mortality at 75% relative humidity remained very low and did not exceed 13.3%. For E. kuehniella larvae, the highest mortalities, 44.4 and 63.3%, were observed in 10 ppm at 25°C and 55% relative humidity for both pyrrole derivatives. The compounds tested here have a certain insecticidal effect, but this effect is moderated by the exposure, the target species, the temperature and the relative humidity.

Mono- and binuclear copper(I) complexes of thionucleotide analogues and their catalytic activity on the synthesis of dihydrofurans.

The reaction of copper(I) halides with 2-thiouracil (TUC), 6-methyl-2-thiouacil (MTUC), and 4-methyl-2-mercaptopyrimidine (MPMTH) in the presence of triphenylphosphine (tpp) in a 1:1:2 molar ratio results in a mixed-ligand copper(I) complex with the formulas [Cu2(tpp)4(TUC)Cl] (1), [Cu2(tpp)4(MTUC)Cl] (2), [Cu(tpp)2(MPMTH)Cl]·(1)/2CH3OH (3), [Cu(tpp)2(MTUC)Br] (4), and [Cu(tpp)2(MTUC)I]·(1)/2CH3CN (5). The complexes have been characterized by FT-IR, (1)H NMR, and UV-vis spectroscopic techniques and single-crystal X-ray crystallography. Complexes 1 and 2 are binuclear copper(I) complexes. Two phosphorus atoms from tpp ligands are coordinated to the copper(I) ions, forming two units that are linked to each other by a deprotonated TUC or MTUC chelating ligand through a sulfur bridge. A linear Cu-S-Cu moiety is formed. The tetrahedral geometry around the metal centers is completed by the nitrogen-donor atom from the TUC or MTUC ligand for the one unit, while for the other one, it is completed by the chloride anion. Two phosphorus atoms from two tpp ligands, one sulfur atom from MPMTH or MTUC ligand, and one halide anion (Cl, Br, and I) form a tetrahedron around the copper ion in 3-5 and two polymorphic forms of 4 (4a and 4b). In all of the complexes, either mono- or binuclear intramolecular O-H···X hydrogen bonds enhance the stability of the structures. On the other hand, in almost all cases of mononuclear complexes (with the exception of a symmetry-independent molecule in 4a), intermolecular NH···O hydrogen-bonding interactions lead to dimerization. Complexes 1-5 were studied for their catalytic activity for the intermolecular cycloaddition of iodonium ylides toward dihydrofuran formation by HPLC, (1)H NMR, and LC-HRMS spectroscopic techniques. The results show that the geometry and halogen and ligand types have a strong effect on the catalytic properties of the complexes. The highest yield of dihydrofurans was obtained when "linear" complexes 1 and 2 were used as the catalysts. The activity of the metal complexes on the copper(I)-catalyzed and uncatalyzed intramolecular cycloaddition of iodonium ylide is rationalized through electronic structure calculation methods, and the results are compared with the experimental ones.

Synthesis and structural characterization of new Cu(I) complexes with the antithyroid drug 6-n-propyl-thiouracil. study of the Cu(I)-catalyzed intermolecular cycloaddition of iodonium ylides toward benzo[b]furans with pharmaceutical implementations.

The reaction of copper(I) iodide with 6-n-propylthiouracil (ptu) in the presence or absence of the triphenylphosphine (tpp) or tri(p-tolyl)phosphine (tptp) in a 1:1:2 molar ratio forms the mixed ligand Cu(I) complex with formula [CuI(ptu)2](toluene) (1), [CuI(tpp)2(ptu)] (2), and [CuI(tptp)2(ptu)] (3). The complexes have been characterized by FT-IR, (1)H NMR, UV-vis, spectroscopic techniques, and single crystal X-ray crystallography. Two sulfur atoms from two ptu ligands and one iodide form a trigonal geometry around the metal center in 1. Intramolecular interactions through hydrogen bonds lead to a bend ribbon polymeric supramolecular architecture with zigzag conformation. Two phosphorus atoms from two arylphosphines, one sulfur atom, and one iodide anion form a tetrahedron around the copper ion in case of 2 and 3. Intramolecular hydrogen bonding interactions lead to dimerization. Complexes 1-3 and the already known ones with formulas, [(tpSb)2Cu(µ2-I)2Cu(tpSb)2] (4) (tbSb = triphenylstibine), [(tpp)Cu(µ2-I)2Cu(tpp)2] (5), [(tpp)Cu(µ2-Cl)2Cu(tpp)2] (6), [CuCl(tpp)3·(CH3CN)] (7), and [AuCl(tpp)] (8), were used to study their catalytic activity on the intermolecular cycloaddition of iodonium ylides toward benzo[b]furans formation. The results show that both the metal and the ligand type affect the catalytic affinity of the complexes. The highest yield of benzo[b]furan was derived when complexes 2, 3, and 4 were used as catalysts. The mechanism of the Cu(I)-catalyzed and uncatalyzed intramolecular cycloaddition of iodonium ylide has been also thoroughly explored by means of ab initio electronic structure calculation methods, and the results are compared with the experimental ones.