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Insect pest chitinases are potential target for developing new insect growth regulators. Piperine was found first to inhibit the insect chitinase ( Of Chi-h) from Ostrinia furnacalis (Asian corn borer) in this work, except for previously reported Of ChtI. Novel piperonyl-tethered rhodanine derivatives 7a - j were rationally designed with piperine as lead and synthesized by introducing a unique rhodanine moiety into the piperine scaffold based on the similar binding cavity of Of ChtI and Of Chi-h. Compared to piperine, compounds 7a - j showed approximately 100- to 400-fold or 110- to 210-fold higher inhibitory capacity against two chitinases, respectively. Molecular mechanism studies indicated that π interactions are crucial for improving inhibitory activity against two chitinases due to the introduction of the conjugated rhodanine ring. Moreover, compounds 7a - c could dramatically inhibit the growth and development of O. furnacalis larvae by in vivo activity evaluation. This study provides novel piperonyl-tethered rhodanine derivatives inhibiting dual chitinases as insect growth regulator candidates.

The insect chitinase Of ChtI from the agricultural pest Ostrinia furnacalis (Asian corn borer) is a promising target for green insecticide design. Of ChtI is a critical chitinolytic enzyme for the cuticular chitin degradation at the stage of molting. In this study, piperine, a natural amide compound isolated from black pepper, Piper nigrum L., was discovered for the first time to have inhibitory activity toward Of ChtI. The compound-enzyme interaction was presumed to take place between the piperine benzo[ d ][1,3] dioxole skeleton and subsite -1 of the substrate-binding pocket of Of ChtI. Hence, on the basis of the deduced inhibitory mechanism and crystal structure of the substrate-binding cavity of Of ChtI, compounds 5a - f were designed and synthesized by introducing a butenolide scaffold into the lead compound piperine. The enzymatic activity assay indicated that compounds 5a - f ( K i = 1.03-2.04 μM) exhibited approximately 40-80-fold higher inhibitory activity than the lead compound piperine ( I ) ( K i = 81.45 μM) toward Of ChtI. The inhibitory mechanism of the piperonyl butenolide compounds was elucidated by molecular dynamics, which demonstrated that the introduced butenolide skeleton improved the binding affinity to Of ChtI. Moreover, the in vivo activity assay indicated that these compounds also displayed moderate insecticidal activity toward O. furnacalis . This work introduces the natural product piperine as a starting point for the development of novel insecticides targeting Of ChtI.

A simple chiral primary-tertiary diamine derived from C 2 -symmetric 1,2-diphenylethane-1,2-diamine as the organocatalyst in combination with the trifluoroacetic acid additive for the asymmetric Mannich reaction of cyclic N- sulfonyl trifluoromethylated ketimines and methyl ketones afforded the desired product with high enantioselectivity (73-96% ee). The reactions proceeded well for a variety of different substituted cyclic N -sulfonyl trifluoromethyl ketimines and various alkyl methyl ketones, providing access to diverse enantioenriched benzo-fused cyclic sulfamidate N -heterocycles bearing a trifluoromethylated α-tetrasubstituted carbon stereocenter. This study also investigated the diastereoselective reduction of the carbonyl group and ring cleavage reduction of the sulfamidate group of the corresponding Mannich product.

Geometrical structures of a series of binary azides M(N3)n (M = elements in groups 3 and 13 (n = 3) and in groups 4 and 14 (n = 4)) were investigated at the B3LYP/6-311+G level of theory. Our calculations found that binary group 3 triazides M(N3)3 (M = Sc, Y, La) and binary group 4 tetraazides M(N3)4 (M = Ti, Zr, Hf) turn out to be stable with all frequencies real having a similar linear M-N-NN structural feature, as previously reported for M(N3)4 (M = Ti, Zr, Hf). However, binary azides of group 13 M(N3)3 (M = B, Al, Ga, In, Tl) and group 14 elements M(N3)4 (C, Si, Ge, Sn, Pb) with bent M-N-NN bond angles differ obviously from binary group 3 and 4 azides in geometrical structure. These facts are mainly explained by the difference in electronic density overlap between the central atom and the alpha-N atoms of the azido groups. Two lone-pair electrons on the sp hybridization alpha-N atoms in the binary group 3 and 4 azides donate electron density into two empty d orbitals of the central transition metal atom and a pair of valence bonding electrons, resulting in the alpha-N atoms acting as a tridentate ligand. The sp2 hybridization alpha-N atoms of the binary group 13 and 14 azides only give one valence electron to form one valence bonding electron pair acting virtually as monodentate donors.