Design, Synthesis and Bioactivities of Novel Dichloro-Allyloxy-Phenol-Containing Pyrazole Oxime Derivatives
In this study, in order to find novel biologically active pyrazole oxime compounds, a number of dichloro-allyloxy-phenol-containing pyrazole oximes were designed and synthesized according to the method of active group combination. All of the target compounds were confirmed by 1H-NMR, 13C-NMR and elemental analysis. In addition, bioassays showed that all of the newly synthesized compounds had no acaricidal activity against Tetranychus cinnabarinus and low insecticidal activity against Aphis craccivora at tested concentrations. However, most of them displayed excellent insecticidal activity against Oriental armyworm at a concentration of 500 μg/mL, and some designed compounds still exhibited potent insecticidal activity against Oriental armyworm even at the dose of 20 μg/mL, especially compounds 7f, 7n and 7p had 100%, 90% and 90% inhibition rates, respectively, which were comparable to that of the control pyridalyl.
Synthesis and insecticidal activities of novel pyrazole oxime ether derivatives with different substituted pyridyl rings.
BACKGROUND
Pyrazole oxime ether derivatives with different substituted pyridyl rings represent new types of compounds that possess good insecticidal and acarcidal activity against Aphis laburni Kaltenbach and Tetranychus cinnabarinus.


RESULTS
In total, 82 novel pyrazole oxime ether derivatives were synthesized and identified by (1) H NMR, elemental analysis or high-resolution mass spectrometry, and their insecticidal and acarcidal activities were tested against A. laburni Kaltenbach and T. cinnabarinus. Bioassays showed that at a 200 mg L(-1) dosage, one-third of the compounds displayed high insecticidal activity against A. laburni Kaltenbach (> 90%), whereas most of of the compound II series exhibited excellent acarcidal activity against T. cinnabarinus (> 92%). Most compound II series exhibited good activity in both insecticidal and acarcidal tests. In addition, at a low concentration of 10 mg L(-1) , the insecticidal activity of compounds IB9 and IE4 exceeded 90%, and the acarcidal activity of compounds IIB1 and IIB2 was ≥ 95%.


CONCLUSION
Structure-activity relationships were also examined. Results suggested that the tert-butoxycarbonyl group, as well as the position between tert-butoxycarbonyl and the atom N of the pyridyl ring, were essential to obtaining the acarcidal activity of the title compounds.
Kinetics and mechanism of Vilsmeier-Haack synthesis of 3-formyl chromones derived from o-hydroxy aryl alkyl ketones: A structure reactivity study
Abstract Kinetics of Vilsmeier-Haack reaction with o -hydroxy acetophenones (OHAP) have been investigated in different solvent systems comprising either a single component viz., dichloromethane (DCM), dichloroethane (DCE), acetonitrile (ACN), benzene or binary solvent mixtures of benzene and acetonitrile. The study revealed a total second order kinetics with a first order dependence on each of the [reactant] namely, [VH adduct] and [OHAP]. Increase in the dielectric constant (D) of the medium altered the rate of the reaction non linearly. The data did not fit into either Amis or Kirkwood's theories. These results were interpreted in terms of solvent-solute and solvent-cosolvent interactions. Structure-reactivity correlations have been explained by Hammett's equation.