22575-27-5Relevant academic research and scientific papers
Coupling of Reformatsky Reagents with Aryl Chlorides Enabled by Ylide-Functionalized Phosphine Ligands
Hu, Zhiyong,Wei, Xiao-Jing,Handelmann, Jens,Seitz, Ann-Katrin,Rodstein, Ilja,Gessner, Viktoria H.,Goo?en, Lukas J.
supporting information, p. 6778 - 6783 (2021/02/01)
The coupling of aryl chlorides with Reformatsky reagents is a desirable strategy for the construction of α-aryl esters but has so far been substantially limited in the substrate scope due to many challenges posed by various possible side reactions. This limitation has now been overcome by the tailoring of ylide-functionalized phosphines to fit the requirements of Negishi couplings. Record-setting activities were achieved in palladium-catalyzed arylations of organozinc reagents with aryl electrophiles using a cyclohexyl-YPhos ligand bearing an ortho-tolyl-substituent in the backbone. This highly electron-rich, bulky ligand enables the use of aryl chlorides in room temperature couplings of Reformatsky reagents. The reaction scope covers diversely functionalized arylacetic and arylpropionic acid derivatives. Aryl bromides and chlorides can be converted selectively over triflate electrophiles, which permits consecutive coupling strategies.
Construction of Cholesterol Oxime Ether Derivatives Containing Isoxazoline/Isoxazole Fragments and Their Agricultural Bioactive Properties/Control Efficiency
Xu, Hui,Zhang, Kong,Lv, Min,Hao, Meng
, p. 8098 - 8109 (2021/08/03)
To explore natural-product-based pesticidal candidates and high value-added application of cholesterol in agriculture, oximinoether derivatives of cholesterol-containing isoxazoline/isoxazole fragments (I-1～I-16 and II-1～II-18) were semiprepared by structural optimization of cholesterol. Their structures were characterized by optical rotation, high-resolution mass spectrometry (HRMS), IR, and 1H NMR spectroscopy. Particularly, the Z configurations of oxime fragments at the C-7 position of target compounds were undoubtedly determined by X-ray crystallography. Against Mythimna separata Walker, compounds 3e, I-8, I-14, and II-3 showed 2.4-2.7-fold growth inhibitory activity of the precursor cholesterol. Against Plutella xylostella Linnaeus, compounds I-6, I-7, and I-9 showed 2.4-2.7-fold oral toxicity of cholesterol. Against Aphis citricola Van der Goot, compounds 2e and II-15 exhibited 4.9 and 5.8-fold aphicidal activity of cholesterol, respectively. Notably, they showed good control effects (3.0-5.0-fold promising control efficiency of 1) against A. citricola in the greenhouse. Structure-activity relationships (SARs) suggested that the C-3 hydroxyl group and the C-7 position of cholesterol are two important modification sites. It will pave the way for future structural optimization and application of cholesterol derivatives as potential pesticidal agents in agriculture.
Natural-product-based pesticides: Semisynthesis, structural elucidation, and evaluation of new cholesterol–matrine conjugates as pesticidal agents
Hao, Meng,Li, Tianze,Lv, Min,Xu, Hui,Xu, Jianwei,Zhang, Shaoyong
, (2021/09/07)
To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new cholesterol–matrine conjugates (I(a–e)–IV(a–e)) were prepared from two lead compounds cholesterol and matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3 and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0 folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads for further structural optimization as the insecticidal and aphicidal agents.
Organic reactions in liquid crystalline solvents. 1. The thermal cis-trans isomerization of a bulky olefin in cholesteric liquid crystalline solvents
Leigh, William J.,Frendo, Debbie T.,Klawunn, Paul J.
, p. 2131 - 2138 (2007/10/02)
The effect of cholesteric liquid crystalline solvents on the energetics of rotational thermal cis-trans isomerization of olefins has been examined.Rate constants have been obtained over a 70-degree temperature range for isomerization of trans-1,2-di-(4-cyanophenyl)-1,2-diphenyl-ethylene in two isotropic solvents and three cholesteric liquid crystals and the Arrhenius parameters determined.The rates of isomerization are found to be consistently slower in the liquid crystalline phases compared to the isotropic solvents.The Arrhenius parameters for isomerization of the olefin in the isotropic solvents (Ea = 34.8 +/- 0.3 kcal/mol; ΔS+ = - 1.5 +/- 0.5 e.u.) compare favourably with reported values for its isomerization in benzene solution.In the cholesteric phases, Ea is consistently 1-1.5 kcal/mol higher and ΔS+ slightly more positive than the corresponding values for the isotropic solvents.The results are tentatively rationalized in terms of disruption of liquid crystalline orders as the olefin twists from its pseudo-planar, ground state geometry through the globular, twisted transition state.The magnitude of this effect is proposed to depend on both the difference in steric bulk of the ground and transition states and the "tightness" of the solvation shell seen by the isomerizing molecule.It is believed that in the present case the observed effects are somewhat truncated as a result of rather poor solvation of the bulky olefin in the liquid crystalline phases.
