Highly enantioselective Diels-Alder reactions of β-fluoromethylacrylates were carried out in the presence of a Lewis acid activated chiral oxazaborolidine catalyst. These reactions yielded ...fluoromethylated cyclohexenes, including trifluoromethyl-, difluoromethyl-, and monofluoromethyl cyclohexenes, as nearly pure enantiomers. The resulting fluoromethyl cyclohexenes were converted into potential synthetic intermediates for bioactive compounds.
An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic ...system proceeded with high regioselectivity to give the ACP products in high yield with high diastereoselectivity (up to 99/1) and enantioselectivity (up to 99% ee).
A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) was developed for determination of anilinopyrimidine fungicide mepanipyrim in vegetables. Two derivatives of mepanipyrim and ...mepanipyrim propanol type metabolite which carried carboxy acid were synthesized and conjugated with keyhole limpet hemocyanin. BALB/c mice were immunized to prepare anti-mepanipyrim monoclonal antibodies (MoAbs) by obtained conjugates. The dc-ELISAs based on the prepared MoAbs, MPP107 and MPP204, showed working ranges between 0.12 and 1.8 ng/mL with mepanipyrim for MPP107, 0.12 and 2.4 ng/mL with mepanipyrim for MPP204, and 0.2 ng/mL and 5.7 ng/mL with the mepanipyrim propanol type for MPP204. The dc-ELISAs showed the sufficient sensitivity to determine the mepanipyrim residues for the MRLs of 1–15 mg/kg among the majority of vegetables and fruits in Japan. Recovery and/or correlation results from HPLC suggested that the dc-ELISAs would be applicable to the residue analysis of mepanipyrim and its propanol type in vegetables.
A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) and an immunosensor based on surface plasmon resonance (SPR-sensor) were developed for fungicide boscalid determination in ...horticultural crops. To produce antiboscalid monoclonal antibodies (MoAb BSC7 and MoAb BSC72) for these assays, a hapten of boscalid was synthesized and conjugated to keyhole limpet hemocyanin for Balb/c mouse immunization. The working range of the dc-ELISA was 0.8–16 ng/mL with MoAb BSC7 and 2.5–120 ng/mL with MoAb BSC72, and that of the SPR-sensor was 17–80 ng/mL with MoAb BSC7. The dc-ELISA and SPR-sensor were compared for their sensitivity in determining boscalid residues at the maximum residue limit of 1–40 mg/kg for horticultural crops in Japan. Recovery of the spiked boscalid was 85–109% by the SPR-sensor and 100–124% by the dc-ELISA. On real tomato samples, the results obtained by both of these immunoassays correlated well with the results obtained by high-performance liquid chromatography.
Nitenpyram, a neonicotinoid insecticide, is highly soluble in water (>5.9 × 10
5
mg/L). Specifically examining its physicochemical properties, we have established a simple and rapid residue ...analytical method for nitenpyram using an enzyme-linked immunosorbent assay (ELISA) which requires no organic solvents. The I
50
value found with this ELISA method using a selective monoclonal antibody toward nitenpyram was 4.8 ng/mL. A hand-shaking method using water was applied for ELISA analysis to extract nitenpyram from fruiting vegetable samples of four kinds. Matrix effects caused by interfering substances coexisting in aqueous sample extracts were reduced by dilution with water. No problems were found in the analytical values obtained using ELISA. From analyses of nitenpyram-incurred fruiting vegetables with the proposed ELISA and the reference HPLC protocols, high mutual correlation was found, which suggests that the measurement accuracy of the proposed ELISA method is comparable to the reference HPLC procedure.
A reusable and highly enantioselective catalyst for the intramolecular cyclopropanation of various diazo ester and Weinreb amide derivatives was developed. The reactions catalyzed by a water-soluble ...Ru(II)-
-Pheox catalyst proceeded smoothly at room temperature, affording the corresponding bicyclic cyclopropane ring-fused lactones and lactams in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). After screening of various catalysts, the Ru(II)-
-Pheox complex having an ammonium group proved to be crucial for the intramolecular cyclopropanation reaction in a water/ether biphasic medium. The water-soluble catalyst could be reused at least six times with little loss in yield and enantioselectivity.
The intramolecular cyclopropanation of various trans‐allylic diazoacetates and alkenyl diazoketones has been achieved with excellent enantioselectivities of up to 98% ee and in quantitative yields by ...using a water‐soluble ruthenium(II)/hydroxymethyl(phenyl)oxazoline catalyst in a water/ether biphasic medium. The catalyst could be reused at least five times.
Photoluminescent divinylbipyrroles were synthesized from 3,3',4,4'-tetraetyl-2,2'-bipyrrole-5,5'-dicarboxaldehyde and activated methylene compounds via aldol condensation. For mechanistic clarity, ...molecular structures of Meldrum's acid- and 1,3-dimethylbarbituric acid-derived divinylbipyrroles were determined by single-crystal X-ray diffraction. Photoluminescent properties of the synthesized divinylbipyrroles in dichloromethane were found to be dependent on the presence of electron withdrawing groups at the vinylic terminal. The divinylbipyrroles derived from malononitrile, Meldrum's acid, and 1,3-dimethylbarbituric acid showed fluorescent peaks at 553, 576, and 602 nm respectively. Computational studies indicated that the alkyl substituents on the bipyrrole 3 and 3' positions increased energy level of the highest occupied molecular orbital (HOMO) compared to the unsubstituted derivatives and provided rationale for the bathochromic shift of the ultraviolet-visible (UV-Vis) spectra compared to the previously reported analogs.
Enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody (MoAb) was developed for the neonicotinoid insecticide clothianidin. A new clothianidin hapten ...(3-5-(3-methyl-2-nitroguanidinomethyl)-1,3-thiazol-2-ylthio propionic acid) was synthesized and conjugated to keyhole limpet hemocyanin, and was used for monoclonal antibody preparation. The resulting MoAb CTN-16A3-13 was characterized by a direct competitive ELISA (dc-ELISA). The 50% of inhibition concentration value with clothianidin was 4.4 ng/mL, and the working range was 1.5-15 ng/mL. The antibody showed high cross-reactivity (64%) to dinotefuran among the structurally related neonicotinoid insecticides. The recovery examinations of clothianidin for cucumber, tomato and apple showed highly agreement with the spiked concentrations; the recovery rate was between 104% and 124% and the coefficient of variation value was between 1.8% and 15%. Although the recovery rate of the dc-ELISA was slightly higher than that of HPLC analysis, the difference was small enough to accept the dc-ELISA as a useful method for residue analysis of clothianidin in garden crops.
Bis(oxazolinyl)phenyl–palladium(II)(Phebox–Pd) complexes were found to be efficient catalysts for Suzuki–Miyaura coupling reactions of aryl boronic acids and their derivatives with aryl halides to ...give the corresponding biaryl products in high yield along with moderate enantioslectivities in the case of axially chiral induction. The catalytic activity was attained more than 900,000 of TON and 45,000 of TOF. The catalyst can be recovered quantitatively and could be reused for Suzuki–Miyaura reactions.
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