Indium as a radical initiator in aqueous media: intermolecular alkyl radical addition to CN and CC bond

The carbon-carbon bond-forming method in aqueous media was investigated by using indium as a single-electron transfer radical initiator. The indium-mediated intermolecular alkyl radical addition to imine derivatives and electron-deficient CC bond proceeded effectively.     

相转移催化下二醇类及肟类的选择性间接电氧化

在对Cr(VI)/Cr(III)体系在相转移催化下对醇类的选择性间接电氧化进行了探讨,发现共醇类能被高产率、选择性地氧化为相应的羰基化合物,而非苄醇类则无此效果的基础上,本文是在此基础上,对分子内含有苄醇羟基和另一个非苄醇羟基的二醇类及肟类化合物进行了选择性电氧化的探讨,结果发现,在本实验条件下,共醇羟基能被选择性地氧化为相应的羰基,而分子内共存的非苄醇羟基几乎不受影响;各种肟类化合物也能有选择地氧化裂解为相应的羰基化合物,而不被深度氧化。     

Modular Oxime Formation by a trans-AT Polyketide Synthase

Modular trans-acyltransferase polyketide synthases (trans-AT PKSs) are enzymatic assembly lines that biosynthesize complex polyketide natural products. Relative to their better studied cis-AT counterparts, the trans-AT PKSs introduce remarkable chemical diversity into their polyketide products. A notable example is the lobatamide A PKS, which incorporates a methylated oxime. Here we demonstrate biochemically that this functionality is installed on-line by an unusual oxygenase-containing bimodule. Furthermore, analysis of the oxygenase crystal structure coupled with site-directed mutagenesis allows us to propose a model for catalysis, as well as identifying key protein-protein interactions that support this chemistry. Overall, our work adds oxime-forming machinery to the biomolecular toolbox available for trans-AT PKS engineering, opening the way to introducing such masked aldehyde functionalities into diverse polyketides.     

In vitro antifungal activity of flavonoid diglycosides of Mentha piperita and their oxime derivatives against two cereals fungi

Flavonoids due to their various interesting biological properties such as antifungal activity were investigated in Mentha piperita leaves. The butanolic fraction obtained from the hydro-alcoholic crude extract of M. piperita is rich in flavonoids; it reduced in vitro the mycelium growth of Phoma sorghina and Fusarium moniliforme around 72% and 55%, respectively, when used at a concentration of 5 mg/ml. In addition, the chemical conversion of the flavonoids in the butanolic fraction into their oxime derivatives increased the antifungal activity since the percentage of inhibition increased to 84% and 65% against P. sorghina and F. moniliforme, respectively, at 5 mg/ml. Butanolic fraction and oxime inhibition effects on spore germination of the two fungi were also observed. These results suggest that, M. piperita flavonoids could be used as botanical fungicides to protect cereals against infection from P. sorghina and F. moniliforme.     

An efficient deprotection of oximes to carbonyls catalyzed by silica sulfuric acid in water under ultrasound irradiation

Deprotection of oximes to the corresponding carbonyl compounds in silica sulfuric acid/surfactant/paraformaldehyde system can be carried out in excellent yields at 50 °C in water under ultrasound irradiation.     

Microwave-promoted one-pot conversion of alcohols to oximes using 1-methylimidazolium nitrate, [Hmim][NO3], as a green promoter and medium

A wide variety of oximes were prepared from different types of alcohols with hydroxylamine hydrochloride using 1-methylimidaziloum nitrate, [Hmim][NO₃], ionic liquid as a reaction medium and promoter under microwave irradiation. This protocol provides a one-pot oxime synthesis with high yields that is facile, eco-friendly and the ionic liquid can be recovered and reused.     

硫酸介质中控制碳钢腐蚀的烷基取代Piperidin-4-one Oximes的立体效应

Three synthesized piperidin-4-one oximes,3-ethyl-2,6-diphenyl-piperidin-4-one oxime(A),1-methyl-3-isopropyl-2,6-diphenyl-piperidin-4-one oxime(B),and 3-isopropyl-2,6-diphenyl-piperidin-4-one oxime(C),were tested at different concentrations to determine their ability to inhibit corrosion of mild steel in 1 mol.L-1 H2SO4 and measured by a mass loss method(at various temperatures),polarization and impedance measurements,X-ray diffraction(XRD),scanning electron microscopy(SEM) with energy-dispersive X-ray spectroscopy(EDS),and a quantum chemical method.The synergistic influence of compounds A,B and C with iodides has also been evaluated.All three compounds show good inhibition efficiency in the following order:A>B>C.Compounds A,B and C were found to physically adsorb on the surface of mild steel while obeying the Temkin isotherm.Polarization measurements indicated that these compounds behave as a mixed mode inhibitor.XRD and SEM with EDS studies revealed the formation of a protective barrier on the mild steel surface by these oximes.The electron donating ability of the studied molecules was tested using semi empirical methods.The studies revealed that the oxime nitrogen,the piperidine moiety,and the phenyl ring assist largely in corrosion control.The studies also showed that the steric crowding by the alkyl group in the piperidine ring affects the inhibitor efficiency.Further,it is interesting to note that all of the studied compounds exhibit synergism with iodide ions.     

Synthesis of Novel 1-Alkyl-2-chloro（alkoxy）-1H-indole 3-Carbaldehyde Oximes and Oxime-ethers（esters） Derivatives

A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes(5a―5d) and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes(6a―6d) from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with N-alkylation and oximation as the key steps.An improved one-pot method for the synthesis of 1-alkyl-2-alkoxy-1H-indole-3-carbaldehyde oximes(7a―7h) from 1-alkyl-2-chloro-1H-indole-3-carbaldehydes(3a―3d) was described.The Williamson reactions and esterification reactions were performed and the oxime-...     

A chemoselective ligation for the synthesis of amino acid derivatives of virginiamycin M1

An efficient chemoselective ligation approach using an oxime bond was developed for the synthesis of amino acid derivatives of virginiamycin M₁, a highly sensitive streptogramin antibiotic.