Search results for "Nitro"

Friessche Verschiebung vonortho- undpara-Methoxyphenylacetaten. Die Bildung von Ketoestern

1980

During theFries rearrangement ofo- andp-methoxy phenyl acetates with AlCl3 in nitromethane at 20°C substitution occurs mainly in thep-position of the phenolic residue to yieldp-acylphenols. Larger quantities ofo-acylphenols are obtained only, if thisp-position is already substituted. Witho-methoxy phenyl acetates the substitution of the acid residue to yield ketoesters is observed as a side reaction. Those ketoesters are obtained as main products if TiCl4 is taken as a catalyst.

Taurine and the Lung

2003

Taurine (TAU) is the most abundant free amino acid in many tissues and in particular in proinflammatory cells like polymorphonuclear leukocytes and tissues exposed to elevated levels of oxidants1. Furthermore, orally administered TAU has been reported to reduce lung oxidant damage from exposure to ozone, nitrogen dioxide, paraquat, amiodarone and bleomycin in animal models2–5.

An efficient entry to optically active anti- and syn-beta-amino-alpha-trifluoromethyl alcohols.

2008

The reaction of chiral 5,6-dihydro-2H-1,4-oxazin-2-ones with TMSCF3 in the presence of a suitable activator leads to trifluoromethyl lactols, which can be selectively reduced to anti-beta-amino-alpha-trifluoromethyl alcohols. The corresponding syn diastereoisomers are obtained when the starting imines are reduced and the nitrogen atom is conveniently protected. In addition, a novel rearrangement of the CF3 group in the lactol intermediates has been observed. This represents a formal CF3 addition to the imine function in the starting substrates.

Role of Nitric Oxide for Modulation of Cancer Therapy Resistance

2010

Reactive nitrogen species (RNS) act as central second messengers in a balanced cellular network. While the complexity of nitric oxide (NO) signaling is far from being understood, and many controversial data can be found in the literature, there is evidence for NO as a major player of modulation of resistance to anticancer drugs and radiotherapy. Hypoxia in cancer tissues causes therapy resistance, and the hypoxia-inducing factor-1 (HIF-1) plays a predominant role in hypoxia-induced resistance. NO and NO-donating compounds sensitize tumor cells by inhibiting HIF-1 mediated transcription in hypoxic cells. Among a plethora of other genes, HIF-1-induced the transcription of the multidrug resist…

Polycondensed nitrogen heterocycles. Part24. Pyrrolo[3,4-c]isoquinolinone by thermal rearrangement of a pyrrolylbenzotriazinone

1992

Rearrangement under acidic conditions of the pyrrolylbenzotriazinone 7 afforded the pyrrolylbenzamides 10 and 11. By thermal rearrangement instead, the first fully aromatic derivative of the pyrrolo[3,4-c]isoquinoline ring system 9 was obtained.

Nitrous oxide emission hotspots from organic soils in Europe

2014

Abstract. Organic soils are a main source of direct nitrous oxide (N2O) emissions, an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta study with a total amount of 659 annual N2O measurements whic…

Photochemical Nitration by Tetranitromethane. Part XL. Regiochemistry of Trinitromethyl Attachment in the Photolysis of Benzofuran with Tetranitromet…

1997

Polycondensed nitrogen heterocycles. XXII. A new synthesis of 5,6-dihydro-7H-pyrazolo[1,5-d][1,4]benzodiazepin-6-ones

1982

A new synthesis of 2-methyl-9-R'-10-R-5,6-dihydro-7H-pyrazolo[1,5-d][1,4]benzodiazepin-6-ones (4a-c) is deserved. Reaction of ethyl hydrazinoacetate hydrochloride with 1,3-diketones 1a-c gave both 3-methyl-5-(4R'-5-R-2-nitrophenyl)pyrazol-1-yl-acetate acids (2a-c) and the corresponding ethyl esters 3a-c. Reduction with the appropiate reducing agent of compounds 2a-c and 3a-c directly gave the title compounds. Compound 4a showed insecticidal properties against the house fly.

ChemInform Abstract: Polycondensed Nitrogen Heterocycles. Part 23. Pyrrolo(3,2-c)cinnolines by a Japp-Klingemann-Type Reaction.

1990

Pyrrolo[3,2-c]cinnoline derivatives were obtained by an unusual Japp-Klingemann reaction involving an intramolecular azadehalogenation on the pyrrole nucleus. Such an azadehalogenation represents the first example of Japp-Klingemann reaction in which the extrusion of positive chlorine ion is verified.

Enantioselective LaIII-pyBOX-Catalyzed Nitro-Michael Addition to (E)-2-Azachalcones

2013

A [La(OTf)3] complex with a new pyBOX ligand bearing a bulky 1-naphthylmethyl substituent at the 4′-position of the oxazoline ring catalyzes the conjugate addition of nitroalkanes to a broad range of (E)-2-azachalcones, providing the expected nitro-Michael products with good yields and enantiomeric excesses up to 87 %. The optical purity of the products can be increased by a single crystallization. A plausible stereochemical model to account for the observed stereochemistry has been proposed.