نتایج جستجو برای: direct synthesis

تعداد نتایج: 819100  

Journal: :The Journal of organic chemistry 2002
George A Kraus Junwon Kim

Peri-metalation of 4-(dimethylamino)-1-tert-butyldimethylsilyloxynaphthalene (5) followed by reaction with an electrophile and Jones' oxidation affords 5-substituted naphthoquinones.

1999
Matthew L. Welborn

|This work presents results that show how direct digital synthesis (DDS) techniques can be extended to produce frequency modulated (FM) waveforms as well as many types of digitally modulated waveforms, such as PSK or QAM. We show how digitally modulated wave-forms can be eeciently synthesized from tables of pre-computed samples. This work also reports on the implementation of these algorithms i...

2018
Michael S Seifner Masiar Sistani Fabrizio Porrati Giorgia Di Prima Patrik Pertl Michael Huth Alois Lugstein Sven Barth

A low-temperature chemical vapor growth of Ge nanowires using Ga as seed material is demonstrated. The structural and chemical analysis reveals the homogeneous incorporation of ∼3.5 at. % Ga in the Ge nanowires. The Ga-containing Ge nanowires behave like metallic conductors with a resistivity of about ∼300 μΩcm due to Ga hyperdoping with electronic contributions of one-third of the incorporated...

Journal: :The Journal of organic chemistry 2003
George A Kraus Ikyon Kim

The reaction of a chromene with BH(3) followed by treatment with benzoquinone and air is the key step in a direct entry to O-methyl claussequinone.

Journal: :Organic & biomolecular chemistry 2015
Vijay M Dhurandhare Girija Prasad Mishra Sarah Lam Cheng-Chung Wang

A direct installation of a methyl phosphoramidate group by using methyl benzylphosphoramidochloridate into carbohydrates and amino acid is described. This one-step synthesis is efficient for both primary and secondary alcohols and exhibited excellent regioselectivity and functional group compatibility. Formation of a single diastereomer is observed in certain cases. The N-benzyl protecting grou...

2008
Svetlana A. Krasnova Victor A. Utkin Anton V. Utkin

Manipulator endpoint location autonomous control procedures are suggested. A method of uplimited control hierarchy has been designed, which allows to provide a desired tracking precision under conditions of uncertainty of the control object operator and the effect of external unmeasured disturbances. Sliding mode state observers synthesis procedures have been designed, which allow, in a theoret...

Journal: :Nanoscale 2015
M J Powell P Marchand C J Denis J C Bear J A Darr I P Parkin

Monoclinic VO2 nanoparticles are of interest due to the material's thermochromic properties, however, direct synthesis routes to VO2 nanoparticles are often inaccessible due to the high synthesis temperatures or long reaction times required. Herein, we present a two-step synthesis route for the preparation of monoclinic VO2 nanoparticles using Continuous Hydrothermal Flow Synthesis (CHFS) follo...

Journal: :Organic & biomolecular chemistry 2009
Jonathan Clayden Stephen J M Rowbottom Warren J Ebenezer Michael G Hutchings

Successive treatment of cyanuric chloride with two aromatic diamines, at least one of them sulfonated, yields water-soluble sulfonated azacalix[4]arenes which may be isolated by crystallisation. Functionalised azacalixarenes may be made by first displacing two chloro substituents from the cyclisation precursor. Attempted formation of an azacalix[6]arene led to a dimeric species for which two st...

Journal: :Journal of natural products 2004
George A Kraus Jingqiang Wei

Hyperolactone C is prepared from furan 4. The key transformation is a tandem Claisen rearrangement/lactonization.

Various antibacterial fluoroquinolone compounds were prepared by the direct amination of 7-halo-6- fluoroquinolone-3-carboxylic acids with a variety of piperazine derivatives and (4aR,7aR)-octahydro-1H-pyrrolo[3,4-b] pyridine using Zirconia Sulfuric Acid (ZrSA) nanoparticle, as a catalyst in the presence of ordinary or magnetized water upon reflux condition. The results showed that ZrSA exh...

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