نتایج جستجو برای: direct synthesis
تعداد نتایج: 819100 فیلتر نتایج به سال:
Peri-metalation of 4-(dimethylamino)-1-tert-butyldimethylsilyloxynaphthalene (5) followed by reaction with an electrophile and Jones' oxidation affords 5-substituted naphthoquinones.
|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...
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...
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.
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...
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...
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...
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...
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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