Nitro phenylacetylene

Dinitro a cbloTOStyrene, OjN-CgH -CCltCH.NO no description given, mp 105° was prepd by reaction of m-nitro-phenylacetylene with nitrosyl chloride (NOCl) for several weeks(Ref 7) ... 

In contrast to other furoxans, the cycloreversion of 3,4-dinitrofuroxan to nitro-formonitrile oxide was observed even at room temperature. The nitrile oxide could be trapped in situ with electron-deficient nitriles (Scheme 149) (95MC231). Attempts to obtain cyclo adducts with styrene, phenylacetylene, rran.s-stilbene, and cyclohexene failed. 

It is noteworthy that the only deiodinated product (4-nitro-1,3-dimethylpyrazole) was isolated in a 70% yield (86TH1) by cross-coupling phenylacetylene with 5-iodo-4-nitro-l,3-dimethylpyrazole (Scheme 44). 

These authors observed that in 80% aqueous ethanol, the rates were pseudo first order in bromostyrene, except for the P-NO2-isomer, which did not react even at 190° C. The products of reaction in the cases where X = NH2, CH3CONH, and CH3O were exclusively the corresponding acetophenones and, for X = H, 74% acetophenone and 22% phenylacetylene. Reaction rates were found to increase with solvent polarity as well as addition of silver ion, but they were independent of added triethylamine (except in the very unreactive p-nitro isomers, where in the presence of added amine, a second-order reaction ensued that resulted exclusively in p-nitrophenylacetylene as product). 

Die direkte, reduktive Aminierung einer acetylenischen Gruppe gelingt bei 2-Ethinyl-pyri-dinen durch Erhitzen mit Methylamin-Hydrochlorid und Natrium-cyanoboranat in Ethanol2. So erhalt man z. B. aus 2-Ethinyl-6-methyl-pyridin bei einer Reaktionszeit von 24 h 2-(2-Dimethylammo-ethyl)-6-methyl-pyridin in 76% Ausbeute. Mit Phenylacetylen gelingt die Reaktion nicht aus (4-Nitro-phenyl)-acetylen und Methylamin-Hydrochlorid erhalt man dagegen in glatter Reaktion l-Methylamino-2-(4-nitro-phenyl)-ethan. 

Unlike W and Mo catalysts, Rh catalysts are not suited to oriho-swhstxtutcd phenylacetylenes because Rh catalysts are rather sensitive to the steric effect. Instead, Rh catalysts are suitable to various phenylacetylenes having polar groups (e.g., ether, ester, amine, carbazole, imine, nitrile, azobenzene, nitro groups) at ra-position, resulting in the formation of high MW poly(phenylacetylenes). Many such examples are found in Table 3. 

Arylpropiolic acids lose carbon dioxide when refluxed with water. or a solution of sodium bicarbonate and cupric chloride. Yields of phenylacetylenes containing nuclear halo, alkoxyl, and nitro groups are in the range of 40-67%. Alkylphenylacetylenes, C,H,C=CR, may be made directly from a-alkylcinnamic acid dibromides, C4H5 CHBrCRBrCO,H, by dehydrohalogenation and decarboxylation. ... 

A study of the photohydration of the alkynes 11 and 12 in sulphuric acid has shown that only the normal Markownikov products, in this instance in the keto form 13, are formed. The mechanism, as proposed by Yates and collaborators involves a rate-limiting protonation of the Si state of the alkyne. This leads to the cation 14, solvation of which affords the enol of the final product. Associated with this, and providing spectroscopic substantiation, is the report of the direct observation of the enol of acetophenone during a study of the photohydration of phenylacetylene The introduction of nitro substituents as in 15 leads to abnormal Markownikov addition products. Excitation in these systems results in a reversal of polarity in the excited state, consistent with the... 

Hydrogenization of unsaturated and aromatic nitro canopounds oligomerization of phenylacetylene... 

CHF CFa, from hexafiuoropropene and propene at 250 °C, the formation of addacts between ethyl a>fluoroacrylate and chlorotrifluoro- or tetrailuoro-ethylene, preparation of various 1,1,2-trifluorocyclobutanes as anaesthetics, and the formation of adducts (78 X = Y = F or Cl X = F, Y = O) from diethyl itaconate at 180 °C, where diethyl dtraconate failed to react. 2-Alkoxy-3-phenylcyclobut-2-enoiies are formed when the adducts of styrene and CF tCFCl or CFgiCFj are treated with potassium hydroxide in ethanol or potassium t-butoxide in t-butanol, respectively. The adducts of / -nitro- and p-methoxy-phenylacetylene and chlorotrifluoro-ethylene may be hydrolysed by concentrated sulphuric acid to arylcyclo-butenediones. Tetrafluoroethylene adds photochemically to 3p-acetoxy-pregna-5,16-dien-20-one by [2 + 2] addition to the C—C bond of the enone grouping and by [2 + 4] addition to this function. ... 

To determine the effects of an electron withdrawing or donating moiety on the electrical properties of these compounds, materials with solely an amine, nitro, or acetamide moiety have been synthesized. 2,5-Dibromonitrobenzene was coupled with TMSA at the more reactive bromide, a to the nitro moiety, followed by coupling with phenylacetylene. Deprotection of the terminal alkyne afforded intermediate 77. Coupling of 77 with 3 afforded product 78 (Scheme 3.36). 

Ethynylphenyl)-4-nitro-5-(trimethylsilylethynyl)acetanilide (74). See the general procedure for the Pd/Cu-catalyzed coupling reaction. 2-Bromo-4-nitro-5-(trimethylsilylethynyl)acetanilide (1.20 g, 3.38 mmol) was coupled to phenylacetylene (0.56 mL, 5.07 mmol) as described above using Cul (0.06 g, 0.34 mmol), ((C6H5)3P)2PdCl2 (0.12 g, 0.17 mmol),... 

The synthesis of compound 26 was initiated to study the effect of the nitro group in relation to the chemisorbed pyridine alligator clip. To this end, compound 24 was synthesized in a manor analogous to the synthesis of 23 as shown in Scheme 3.58. Coupling one equivalent of phenylacetylene selectively to 2,5-dibromonitrobenzene to produce 25 then coupling to 21 to afford 26 in good yield completed the synthesis. 

Nitromethyl ketones react with p-toluenesulfonic acid (PTSA) in refluxing toluene to give the corresponding furo-xans in 97% yield [20]. When refluxed several hours in xylene or mesitylene in the presence of dipolarophiles and catalytic PTSA, not only activated nitro compounds but also phenylnitromethane and 1-nitropropane afforded the expected isoxazole derivatives, as a result of nitrile oxide cycloadditions [21]. Microwave irradiation in the presence of catalytic PTSA has been successfully applied to condensations between methyl nitroacetate and dipolarophiles [22]. Nitroacetic esters have been converted into the corresponding furoxans with cold sulfuric acid [23], while phenylnitromethane and phenylacetylene in ethereal boron trifluoride etherate are reported to give 3,5-diphenylisoxazole [24]. 

Metal salts or complexes have a role in promoting dehydration of nitro compounds. Thus, 5-phenylisoxazole has been obtained in low yield from the lithium salt of phenylacetylene with nitromethane in dioxan at room temperature [24]. The complex tetrakis(triphenylphosphane) platinum(O) on treatment with nitromethane leads to fulminatobis(triphenylphosphane)platinum(II), possibly via CT-nitromethyls [25-27]. Cerium and other metal nitrates have been claimed to promote condensation of nitro compounds with alkenes [28]. More examples of condensations caused by transition metal salts are reported in Section 8.2.4. 

In the course of investigations on the radical addition of activated nitro compounds to unsaturated substrates promoted by Mn(ni) salts, several authors noticed the unexpected formation of isoxazole derivatives as side products. Thus, benzoylnitromethane with phenylacetylene gave 3-benzoyl-5-phenylisoxazole and nitroacetamides such as 14, with 1 -hexene the corresponding 5-butylisoxazolines 15 (Scheme 8.5) [79]. 

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