306-44-5Relevant academic research and scientific papers
Involvement of the Enol Tautomers in the Nitrosation of Ketones
Leis, J. Ramon,Pena, M. Elena,Williams, D. Lyn H.
, p. 45 - 47 (1987)
Nitrosation of ketones involves reaction of the enol form; the rate limiting step can be either formation of the enol, or its reaction with the nitrosating agent.
Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts
Ma, Xiaoshen,Dang, Hester,Rose, John A.,Rablen, Paul,Herzon, Seth B.
supporting information, p. 5998 - 6007 (2017/05/04)
We report the first reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%). N-Methoxy imidazolium salts are accessible in three steps from commercial amines (50-85%). In total 36 discrete methoxyheteroarenium salts bearing electron-donating, electron-withdrawing, alkyl, aryl, halogen, and haloalkyl substituents were prepared (several in multigram quantities) and coupled with 38 different alkenes. The transformations proceed under neutral conditions at ambient temperature, provide monoalkylation products exclusively, and form a single alkene addition regioisomer. Preparatively useful and complementary site selectivities in the addition of secondary and tertiary radicals to pyidinium salts are documented: harder secondary radicals favor C-2 addition (2->10:1), while softer tertiary radicals favor bond formation to C-4 (4.7->29:1). A diene possessing a 1,2-disubstituted and 2,2-disubstituted alkene undergoes hydropyridylation at the latter exclusively (61%) suggesting useful site selectivities can be obtained in polyene substrates. The methoxypyridinium salts can also be employed in dehydrogenative arylation, borono-Minisci, and tandem arylation processes. Mechanistic studies support the involvement of a radical process.
Water-Assisted Nitrile Oxide Cycloadditions: Synthesis of Isoxazoles and Stereoselective Syntheses of Isoxazolines and 1,2,4-Oxadiazoles
Kesornpun, Chatchai,Aree, Thammarat,Mahidol, Chulabhorn,Ruchirawat, Somsak,Kittakoop, Prasat
supporting information, p. 3997 - 4001 (2016/03/19)
Conventional methods generate nitrile oxides from oxime halides in organic solvents under basic conditions. However, the present work revealed that water-assisted generation of nitrile oxides proceeds under mild acidic conditions (pH 4-5). Cycloadditions of nitrile oxides with alkynes and alkenes easily occurred in water without using catalysts, thus yielding isoxazoles and isoxazolines, respectively, with excellent stereoselectivity toward five- and six-membered cyclic alkenes. A double stereoselective cycloaddition of two units of a nitrile oxide with cyclohexene was also achieved, thus yielding 1,2,4-oxadiazole derivatives having a unique hybrid isoxazoline-oxadiazole skeleton. Enantiomerically pure isoxazolines were prepared from monoterpenes with a ring strain. In one case, the isoxazoline with a butterfly-like structure was simply prepared, and it might be used as a ligand in asymmetric catalysis.
Sterilization compound and preparation method and application thereof
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Paragraph 0021; 0047; 0048; 0049, (2016/10/27)
The invention relates to the field of agricultural plant protection, and particularly relates to a sterilization compound and a preparation method and an application thereof. The compound has the structure represented by a formula defined in the specification, wherein R is selected from one of components defined in the specification; the compound has excellent bacteriostatic activity on potato phytophthora infestans, phytophthora capsici, phytophthora nicotianae, peronophthora litchii, pseudoperonospora cubensis and other plant pathogenic oomycetes, and has broad application prospects in prevention and control of oomycete diseases.
First kinetic discrimination between carbon and oxygen reactivity of enols
Garcia-Rio, Luis,Mejuto, Juan C.,Parajo, Mercedes,Perez-Lorenzo, Moises
scheme or table, p. 8198 - 8205 (2009/04/04)
(Chemical Equation Presented) Nitrosation of enols shows a well-differentiated behavior depending on whether the reaction proceeds through the carbon (nucleophilic catalysis is observed) or the oxygen atom (general acid-base catalysis is observed). This is due to the different operating mechanisms for C- and O-nitrosation. Nitrosation of acetylacetone (AcAc) shows a simultaneous nucleophilic and acid-base catalysis. This simultaneous catalysis constitutes the first kinetic evidence of two independent reactions on the carbon and oxygen atom of an enol. The following kinetic study allows us to determine the rate constants for both reaction pathways. A similar reactivity of the nucleophilic centers with the nitrosonium ion is observed.
A new and general method for the synthesis of quinoxalines
Tajbakhsh,Bakooie,Ghassemzadeh,Beheshtiha,Heravi
, p. 1232 - 1233 (2007/10/03)
A new and general synthetic method for the preparation of 2,3-disubstituted quinoxalines is described. Treatment of ?-phenylenediamine with α-ketoaldoximes in ethanol affords 2,3-disubstituted quinoxalines in one-step reaction.
Synthesis of highly functionalized pyrazines by ortho-lithiation reactions. Pyrazine ladder polymers
Zhang, Carol Y.,Tour, James M.
, p. 8783 - 8790 (2007/10/03)
Several novel transformations on sensitive pyrazine cores are disclosed while preparing monomers for condensation polymerizations to planar polypyrazines. Two pyrazine monomers for the step growth polymerization are prepared starting from ethyl acetoacetate and proceeding via pyrazine-2,5-dicarboxylic acid as the common intermediate. The dicarboxylic acid serves as the key intermediate for the preparation of both the A and B components for the step-growth polymerization. A bis(Curtius) rearrangement followed by tert-butyl alcohol capture of the diisocyanate effects the high-yielding conversion of carbonyl moieties to the tert-butoxycarbonyl-protected aryldiamine. Since electrophilic halogenation of the pyrazine nucleus was unsuccessful due to the inherent electron deficiency of pyrazines, a directed ortho-metalation is disclosed using tert-butoxycarbonyl-protected amines and neopentyl glycol acetals as the metalation directing groups. Pd/Cu-catalyzed couplings of diiodopyrazines with distannylpyrazines are utilized for the polymerization schemes. This approach permits the ladder linkages of the planar polymers to (i) form in high yields upon ZnCl2 activation once the polymer backbone is intact, (ii) be substituted so that the newly formed polypyrazines are soluble, unlike many other aromatic ladder polymers, and (iii) contain double-bonded ladder units to keep the consecutive aryl moieties planar which maximizes extended π-conjugation through the polymer backbones, thereby increasing the bandwidths and lowering the optical band gaps.
Pteridine nucleotide analogs as fluorescent DNA probes
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, (2008/06/13)
The invention provides novel pteridine nucleotides which are highly fluorescent under physiological conditions and which may be used in the chemical synthesis of fluorescent oligonucleotidcs. The invention further provides for fluorescent oligonucleotides comprising one or more pteridine nucleotides. In addition the invention provides for pteridine nucleotide triphosphates which may be used as the constituent monomers in DNA amplification procedures.
Nitrosation of acetone with nitric oxide using iron(III) pentacyano complexes
Gol'tsov, Yu. G.,Zhilinskaya, V. V.
, p. 1367 - 1369 (2007/10/02)
We have studied the nitrosation of acetone by nitric oxide in an aqueous alkaline solution in the presence of pentacyano complexes of iron(III).The catalytic activity of the iron(III) pentacyanides towards this reaction is higher than that of iron(II) pentacyanides.
Nitrosation of acetone by nitric oxide using pentacyano complexes of iron(II)
Gol'tsov, Yu. G.,Zhilinskaya, V. V.
, p. 1596 - 1598 (2007/10/02)
The nitrosation of acetone by nitric oxide in an aqueous alkaline solution in the presence of pentacyano complexes of iron(II) has been studied spectrophotometrically.It is shown that the catalytic activity of the pentacyanides towards this reaction depends on the nature of the sixth ligand in the coordination sphere of the complex.
