نتایج جستجو برای: amidines
تعداد نتایج: 390 فیلتر نتایج به سال:
Novel bidentate amidines were designed and synthesized as easily available electron-donating N-ligands for Ni0-mediated coupling of carbon dioxide with alkynes or allenes, and high regioselectivity was achieved even for the carboxylation of aryl substituted internal alkynes.
An efficient copper-catalyzed three-component cyclization for the construction of highly functionalized pyrimidine derivatives from readily available amidines, styrenes and fluoroalkyl halides is developed. This protocol distinguishes itself by the formation of three new C-C/C-N bonds and a new six-membered ring through a radical addition/oxidation/cyclization sequence in a one-pot manner.
Direct electrochemical synthesis of sulfonyl amidines from aliphatic amines and sulfonyl azides was realized with good to excellent yields. Traditional tertiary amine substrates were broadened to secondary and primary amines. The reaction intermediates were observed and a reaction mechanism was proposed and discussed.
A fast and convenient synthesis of aryl amidines starting from carboxylic acids and cyanamides is reported. The reaction was achieved by palladium(II)-catalysis in a one-step microwave protocol using [Pd(O2 CCF3 )2 ], 6-methyl-2,2'-bipyridyl and trifluoroacetic acid (TFA) in N-methylpyrrolidinone (NMP), providing the corresponding aryl amidines in moderate to excellent yields. The protocol is v...
Diastereoselective anti-aminooxygenation and anti-diamination of alkenes with amidines were enabled by hypervalent iodine(III) reagents such as PhI(OCOR)2 and PhI(NMs2)2, respectively. The present transformation offers diastereochemically pure dihydroimidazoles divergently from E- and Z-alkenes.
The syntheses of several polyazaheterocycles are demonstrated. The cyclocondensation reactions between β-enaminodiketones [CCl3C(O)C(=CNMe2)C(O)-CO2Et] and aromatic amidines resulted in glyoxalate-substituted pyrido[1,2-a]pyrimidinone, thiazolo[3,2-a]pyrimidinone and pyrimido[1,2-a]benzimidazole. Pyrazinones and quinoxalinones were obtained through the reaction of these glyoxalates with ethylen...
The scope of the [4 + 2] cycloaddition reactions of substituted 1,2,3-triazines, bearing noncomplementary substitution with electron-withdrawing groups at C4 and/or C6, is described. The studies define key electronic and steric effects of substituents impacting the reactivity, mode (C4/N1 vs C5/N2), and regioselectivity of the cycloaddition reactions of 1,2,3-triazines with amidines, enamines, ...
Amidines are special nitrogen analogues of the carboxylic acid, containing two N of different functionality. One is formally single bonded like-amino nitrogen (N) and the other is a formally double-bonded imino nitrogen (N), where protonation occurs first. The pKa’s of amidines vary from neutral to slightly acidic (pKa ranges from 4.4 to 14) depending on their substitution pattern. Amidines are...
A robust protocol for the CuI-catalysed arylation of amidines is presented. Whilst the initially identified conditions were useful for benzamidine-derived substrates, difficulties were encountered with more complex substrates. This problem was overcome following a change in ligand type, enabling the synthesis of analogues of the chemical tool, blebbistatin.
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