نتایج جستجو برای: selective alkylation
تعداد نتایج: 203893 فیلتر نتایج به سال:
Despite notable recent efforts, a catalytic and convenient strategy for the direct alkylation of unactivated allylic or benzylic sp C–H bonds remains a formidable challenge facing the synthesis community. We herein report an unprecedented allylic/benzylic alkylation using only an organo-photoredox catalyst, which enables coupling of a broad scope of alkenes/arenes and electron-deficient alkenes...
A general method for intermolecular allylic C-H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C-H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic ...
Nitriles were found to be highly effective alkylating reagents for the selective N-alkylation of amines under catalytic hydrogenation conditions. For the aromatic primary amines, the corresponding secondary amines were selectively obtained under Pd/C-catalyzed hydrogenation conditions. Although the use of electron poor aromatic amines or bulky nitriles showed a lower reactivity toward the reduc...
Comparing the reactivity of the related lithium zincates [(THF)LiZn(TMP)(t)Bu(2)] (1) and [(PMDETA)LiZn(t)Bu(3)] (2) towards pyrazine discloses two new bimetallic approaches for the selective 2,5-dideprotonation and room temperature C-H alkylation of this sensitive heterocycle.
The synthesis of 9,9'-[1,2-ethanediylbis(oxymethylene)]bis-2-amino-1,9-dihydro-6H-purin-6-one, a minor impurity of acyclovir, is described. Starting with commercial N-(9-acetyl-6-oxo-1H-purin-2-yl)acetamide, the process uses an acid catalysed phase transfer catalysis (PTC) process to produce the selective alkylation at the 9 position of the guanine ring.
Alkylation of biphenyl with 1-octene was investigated using ((Al+C3H7Cl)+C2H4) catalysts. The catalytic activity of ((Al+C3H7Cl)+C2H4) for the alkylation was studied at different temperatures, mol ratios of biphenyl to 1-octene, reaction times and catalyst concentrations. It was shown that using this catalyst has more advantagous than another catalysts. Experiments show that by increasing t...
Shape selective xylene production is very important in the polymer industry because of its extensive use as raw material for monomer preparation. The acidity associated with the Lewis and Broensted centers present in the pillars interlayered clay and its textural properties allows good catalytic activity and shape selectivity toward p-xylene production. So, in the present study, ultrasonic and ...
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