نتایج جستجو برای: selective alkylation

تعداد نتایج: 203893  

Journal: :Science 2015
Jenna L Jeffrey Jack A Terrett David W C MacMillan

The efficiency and selectivity of hydrogen atom transfer from organic molecules are often difficult to control in the presence of multiple potential hydrogen atom donors and acceptors. Here, we describe the mechanistic evaluation of a mode of catalytic activation that accomplishes the highly selective photoredox α-alkylation/lactonization of alcohols with methyl acrylate via a hydrogen atom tra...

2009
Robert Engel JaimeLee Iolani Rizzo Diego Montenegro Jay Leb Delroy Coleman Carolyn Hong Herby Jeanty Marie Thomas

Herein is reported the preparation of several series of symmetrical polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on several series of parent diamines where dimethylazonia functionalities are present, separated by a central structural unit, and pendant terminal chains. The resultant materials are of significant interest for a variety of purpo...

2007
Stefano Protti Daniele Dondi Maurizio Fagnoni Angelo Albini

A series of photochemical reactions are assessed under the environmental aspect by using Eissen and Metzger’s EATOS (environmental assessment tool for organic syntheses) method and are compared with strictly analogous thermal processes. These include C–C bond-forming reactions (arylation and alkylation) and selective oxidation and reduction reactions. In most cases, the photochemical method is ...

Journal: :Dalton transactions 2013
Mirtha A O Lourenço Renée Siegel Luís Mafra Paula Ferreira

N-alkylation reaction of amine functionalized phenylene moieties in crystal-like mesoporous silica is successfully achieved with about 87% of conversion in two reaction cycles. A potassium iodide catalyzed method commonly used for the selective N-monoalkylation of aniline is adapted and optimized to the N-monoalkylation reactions of the amine functionalized periodic mesoporous phenylene-silica ...

Journal: :Organic letters 2012
Bhaskar Reddy Kusuma Gary E L Brandt Brian S J Blagg

Cruentaren A, an antifungal benzolactone produced by the myxobacterium Byssovorax cruenta, is highly cytotoxic against various human cancer cell lines and a highly selective inhibitor of mitochondrial F-ATPase. A convergent and efficient synthesis of cruentaren A is reported, based upon a diastereoselective alkylation, a series of stereoselective aldol reactions utilizing Myers' pseudoephedrine...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید بهشتی 1356

چکیده ندارد.

2016
Saravanakumar Elangovan Jacob Neumann Jean-Baptiste Sortais Kathrin Junge Christophe Darcel Matthias Beller

Borrowing hydrogen (or hydrogen autotransfer) reactions represent straightforward and sustainable C-N bond-forming processes. In general, precious metal-based catalysts are employed for this effective transformation. In recent years, the use of earth abundant and cheap non-noble metal catalysts for this process attracted considerable attention in the scientific community. Here we show that the ...

Journal: :The Journal of antibiotics 1978
T L Nagabhurshan J J Wright A B Cooper W N Turner G H Miller

Chemical and photochemical oxidative methods of de-N-methylation of some gentamicins and sisomicins at the 3''-position are described. Selective acetylation of gentamicins and sisomicins at the 1, 3, 2' and 6' and of gentamicin B at the 1, 3, and 6'positions are achieved by treatment of the free bases with carbon dioxide prior to acetylation. De-N-methylation of the above selectively blocked ge...

Journal: :Chemistry 2010
Gregory T Bourne Daniel J Kuster Garland R Marshall

Phenylpyridal- and phenyldipyridal-based scaffolds have been designed and synthesized as novel helical peptide mimetics. The synthesis required optimisation and selective alkylation in producing 2,6-functionalized 3-hydroxypyridine derivatives for a convergent scheme. The pyridine analogues were coupled by a series of Suzuki/Stille types cross-coupling reactions. A series of biaryl and ter-aryl...

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