38418-19-8Relevant academic research and scientific papers
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
, p. 66 - 71 (2020/11/18)
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
Base-Promoted Amidation and Esterification of Imidazolium Salts via Acyl C-C bond Cleavage: Access to Aromatic Amides and Esters
Karthik, Shanmugam,Muthuvel, Karthick,Gandhi, Thirumanavelan
, p. 738 - 751 (2019/01/24)
Imidazolium salts have been effectively employed as suitable acyl transfer agents in amidation and esterification in organic synthesis. The weak acyl C(O)-C imidazolium bond was exploited to generate acyl electrophiles, which further react with amines and alcohols to afford amides and esters. The broad substrate scope of anilines and benzylic amines and base-promoted conditions are the benefits of this route. Interestingly, phenol, benzylic alcohols, and a biologically active alcohol can also be subjected to esterification under the optimized conditions.
Highly regioselective diels-alder reaction of 9-substituted anthracenes with citraconic anhydride
Khan, Ruhima,Singh, Thokchom Prasanta,Singh, Moirangthem Dhaneshwar
, p. 696 - 700 (2014/04/03)
The regioselectivity in the Diels-Alder reaction of 9-substituted anthracenes having electron-releasing substituents with citraconic anhydride has been investigated. The ortho regioisomer is preferred in all the cases with good yield. The reaction proceed
Post-functionalization of an Anderson-type polyoxomolybdate using a metal-free Diels-Alder click reaction
Yang, Hai-Kuan,Su, Ming-Ming,Ren, Li-Jun,Tang, Jing,Yan, Yu-Kun,Miao, Wen-Ke,Zheng, Ping,Wang, Wei
supporting information, p. 1381 - 1389 (2013/05/08)
Functionalization and post-functionalization of polyoxometalates (POMs) by organic groups or biological moieties can provide versatile platforms for creating novel functional hybrids with synergetic properties. Such materials can easily be envisioned as having many advanced applications in biology and materials science. Nowadays, the organic groups or biological moieties used for conjugation with POMs, can readily become increasingly complicated in terms of structure, size and properties. Accordingly, a major challenge lies in the development of efficient conjugation methods. In this work, we report our application of metal-free Diels-Alder click reactions under mild conditions to covalently link an Anderson-type polyoxomolybdate with some organic groups or biological moieties possessing complex structures or different properties. High coupling efficiencies and facile purification methods guarantee > 90 % yields. Clearly, this is an ideal methodology for the synthesis of the post-functionalized POM hybrids. With this technology now in hand, finding valuable applications for such post-functionalized POM hybrids will be a highly significant focus of future investigations. Copyright
Diazo preparation via dehydrogenation of hydrazones with "activated" DMSO
Javed, Muhammad I.,Brewer, Matthias
, p. 1789 - 1792 (2008/02/02)
We report that "activated" dimethyl sulfoxide efficiently dehydrogenates hydrazones to the respective diazo species at -78°C. Under optimized conditions, triethylamine hydrochloride is removed quantitatively by vacuum filtration to provide solutions of diazo compounds. Stable diazo species can be isolated in high yield, or alternatively, the direct treatment of these solutions with carboxylic acids provides esters.
