4773-75-5Relevant academic research and scientific papers
Characterization of phenolic acid antimicrobial and antioxidant structure–property relationships
Beaman, Henry T.,Du, Changling,Liu, Jingyi,Monroe, Mary Beth B.
, (2020)
Plant-derived phenolic acids (PAs) are small molecules with antimicrobial, antioxidant, anti-inflammatory, and pro-coagulant properties. Their chemistry enables facile potential incorporation into biomaterial scaffolds to provide naturally-derived functionalities that could improve healing outcomes. While PAs have been previously characterized, their structure-property relationships in terms of antioxidant and antimicrobial properties are not well-understood, particularly in the context of their use in medical applications. To that end, a library of PAs with varied pendant groups was characterized here. It was found that increasing the number of radical-scavenging hydroxyl and methoxy groups on PAs increased antioxidant properties. All PAs showed some antimicrobial activity against the selected bacteria strains (Escherichia coli, Staphylococcus epidermidis (native and drug-resistant), and Staphylococcus aureus (native and drug-resistant)) at concentrations that are feasible for incorporation into polymeric biomaterials. In general, a trend of slightly decreased antimicrobial efficacy with increased number of pendant hydroxyl and methoxy groups was observed. The carboxylic acid group of a selection of PAs was modified with a polyurethane monomer analog. Modification did not greatly affect antioxidant or antimicrobial properties in comparison to unmodified controls, indicating that the carboxylic acid group of PAs can be altered without losing functionality. These results could be utilized for rational selection of phenolic moieties for use as therapeutics on their own or as part of a biomaterial scaffold with desired healing outcomes.
Ammonia-borane as a Catalyst for the Direct Amidation of Carboxylic Acids
Ramachandran, P. Veeraraghavan,Hamann, Henry J.
supporting information, p. 2938 - 2942 (2021/05/04)
Ammonia-borane serves as an efficient substoichiometric (10%) precatalyst for the direct amidation of both aromatic and aliphatic carboxylic acids. In situ generation of amine-boranes precedes the amidation and, unlike the amidation with stoichiometric amine-boranes, this process is facile with 1 equiv of the acid. This methodology has high functional group tolerance and chromatography-free purification but is not amenable for esterification. The latter feature has been exploited to prepare hydroxyl- and thiol-containing amides.
Sustainable triazine-based dehydro-condensation agents for amide synthesis
Sole, Roberto,Gatto, Vanessa,Conca, Silvia,Bardella, Noemi,Morandini, Andrea,Beghetto, Valentina
, (2021/04/26)
Conventional methods employed today for the synthesis of amides often lack of economic and environmental sustainability. Triazine-derived quaternary ammonium salts, e.g., 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM(Cl)), emerged as promising dehydro-condensation agents for amide synthesis, although suffering of limited stability and high costs. In the present work, a simple protocol for the synthesis of amides mediated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and a tert-amine has been described and data are compared to DMTMM(Cl) and other CDMT-derived quaternary ammonium salts (DMT-Ams(X), X: Cl? or ClO4?). Different tert-amines (Ams) were tested for the synthesis of various DMT-Ams(Cl), but only DMTMM(Cl) could be isolated and employed for dehydro-condensation reactions, while all CDMT/tert-amine systems tested were efficient as dehydro-condensation agents. Interestingly, in best reaction conditions, CDMT and 1,4-dimethylpiperazine gave N-phenethyl benzamide in 93% yield in 15 min, with up to half the amount of tert-amine consumption. The efficiency of CDMT/tert-amine was further compared to more stable triazine quaternary ammonium salts having a perchlorate counter anion (DMT-Ams(ClO4)). Overall CDMT/tert-amine systems appear to be a viable and more economical alternative to most dehydro-condensation agents employed today.
Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
supporting information, p. 5022 - 5037 (2021/05/04)
Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
Synthesis of Benzoisoselenazolones via Rh(III)-Catalyzed Direct Annulative Selenation by Using Elemental Selenium
Xu-Xu, Qing-Feng,Nishii, Yuji,Uetake, Yuta,Sakurai, Hidehiro,Miura, Masahiro
supporting information, p. 17952 - 17959 (2021/11/16)
Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium-catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X-ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study.
Iron-catalyzed oxidative amidation of acylhydrazines with amines
Wang, Yi-Jie,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
supporting information, (2021/08/18)
A new approach for amide bond formation via a mild and efficient Iron-catalyzed cross-coupling reaction of acylhydrazines and amines using TBHP as oxidant is described. This protocol is compatible with a wide range of amines and acylhydrazines. In addition, the synthetic application of the reaction is presented.
Zirconium Oxide-Catalyzed Direct Amidation of Unactivated Esters under Continuous-Flow Conditions
Rashed, Md. Nurnobi,Masuda, Koichiro,Ichitsuka, Tomohiro,Koumura, Nagatoshi,Sato, Kazuhiko,Kobayashi, Shū
supporting information, p. 2529 - 2535 (2021/02/01)
A sustainable and environmentally benign direct amidation reaction of unactivated esters with amines has been developed in a continuous-flow system. A commercially available amorphous zirconium oxide was found to be an efficient catalyst for this reaction. While the typical amidation of esters with amines requires a stoichiometric amount of a promoter or metal activator, the present continuous-flow method enabled the direct amidation reaction under additive-free conditions with an extensive diversity towards various functional groups. High yields of the products were obtained with a nearly equimolar proportion of starting materials to reduce byproduct formation, which renders this process applicable for use in a sequential-flow system. (Figure presented.).
A practical and sustainable protocol for direct amidation of unactivated esters under transition-metal-free and solvent-free conditions
Chen, Cheng,Cheng, Hua,Du, Min-Chen,Qian, Liang,Qin, Xin,Sang, Wei,Yao, Wei-Zhong,Yuan, Ye,Zhang, Rui
supporting information, p. 3972 - 3982 (2021/06/17)
In this paper, a NaOtBu-mediated synthesis approach was developed for direct amidation of unactivated esters with amines under transition-metal-free and solvent-free conditions, affording a series of amides in good to excellent yields at room temperature. In particular, an environmentally friendly and practical workup procedure, which circumvents the use of organic solvents and chromatography in most cases, was disclosed. Moreover, the gram-scale production of representative products3a,3wand3auwas efficiently realized by applying operationally simple, sustainable and practical procedures. Furthermore, this approach was also applicable to the synthesis of valuable molecules such as moclobemide (a powerful antidepressant), benodanil and fenfuram (two commercial agricultural fungicides). These results demonstrate that this protocol has the potential to streamline amide synthesis in industry. Meanwhile, quantitative green metrics of all the target products were evaluated, implying that the present protocol is advantageous over the reported ones in terms of environmental friendliness and sustainability. Finally, additional experiments and computational calculations were carried out to elucidate the mechanistic insight of this transformation, and one plausible mechanism was provided on the basis of these results and the related literature reports.
Direct Amidation of Esters by Ball Milling**
Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
supporting information, p. 21868 - 21874 (2021/09/02)
The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
Metal-free transamidation of benzoylpyrrolidin-2-one and amines under aqueous conditions
Joseph, Devaneyan,Lee, Sunwoo,Park, Myeong Seong
supporting information, p. 6227 - 6232 (2021/07/28)
N-Acyl lactam amides, such as benzoylpyrrolidin-2-one, benzoylpiperidin-2-one, and benzoylazepan-2-one reacted with amines in the presence of DTBP and TBAI to afford the transamidated products in good yields. The reactions were conducted under aqueous conditions and good functional group tolerance was achieved. Both aliphatic and aromatic primary amines displayed good activity under metal-free conditions. A radical reaction pathway is proposed.
