7148-07-4Relevant academic research and scientific papers
Enamine Organocatalysts for the Thiol-Michael Addition Reaction and Cross-Linking Polymerizations
Sinha, Jasmine,Soars, Shafer,Bowman, Christopher N.
, p. 1693 - 1701 (2021/02/16)
This article describes an efficient enamine organocatalyzed thiol-Michael click reaction and its broad application in cross-linking polymerizations. A series of enamines was shown to catalyze the thiol-Michael reaction via a nucleophilic pathway. By varying the amines as well as the ring size of the ketones, enamines were designed with broad ranges of nucleophilic character ranging from 11 to 17 on the Mayr nucleophilicity scale. Upon evaluating the enamines' organocatalytic effect on the kinetics of reactions involving a thiol and Michael acceptor, wherein butyl 3-mercaptopropionate and 1-hexyl acrylate were used as model reactants, enamines were shown to outperform their base analogs. The efficiency and overall reaction yields, ranging from 11 to 92% based on the thiol conversion, were highly dependent upon the nucleophilicity of the enamines employed. Interestingly, in situ formation of an enamine via photo-deprotection of an amine in the presence of cyclic ketones facilitated the thiol-Michael reaction efficiently while simultaneously enabling higher functional group conversion. This efficiency in the reaction kinetics and conversion was extended to multifunctional derivatives, which resulted in the formation of highly cross-linked polymers.
Synthesis of Medium-Sized Carbocycles via a Bidentate Lewis Acid-Catalyzed Inverse Electron-Demand Diels-Alder Reaction Followed by Photoinduced Ring-Opening
Ruhl, Julia,Ahles, Sebastian,Strauss, Marcel A.,Leonhardt, Christopher M.,Wegner, Hermann A.
supporting information, p. 2089 - 2093 (2021/04/05)
The combination of a Lewis acid-catalyzed inverse electron-demand Diels-Alder (IEDDA) reaction with a photoinduced ring-opening (PIRO) reaction in a domino process has been established as an efficient synthetic method to access medium-sized carbocycles. From readily available electron-rich and electron-poor phthalazines and enamines, respectively, as starting materials, various 9- and 11-membered carbocycles were prepared. This versatile transition-metal-free tool will be valuable for broadening the structural space in biologically active compounds and functional materials.
1 microwave-induced montmorillonite-mediated facile synthesis of enamines
Yadav, Ram Naresh,Banik, Indrani,Srivastava, Ashok Kumar,Ramos, Katherine,Banik, Bimal Krishna
, p. 249 - 254 (2020/01/08)
Montmorillonite clay-mediated simple and high yielding protocol for the synthesis of various enamines with secondary amines and ketones is developed under microwave condition. This protocol is very convenient to accesses the enamines from cyclic amines with various carbonyl compounds in high yield under mild reaction conditions with short reaction time.
Revisiting the role of acids and hydrogen bond acceptors in enamine formation
Hammond, Gerald B.,Lu, Zhichao,Xu, Bo
supporting information, p. 6849 - 6852 (2020/10/02)
A systematic investigation into the effects of acids and hydrogen bond acceptors on the reaction rates and equilibria of enamine formation is reported. Acids can accelerate the reaction but do not change the reaction equilibria. In comparison, hydrogen bond acceptors facilitate the enamine formation via their strong hydrogen bonding interaction with the water generated in the reaction.
Preparation of Hexahydrocarbazole Derivatives by Reductive Indolization
Christoffers, Jens,Dierks, Anna,Fliegel, Lukas,Schmidtmann, Marc
, p. 7164 - 7175 (2020/11/30)
The reductive indolization is a two-step protocol performed in one flask: First, the acid-mediated Fischer indolization of a cyclic ketone with phenylhydrazine forms an iminium ion which is subsequently reduced by a hydrido borate reagent to the indoline as the final product. We utilized this new strategy for the preparation of hexahydrocarbazole derivatives with a side chain in the quaternary C4a-position. Starting materials were several N1- and aryl-substituted phenylhydrazines and a cyclic ketone with propanoic ester moiety, which is the product of the conjugated addition of cyclohexanone to ethyl acrylate. Furthermore, benzannulated congeners as well as a pyrido[4,3-b]indole derivative were accessed. The hexahydrocarbazole defines a molecular scaffold with two points of diversification. Therefore, several derivatives at N9 and at the C4a-side chain were prepared.
Tf2O-Mediated Intermolecular Coupling of Secondary Amides with Enamines or Ketones: A Versatile and Direct Access to β-Enaminones
Liu, Yong-Peng,Zhu, Cheng-Jie,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
supporting information, p. 7169 - 7174 (2019/11/16)
Based on the Tf2O-mediated intermolecular reaction of secondary amides with enamines derived from ketones, a novel approach to β-enaminones has been developed. The reaction is widely functional group tolerant and highly chemoselective. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot condensation of secondary amides with ketones for NH β-enaminones synthesis.
Enantioselective Electrochemical Lactonization Using Chiral Iodoarenes as Mediators
Gao, Wen-Chao,Xiong, Zi-Yue,Pirhaghani, Shafigh,Wirth, Thomas
supporting information, p. 276 - 284 (2019/01/04)
The enantioselective electrochemical lactonization of diketo acid derivatives using chiral iodoarenes as redox mediators is reported for the first time. Good to high stereoselectivities are observed in the lactonization and also in intermolecular α-alkoxylations of diketo ester derivatives. This enantioselective process was then adapted to an electrochemical flow microreactor where only small amounts of supporting electrolyte were necessary.
Palladium-Catalysed Construction of All-Carbon Quaternary Centres with Propargylic Electrophiles: Challenges in the Simultaneous Control of Regio-, Chemo- and Enantioselectivity
Kenny, Miles,Schr?der, Sybrin P.,Taylor, Nicholas J.,Jackson, Paula,Kitson, Daniel J.,Franckevi?ius, Vilius
, p. 1796 - 1814 (2018/04/05)
This article describes the palladium-catalysed three-component coupling of 1,3-dicarbonyl compounds with nucleophiles and propargylic electrophiles for the generation of quaternary all-carbon centres in a single step, which necessitates the simultaneous control of regio-, chemo- and enantioselectivity. The use of propargyl enol carbonates, the source of two of the components, was found to be essential in maintaining high levels of regiocontrol and chemoselectivity, whereas a careful analysis of p K a trends of O-, C- and N-nucleophiles as the other coupling partner indicates that the highest levels of selectivity are likely to be obtained with relatively acidic species, such as phenols, 1,3-dicarbonyl compounds and aromatic N-heterocycles. Finally, studies towards the development of the catalytic enantioselective construction of quaternary all-carbon centres by means of alkenylation and allylic alkylation are disclosed.
Divergent pathways to isophthalates and naphthalate esters from methyl coumalate
Yu, Huangchao,Kraus, George A.
supporting information, p. 4008 - 4010 (2018/10/04)
Methyl coumalate readily reacts with enamines at ambient temperature to give lactones, which can be further transformed into isophthalates and tetrahydronaphthoates. Both cyclic and acyclic enamines show good reactivity. Dehydrogenation of tetrahydronaphthoate 4a was achieved on a hundred-gram scale.
SPIROFURANONE COMPOUNDS, DERIVATIVES THEREOF AND PROCESSES FOR THEIR PREPARATION
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Page/Page column 40; 41, (2016/08/23)
The present invention provides compounds comprising fused tricyclic backbone structure and processes for their preparation. The invention further provides compounds and compositions useful in the treatment of pain and any type of disorder or symptom associated therewith.
