790-53-4Relevant academic research and scientific papers
Divergent Rearrangements of Vinylcyclopropane into Skipped Diene and Cyclopentene: Mechanism, Scope, and Limitations
Delbrassinne, Arnaud,Richald, Maximilien,Janssens, Julien,Robiette, Rapha?l
supporting information, p. 2862 - 2868 (2021/06/11)
Vinylcyclopropanes are versatile intermediates in organic synthesis which undergo various rearrangements. We report a new rearrangement of vinylcyclopropane into skipped diene. A detailed mechanistic study revealed that this transformation involves regioselective ring-opening of the cyclopropane ring followed by 1,2-migration of one of the cyclopropane substituents. Interestingly, our investigations showed that skipped diene is the kinetic product of the process but formation of a more stable cyclopentene is also accessible. The fundamental understanding of the processes involved enabled the development of divergent methodologies allowing to obtain cyclopentene or skipped diene from vinylcyclopropane in a selective and controlled manner.
Ball-Milling-Enabled Reactivity of Manganese Metal**
Bolt, Robert R. A.,Browne, Duncan L.,Howard, Joseph L.,Khan, Adam,Magri, Giuseppina,Morrill, Louis C.,Nicholson, William I.,Richards, Emma,Seastram, Alex C.
supporting information, p. 23128 - 23133 (2021/09/20)
Efforts to generate organomanganese reagents under ball-milling conditions have led to the serendipitous discovery that manganese metal can mediate the reductive dimerization of arylidene malonates. The newly uncovered process has been optimized and its mechanism explored using CV measurements, radical trapping experiments, EPR spectroscopy, and solution control reactions. This unique reactivity can also be translated to solution whereupon pre-milling of the manganese is required.
Electrochemical Generation of a Nonstabilized Azomethine Ylide: Access to Substituted N-Heterocycles
Kumar, Rakesh,Banerjee, Prabal
, p. 16104 - 16113 (2021/11/18)
Azomethine ylides are fascinating 1,3-dipoles for [3 + 2] cycloaddition reactions toward the construction ofN-heterocycles. Herein, an efficient and environmentally benign electrochemical approach for the generation of a nonstabilized azomethine ylide has been established under metal-free and external oxidant-free conditions. The resulting 1,3-dipole undergoes a [3 + 2] cycloaddition reaction with olefins. This electrosynthetic methodology indulges a straightforward and facile approach for the construction of substituted pyrrolidines.
Electricity Driven 1,3-Oxohydroxylation of Donor-Acceptor Cyclopropanes: a Mild and Straightforward Access to β-Hydroxy Ketones
Banerjee, Prabal,Maajid Taily, Irshad,Saha, Debarshi
supporting information, p. 5053 - 5057 (2021/09/30)
An unprecedented external oxidant-free electrochemical protocol for 1, 3-oxohydroxylation of donor-acceptor cyclopropane is disclosed. The strategy encompasses the activation of the labile π-electron cloud of the aryl ring to cleave the strained Csp3?Csp3 bond of cyclopropane to afford the β-hydroxy ketones via insertion of molecular oxygen. More significantly, based on the detailed mechanistic investigations and cyclic voltammetry experiments, a plausible mechanism is proposed.
A facile, efficient and solvent-free titanium (IV) ethoxide catalysed knoevenagel condensation of aldehydes and active methylenes
Ramaiah, Manjunatha M.,Shivananju, Nanjunda Swamy,Shubha, Priya Babu
, p. 107 - 115 (2020/02/04)
Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.
Co-Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine-catalyzed Organic Reactions
Riva, Laura,Punta, Carlo,Sacchetti, Alessandro
, p. 6214 - 6222 (2020/10/02)
Heterogeneous catalysts prepared from biomass waste sources are attracting increasing interest. The reasons rely on the possibility of combining the virtuous approach of circular economy with the consolidated advantages of heterogeneous catalysis, namely the recycling of the system and the possibility to drive selectivity towards desired products. Herein we report a highly porous cellulose-based nanosponge (CNS) and its use as a recoverable catalyst for Henry and Knoevenagel reactions, two classical amino-catalyzed transformations. The material is obtained by cross-linking between TEMPO-oxidized cellulose nanofibers (TOCNF) and branched polyethyleneimine 25 kDa (bPEI) in the presence of citric acid. CNS have been developed as sorbent materials for water remediation but their use as heterogeneous catalysts was never investigated. The fully characterized micro- and nano-porous system guarantees a complete penetration of CNS, allowing reagents to diffuse within. Indeed, by modulating reaction conditions (catalyst loading, temperature, solvent, microwave versus conventional heating, relative ratio of reagents) it was possible to drive selectivity towards the desired products, while maintaining high efficiency in terms of conversion. The catalyst could be re-used several times without losing in catalytic efficiency. In most cases the products’ distribution is quite different from homogeneous conditions, this much more emphasizing the importance of this heterogeneous solution.
Solvent-Free FeCl3-Assisted Electrophilic Fluorine-Catalyzed Knoevenagel Condensation to Yield α,β-Unsaturated Dicarbonyl Compounds and Coumarins
Yang, Lu,Zhu, Jiang,Xie, Fukai,Peng, Xiaoshi,Lin, Bin,Liu, Yongxiang,Cheng, Maosheng
, p. 1053 - 1060 (2019/09/06)
A highly environmentally friendly procedure was developed for the Knoevenagel condensation of aromatic aldehydes with diethyl malonate in the presence of FeCl3 and N-fluorobenzenesulfonimide as a source of electrophilic fluorine under solvent-free conditions. The scope of the reaction was explored using commercially available substrates. The reaction with substituted salicylaldehydes afforded the corresponding coumarin derivatives which attract interest due to their potential medicinal importance.
Metal free biomimetic deaminative direct C-C coupling of unprotected primary amines with active methylene compounds
Ghosh, Santanu,Jana, Chandan K.
supporting information, p. 10153 - 10157 (2019/12/26)
An unprecedented direct C-C coupling reaction of unprotected primary amines with active methylene compounds is reported. The reaction involves a biomimetic deamination of amines which was achieved under conditions free of metallic reagents and strong oxidizing agents. A wide range of primary amines was reacted with different active methylene compounds to provide structurally diverse trisubstituted alkenes and dihydropyridines. A kinetic study revealed an activation barrier of 10.1 kcal mol-1 for the conversion of a key intermediate of the reaction.
Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate
Coutant, Eloi P.,Hervin, Vincent,Gagnot, Glwadys,Ford, Candice,Baatallah, Racha,Janin, Yves L.
supporting information, p. 2853 - 2860 (2018/11/26)
We have explored here the scope of the age-old diethyl malonate-based accesses to α-amino esters involving Knoevenagel condensations of diethyl malonate on aldehydes, reductions of the resulting alkylidenemalonates, the preparation of the corresponding α-hydroxyimino esters and their final reduction. This synthetic pathway turned out to be general although some unexpected limitations were encountered. The synthetic modifications of some of the intermediates - using Suzuki-Miyaura coupling or cycloadditions - before undertaking the oximation step - provided accesses to further α-amino esters. Moreover, other pathways to α-hydroxyimino esters were explored including an attempt to improve the cycloadditions between ethyl β-bromo-α-hydroxyiminocarboxylate and various alkylfuranes.
Design, synthesis, and biological evaluation of some novel indolizine derivatives as dual cyclooxygenase and lipoxygenase inhibitor for anti-inflammatory activity
Shrivastava, Sushant K.,Srivastava, Pavan,Bandresh, Robin,Tripathi, Prabhash Nath,Tripathi, Avanish
, p. 4424 - 4432 (2017/07/22)
Some novel indolizine derivatives were synthesized by bioisosteric modification of imidazo[1,2-a]pyridine for anti-inflammatory activity. The physicochemical characterization and structure of compounds were elucidated by state of the art spectroscopic technique. Induced fit docking was performed for initial screening to elucidate the interactions with corresponding amino acids of cyclooxygenase (COX-1, COX-2) and lipoxygenase (LOX) enzymes. The target compounds 53–60 were then evaluated against in vivo carrageenan and arachidonic acid induced rat paw edema models for anti-inflammatory activity. Amongst all the synthesized derivatives, compound 56 showed the significant anti-inflammatory activity in both rat paw edema models with very less ulcerogenic liability in comparison to standard diclofenac, celecoxib, and zileuton. The compounds 56 was further assessed to observe in vitro enzyme inhibition assay on both cyclooxygenase and lipoxygenase enzyme where it showed a preferential and selective non-competitive enzyme inhibition towards the COX-2 (IC50?=?14.91?μM, Ki?=?0.72?μM) over COX-1 (IC50?>?50?μM) and a significant non-competitive inhibition of soybean lipoxygenase enzyme (IC50?=?13.09?μM, Ki?=?0.92?μM). Thus, in silico, in vivo, and in vitro findings suggested that the synthesized indolizine compound 56 has a dual COX-2 and LOX inhibition characteristic and parallel in vivo anti-inflammatory activity in comparison to the standard drugs.
