- Controlled meta-Selective C-H Mono- And Di-Olefination of Mandelic Acid Derivatives
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Mandelic acids represent a key structural motif present in many drug molecules. Herein, we report the controlled meta-selective mono- and diolefination of mandelic acids by the careful design of the substrate and oxidant. Furthermore, free meta-functional
- Muthuraja, Perumal,Usman, Rahamdil,Sajeev, Revathy,Gopinath, Purushothaman
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p. 6014 - 6018
(2021/08/03)
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- A Combined Experimental–Theoretical Study on Diels-Alder Reaction with Bio-Based Furfural: Towards Renewable Aromatics
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The synthesis of relevant renewable aromatics from bio-based furfural derivatives and cheap alkenes is carried out by using a Diels-Alder/aromatization sequence. The prediction and the control of the ortho/meta selectivity in the Diels-Alder step is an important issue to pave the way to a wide range of renewable aromatics, but it remains a challenging task. A combined experimental-theoretical approach reveals that, as a general trend, ortho and meta cycloadducts are the kinetic and thermodynamic products, respectively. The nature of substituents, both on the dienes and dienophiles, significantly impacts the feasibility of the reaction, through a modulation on the nucleo- and electrophilicity of the reagents, as well as the ortho/meta ratio. We show that the ortho/meta selectivity at the reaction equilibrium stems from a subtle interplay between charge interactions, favoring the ortho products, and steric interactions, favoring the meta isomers. This work also points towards a path to optimize the aromatization step.
- van Scodeller,De Oliveira Vigier, Karine,Muller, Eric,Ma, Changru,Guégan, Frédéric,Wischert, Raphael,Jér?me, Fran?ois
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p. 313 - 323
(2020/10/19)
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- The reductive deaminative conversion of nitriles to alcohols using: Para -formaldehyde in aqueous solution
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We report herein, for the first time, the application of para-formaldehyde (pFA) to the reductive deamination of both aliphatic and aromatic nitriles in aqueous solution under transfer hydrogenation conditions. A broad range of primary alcohols have been synthesized selectively with very good to excellent yields under the optimized conditions. The study disclosed that the air-stable, inexpensive and commercially available catalyst [Ru(p-cymene)Cl2]2 acts as the catalyst precursor in this reaction, converting to other more active catalytic species in the presence of pFA, resulting in its degradation to CO2 and H2. Nitriles are also showed to play a dual role in this transformation, both as a substrate and as a ligand, where the dimeric catalyst structures convert to monomeric ones upon the coordination of nitrile molecules.
- Tavakoli, Ghazal,Prechtl, Martin H. G.
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p. 6092 - 6101
(2019/11/11)
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- Synthesis of Renewable meta-Xylylenediamine from Biomass-Derived Furfural
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We report the synthesis of biomass-derived functionalized aromatic chemicals from furfural, a building block nowadays available in large scale from low-cost biomass. The scientific strategy relies on a Diels–Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. In particular, through this route, we describe the synthesis of renewably sourced meta-xylylenediamine (MXD). Transposition of this work to other furfural-derived chemicals is also discussed and reveals that functionalized biomass-derived aromatics (benzaldehyde, benzylamine, etc.) can be potentially produced, according to this route.
- Scodeller, Ivan,Mansouri, Samir,Morvan, Didier,Muller, Eric,de Oliveira Vigier, Karine,Wischert, Raphael,Jér?me, Fran?ois
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supporting information
p. 10510 - 10514
(2018/08/17)
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- Ex situ generation of stoichiometric HCN and its application in the Pd-catalysed cyanation of aryl bromides: Evidence for a transmetallation step between two oxidative addition Pd-complexes
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A protocol for the Pd-catalysed cyanation of aryl bromides using near stoichiometric and gaseous hydrogen cyanide is reported for the first time. A two-chamber reactor was adopted for the safe liberation of ex situ generated HCN in a closed environment, which proved highly efficient in the Ni-catalysed hydrocyanation as the test reaction. Subsequently, this setup was exploited for converting a range of aryl and heteroaryl bromides (28 examples) directly into the corresponding benzonitriles in high yields, without the need for cyanide salts. Cyanation was achieved employing the Pd(0) precatalyst, P(tBu)3-Pd-G3 and a weak base, potassium acetate, in a dioxane-water solvent mixture. The methodology was also suitable for the synthesis of 13C-labelled benzonitriles with ex situ generated 13C-hydrogen cyanide. Stoichiometric studies with the metal complexes were undertaken to delineate the mechanism for this catalytic transformation. Treatment of Pd(P(tBu)3)2 with H13CN in THF provided two Pd-hydride complexes, (P(tBu)3)2Pd(H)(13CN), and [(P(tBu)3)Pd(H)]2Pd(13CN)4, both of which were isolated and characterised by NMR spectroscopy and X-ray crystal structure analysis. When the same reaction was performed in a THF : water mixture in the presence of KOAc, only (P(tBu)3)2Pd(H)(13CN) was formed. Subjection of this cyano hydride metal complex with the oxidative addition complex (P(tBu)3)Pd(Ph)(Br) in a 1 : 1 ratio in THF led to a transmetallation step with the formation of (P(tBu)3)2Pd(H)(Br) and 13C-benzonitrile from a reductive elimination step. These experiments suggest the possibility of a catalytic cycle involving initially the formation of two Pd(ii)-species from the oxidative addition of LnPd(0) into HCN and an aryl bromide followed by a transmetallation step to LnPd(Ar)(CN) and LnPd(H)(Br), which both reductively eliminate, the latter in the presence of KOAc, to generate the benzonitrile and LnPd(0).
- Kristensen, Steffan K.,Eikeland, Espen Z.,Taarning, Esben,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 8094 - 8105
(2017/11/27)
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- Discovery of N-Substituted (2-Phenylcyclopropyl)methylamines as Functionally Selective Serotonin 2C Receptor Agonists for Potential Use as Antipsychotic Medications
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A series of N-substituted (2-phenylcyclopropyl)methylamines were designed and synthesized, with the aim of finding serotonin 2C (5-HT2C)-selective agonists with a preference for Gq signaling. A number of these compounds exhibit 5-HT2C selectivity with a preference for Gq-mediated signaling compared with β-arrestin recruitment. Furthermore, the N-methyl compound (+)-15a, which displayed an EC50 of 23 nM in the calcium flux assay while showing no β-arrestin recruitment activity, is the most functionally selective 5-HT2C agonist reported to date. The N-benzyl compound (+)-19, which showed an EC50 of 24 nM at the 5-HT2C receptor, is fully selective over the 5-HT2B receptor. In an amphetamine-induced hyperactivity model, compound (+)-19 showed significant antipsychotic-drug-like activity. These novel compounds shed light on the role of functional selectivity at the 5-HT2C receptor with respect to antipsychotic activity.
- Zhang, Guiping,Cheng, Jianjun,McCorvy, John D.,Lorello, Paul J.,Caldarone, Barbara J.,Roth, Bryan L.,Kozikowski, Alan P.
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supporting information
p. 6273 - 6288
(2017/08/02)
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- Selective catalytic hydrogenation of nitriles to primary amines using iron pincer complexes
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The selective catalytic hydrogenation of nitriles to primary amines with the well-defined Fe(PNPCy) pincer complex 2 is reported. This iron pincer catalyst shows superior catalytic activity and selectivity in the reduction of various nitriles including industrially relevant adipodinitrile in high yields under relatively mild conditions.
- Lange,Elangovan,Cordes,Spannenberg,Jiao,Junge,Bachmann,Scalone,Topf,Junge,Beller
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p. 4768 - 4772
(2016/07/11)
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- Rhodium(iii)-catalyzed olefinic C-H alkynylation of enamides at room temperature
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Rh(iii)-catalyzed C-H olefinic alkynylation of enamides for the stereospecific construction of synthetically useful Z-type enynamides is reported. This protocol displays good functionality tolerance and operational simplicity thus providing an alternative synthetic opportunity for the ease of access to specific 1,3-enyne derivatives.
- Feng, Chao,Feng, Daming,Loh, Teck-Peng
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supporting information
p. 9865 - 9868
(2014/08/18)
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- Ultrasounds in melted poly(ethylene glycol) promote copper-catalyzed cyanation of aryl halides with K4[Fe(CN)6]
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Melted poly(ethylene glycols) (PEGs) were used for the first time as solvent for the sonochemically promoted cyanation of aryl halides employing inexpensive and safe K4[Fe(CN)6] and a relatively low amount of Cu-based catalyst. The Mw (weight-average polymer molecular weight) of PEG proved to notably influence the substrate conversion, which is indicative of a strong dependence of the sonication efficacy on solvent properties. Gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) contributed to the characterization of the polymer and the elucidation of the catalytic system. Off the PEG: Melted poly(ethylene glycol)s (PEG)s were used for the first time as solvent for the sonochemical cyanation of aryl halides using K 4[Fe(CN)6] and a relatively low amount of Cu catalyst (5 %). The weight-average molecular weight of PEG was proven to exert a notable influence on conversion, and CuI proved to be the most efficient catalyst, affording good results within short reaction times with the use of aryl iodides and activated aryl bromides as substrates.
- Giachi, Guido,Frediani, Marco,Oberhauser, Werner,Lamaty, Frederic,Martinez, Jean,Colacino, Evelina
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p. 919 - 924
(2014/03/21)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Substrate profiling and aldehyde dismutase activity of the Kvβ2 subunit of the mammalian Kv1 potassium channel
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Voltage-dependent potassium channels (Kv) are involved in various cellular signalling processes by governing the membrane potential of excitable cells. The cytosolic face of these α subunit-containing channels is associated with β subunits that can modulate channel responses. Surprisingly, the β subunit of the mammalian Kv1 channels, Kvβ2, has a high level of sequence homology with the aldo-keto reductase (AKR) superfamily of proteins. Recent studies have shown that Kvβ2 can catalyze the reduction of aldehydes and, most significantly, that channel function is modulated when Kvβ2-bound NADPH is concomitantly oxidized. As a result, the redox chemistry of this subunit is crucial to understanding its role in K+ channel modulation. The present study has extended knowledge of the substrate profile of this subunit using a single turnover fluorimetric assay. Kvβ2 was found to catalyse the reduction of aromatic aldehyde substrates such as 2, 3 and 4-nitrobenzaldehydes, 4-hydroxybenzaldehyde, pyridine 2-aldehyde and benzaldehyde. The presence of an electron withdrawing group at the position para to the aldehyde in aromatic compounds facilitated reduction. Aliphatic aldehydes proved to be poor substrates. We devised a simple HPLC-based assay to identify Kvβ2 reaction products. Using this assay we showed, for the first time, that Kvβ2 can catalyze a slow aldehyde dismutation reaction using 4-nitrobenzaldehyde as substrate and have identified the products of this reaction. The ability of Kvβ2 to carry out both an aldehyde reduction and a dismutation reaction is discussed in the light of current thinking on the role of redox chemistry in channel modulation.
- Alka, Kumari,Ryan, Barry J.,Dolly, J. Oliver,Henehan, Gary T.M.
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experimental part
p. 2012 - 2018
(2011/12/22)
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- In vitro metabolism of aromatic nitriles
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Studies on the metabolic fate of aromatic nitriles, in contrast to their aliphatic counterparts, have been minimal and the subject of controversy. The in vitro metabolic fate of several aromatic nitriles with varying substituents was investigated by using rat liver subcellular fractions, with a particular emphasis on the nitrile moiety. Benzonitriles and 4-cyanophenols underwent oxidative metabolism to produce ring-hydroxylated metabolites. On the other hand, 2-cyanophenol was resistant to metabolism. o-Tolunitrile was metabolized and produced o-cyanobenzyl alcohol and phthalide. Phthalide, however, was chemically derived from o-cyanobenzyl alcohol, the initial metabolite. 4-Nitrobenzonitrile was resistant to oxidation on the ring, but was readily reduced to the corresponding amine metabolite under both aerobic and anaerobic conditions. Nitroxynil (3-iodo-4-hydroxy-5-nitrobenzonitrile) was metabolized to produce 3-iodo-4-hydroxy-5-nitrobenzamide and 3-iodo-4- hydroxy-5-nitrobenzoic acid. The enzyme(s) responsible for this hydrolytic metabolism was primarily localized in the cytosol. Among the nitriles tested, o-tolunitrile and nitroxynil produced metabolites in which the nitrile moiety was modified. Nitroxynil, however, was the only compound that was directly metabolized on the nitrile moiety by the rat liver enzyme(s).
- Markus,Kwon
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p. 1729 - 1734
(2007/10/02)
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