Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• impedes the use of most organic solvents, while the gaseous nature of methane makes it impossible to form a homogenous reaction system without a solvent. Pérez and co-workers addressed this problem by using supercritical carbon dioxide (scCO2) as the reaction medium. Methane can be dissolved in scCO2

• functionalization of the primary sites was observed in the presence of Tp(CF3)2,BrCu(MeCN); while hexane and scCO2 made little difference as compared to Tp(CF3)2,BrAg(thf) catalyzed reactions. These results may be related to the interaction of the ligand with carbon dioxide. A net electron density flux from the

• metal center to the ligand and to carbon dioxide was supported by experimental data and DFT studies. Such interaction increases the electrophilicity of the carbene moiety and thus lowers the activation energy for C–H bond insertion. Other ligands have also been explored for the metal–carbene C(sp3)–H

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• McDermott et al. in 2008 (Figure 6) [41]. In two steps (asymmetric deprotonation followed by a carbon dioxide quench and coupling with N-benzylpiperazine, 22) product 23 was produced in 48% yield with 89:11 enantioselectivity favoring the R-configuration of the newly generated carbon center. In contrast to

Highly stable and reusable immobilized formate dehydrogenases: Promising biocatalysts for in situ regeneration of NADH

• Barış Binay,
• Dilek Alagöz,
• Deniz Yildirim,
• Ayhan Çelik and
• S. Seyhan Tükel

Beilstein J. Org. Chem. 2016, 12, 271–277, doi:10.3762/bjoc.12.29

• decrease operational costs. NAD+-dependent formate dehydrogenase (FDH, EC 1.2.1.2) catalyzes oxidation of formate to carbon dioxide (CO2) [6]. FDH is industrially used as coenzyme for the regeneration of NADH [7][8], as sensor for the determination of formic acid [9], and as catalyst for the production of

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• hemiaminals derived from fluoral (CF3C(OSiMe3)NR2), can generate CnF2n+1Cu via carbon–carbon bond cleavage. Herein we focus on Cu-mediated perfluoroalkylation reactions through which carbon dioxide, the esters, or the N-formylamines are eliminated from the perfluoroalkyl reagents. Review Decarboxylation of

Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

• Stefan Naumann,
• Johannes Klein,
• Dongren Wang and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 2261–2266, doi:10.3762/bjoc.11.246

• -handle metal-free process which is more competitive in comparison with other catalytic systems can be realized [26]. Results and Discussion Several five-, six- and seven-membered NHCs were prepared and reacted with carbon dioxide to receive the corresponding CO2 adducts (Scheme 1, top), following

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium–salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the

• catalysts induced the formation of cyclic carbonates under mild reaction conditions (25–35 °C; 1–10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction

• mixture and reused. Keywords: aluminium; carbon dioxide; cyclic carbonate; epoxide; salen; Introduction Carbon dioxide is a renewable and inexpensive carbon source, so great efforts have been directed at developing novel methods for the valorization of this abundant raw material [1]. One way of

Surprisingly facile CO₂ insertion into cobalt alkoxide bonds: A theoretical investigation

• Willem K. Offermans,
• Claudia Bizzarri,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 1340–1351, doi:10.3762/bjoc.11.144

• Abstract Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory

• , a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy. Keywords: activation; alkoxide; carbon dioxide; cobalt; insertion; salen; Introduction Carbon dioxide (CO2) has been known to be an attractive carbon source for decades [1][2][3][4][5][6

• be very beneficial to harness a part of this stream for producing valuable products [7]. From a thermodynamic point of view, however, CO2 is highly stable and, thus, shows low reactivity. One way to overcome this thermodynamic hurdle is to react carbon dioxide with relatively high-energy molecules

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• intermediate passes into a tube-in-tube reactor, where carboxylation takes place furnishing the lithium carboxylate 129. Excess carbon dioxide is subsequently removed using a degassing tube before reacting species 129 with a further stream of n-BuLi to induce cyclisation to dibenzosuberone (130) in a short

Azobenzene-based inhibitors of human carbonic anhydrase II

• Leander Simon Runtsch,
• David Michael Barber,
• Peter Mayer,
• Michael Groll,
• Dirk Trauner and
• Johannes Broichhagen

Beilstein J. Org. Chem. 2015, 11, 1129–1135, doi:10.3762/bjoc.11.127

• kinetics. Keywords: azobenzene chemistry; enzyme inhibitors; human carbonic anhydrase II; sulfonamide; X-ray crystallography; Introduction Carbonic anhydrase (CA) is an ubiquitously found zinc-containing metalloenzyme with many isoforms, which all catalyze the conversion of carbon dioxide and water to

• hCAII. a) hCAII (pdb: 2vva [7]) catalyzes the hydration of carbon dioxide to bicarbonate and a proton (left) as well as the hydrolysis of pNPA to acetate and a colored phenolate (λmax = 400 nm). b) Aryl sulfonamide-containing pharmacophores of hCAII. c) Aryl sulfonamide merged to azobenzenes. Crystal

DBU-promoted carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone

• Wen-Zhen Zhang,
• Si Liu and
• Xiao-Bing Lu

Beilstein J. Org. Chem. 2015, 11, 906–912, doi:10.3762/bjoc.11.102

• Wen-Zhen Zhang Si Liu Xiao-Bing Lu State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116024, P. R. China 10.3762/bjoc.11.102 Abstract The carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone with carbon dioxide promoted by the organic base 1,8

• -diazabicycloundec-7-ene (DBU) is reported. This reaction provides convenient access to the biologically important compounds 4-hydroxy-2H-chromen-2-one and 4-hydroxy-2(1H)-quinolinone in moderate to good yields using carbon dioxide as the carboxylation reagent. An acyl migration from nitrogen to carbon is observed

• in the reaction of o-acetamidoacetophenone. Keywords: acyl migration; carbon dioxide; carboxylation; cyclization; condensation; Introduction 4-Hydroxy-2H-chromen-2-ones and 4-hydroxy-2(1H)-quinolinones are key structural subunits found in many natural products [1], commercial drugs [2][3] and

CO₂ Chemistry

• Thomas E. Müller and
• Walter Leitner

Beilstein J. Org. Chem. 2015, 11, 675–677, doi:10.3762/bjoc.11.76

• will continue to be carbon-based. One of the most abundant renewable resources of carbon is carbon dioxide (Figure 1). Carbon capture technologies are being implemented [1] to capture a part of the yearly anthropogenic CO2 emission of 36,600 million metric tons of CO2 [2]. If only a fraction of the

• use of carbon dioxide as chemical feedstock. Notably, the use of CO2 for manufacturing materials and chemicals is still in its infancy. Carbon dioxide (CO2) has long stirred the fascination of chemists. A rich chemistry has evolved utilizing this molecule in chemical synthesis [4]. Hitherto the low

• reactivity of the CO2 molecule poses significant challenges to the utilization of carbon dioxide in industrial applications. Thus, the CO2 molecule is commonly perceived to be highly inert. This perception clearly stems from the high chemical stability of carbon dioxide. However, the reactivity of the CO2

Anion effect controlling the selectivity in the zinc-catalysed copolymerisation of CO₂ and cyclohexene oxide

• Sait Elmas,
• Muhammad Afzal Subhani,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 42–49, doi:10.3762/bjoc.11.7

• copolymerisation reaction. Keywords: anion effect; carbon dioxide; CO2 chemistry; copolymerisation; polyethercarbonate; zinc catalyst; Introduction The fixation of carbon dioxide (CO2) into polymers [1][2][3] provides highly promising options for the utilization of CO2 [4][5][6][7]. The copolymerisation of CO2

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• aminomethyl group. The C=O signal position is given as reference to show the absence of respective groups. The peaks marked with an arrow (CO2*) at 2200–2300 cm−1 are due to carbon dioxide from ambient air. FTIR spectra (left) of compounds 2 (a), 9 (b), 10 (c) and 11 (d). The formation of the sulfone groups

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• synthesis of chiral organic compounds [2][3]. Currently, the enzymatic reduction of carbon dioxide is under investigation as a possible route for fuel production [4]. A specific application, which leads to the production of methanol, occurs in water through three 2e– steps based on the use of three enzymes

• +, resulting in NADH generation, which can be further used in enzymatic processes including carbon dioxide reduction. The product of glycerol oxidation is 1,3-dihydroxyacetone. This species is not very stable and can be converted into other monomeric or polymeric species. Oxidation of glycerol is still under

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• of carboxylic acids from carbon dioxide. An overview is given of different substrate groups which form carboxylic acids upon CO2 fixation, including mechanistic considerations. While most work focuses on the electrocarboxylation of substrates with sacrificial anodes, this review considers the

• possibilities and challenges of implementing other synthetic methodologies. In view of potential industrial application, the choice of reactor setup, electrode type and reaction pathway has a large influence on the sustainability and efficiency of the process. Keywords: carbon dioxide; carboxylic acids

• ; counter electrode reaction; electrocarboxylation mechanism; reactor setup; Introduction Carbon dioxide recycling Implementing sustainable, resource-efficient chemical processes to meet the world’s growing demand for energy and chemicals is one of today’s major challenges. Depletion of fossil resources

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• Modified Eagle’s Medium (DMEM) supplemented with 5% FBS, 100 units mL–1 penicillin and 100 μg mL–1 streptomycin. All cells were incubated in a 5% carbon dioxide, water saturated incubator at 37 °C. Fluorescence microscopy with Tz–biotin 10. HEK 293T cells (22,000 cells/cm2) were seeded in 4-well ibiTreat μ

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• Jocelyn Peach Julian Eastoe School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K. 10.3762/bjoc.10.196 Abstract Supercritical carbon dioxide (scCO2) could be one aspect of a significant and necessary movement towards green chemistry, being a potential replacement for

• volatile organic compounds (VOCs). Unfortunately, carbon dioxide has a notoriously poor solubilising power and is famously difficult to handle. This review examines attempts and breakthroughs in enhancing the physicochemical properties of carbon dioxide, focusing primarily on factors that impact solubility

• and production of toxic reagents and products, avoidance of auxiliary substances where possible, and minimization of the energy requirements needed for the process, under this umbrella [2]. Attention has been drawn to the potential surrounding by the use of supercritical fluids and carbon dioxide in

Comparing kinetic profiles between bifunctional and binary type of Zn(salen)-based catalysts for organic carbonate formation

• Carmen Martín and
• Arjan W. Kleij

Beilstein J. Org. Chem. 2014, 10, 1817–1825, doi:10.3762/bjoc.10.191

• opposed to the binary catalyst that is connected with a first-order dependence on the catalyst concentration and a monometallic mechanism. Keywords: CO2 chemistry; cyclic carbonates; kinetic studies; salen complexes; zinc; Introduction Carbon dioxide may be regarded as an ideal, renewable carbon feed

• Scheme 2 first the epoxide coordinates to the Zn center allowing Lewis acid activation following the ring opening by nucleophilic attack of X. Then, carbon dioxide insertion into the metal–oxygen bond takes place and a consecutive cyclisation step (ring closure) occurs to give the cyclic carbonate and

• the Lewis acid ion thereby creating a higher degree of synergy. Experimental General procedures Carbon dioxide was purchased from PRAXAIR and used without further purification. Epoxide substrate and tetrabutylammonium iodide are commercially available and were used as received. Complexes 1 [51] and 2

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts

• Jong Yeob Jeon,
• Seong Chan Eo,
• Jobi Kodiyan Varghese and
• Bun Yeoul Lee

Beilstein J. Org. Chem. 2014, 10, 1787–1795, doi:10.3762/bjoc.10.187

• -transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C). Keywords: carbon dioxide; CO2 chemistry; cobalt complex; phthalic anhydride; propylene oxide; terpolymerization; Introduction Carbon dioxide (CO2) can be utilized to prepare aliphatic polycarbonates through coupling reactions

Syntheses of fluorooxindole and 2-fluoro-2-arylacetic acid derivatives from diethyl 2-fluoromalonate ester

• Antal Harsanyi,
• Graham Sandford,
• Dmitri S. Yufit and
• Judith A.K. Howard

Beilstein J. Org. Chem. 2014, 10, 1213–1219, doi:10.3762/bjoc.10.119

• derivative 5, after evaporation of toluene and purification by column chromatography in 61% yield. The two consecutive decarboxylation reactions reflect the greater stability of the benzylic carbanion formed on loss of carbon dioxide from this system (Scheme 2). With the series of 2-fluorophenylacetic acids

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• arylacetylenes 87, carbon dioxide and 3-bromo-1-aryl-1-propynes 88 (Scheme 40) [104]. In the reaction sequence a 1,6-diyne was generated in situ and cyclized to afford the two possible regioisomeric compounds. The level of regioselectivity can be enhanced by the tuning of electronic properties of the reactant

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• carbon dioxide [74][75] resulted in the formation of carboxylic acid 75. Birch reduction with concomitant methylation [76][77] followed by selective hydrogenation and reduction of the carboxylic acid resulted in the formation of alcohol 76. Installation of the remaining quarternary carbon center was

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

• Phei Li Lau,
• Ray W. K. Allen and
• Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

• , 43500 Semenyih, Selangor Darul Shsan, Malaysia 10.3762/bjoc.9.325 Abstract The palladium metal catalysed Heck reaction of 4-iodoanisole with styrene or methyl acrylate has been studied in a continuous plug flow reactor (PFR) using supercritical carbon dioxide (scCO2) as the solvent, with THF and

• ; flow chemistry; Heck; palladium; supercritical carbon dioxide; Introduction The use of cross-coupling reactions between organometallic reagents and organic halides as a straightforward method of carbon–carbon bond formation has gained much popularity over the past three decades. The development of

• the more reactive nature of the methyl acrylate as a substrate. Indeed the methyl acrylate is almost four times more reactive than styrene under identical conditions of temperature and pressure. Conclusion Supercritical carbon dioxide (scCO2) can be effectively used as a reaction solvent for the

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• radical to the double bond. The CF3-substituted alkene is finally obtained after elimination of carbon dioxide and Cu(I) (Figure 13). 3.3 Catalysis by other metals than Pd and Cu 3.3.1 Ru-catalyzed perfluoroalkylation of Csp2–H bonds. More than two decades ago, the group of N. Kamigata pursued extensive

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• by carbon dioxide (CO2), which is nontoxic, abundant, and economical, is the main advantage of this reaction. The mechanism of this transformation passes through iminophosphoranes that are versatile intermediates and can react with CO2 to generate isocyanates [20]. This reaction is compatible with a