Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

• Ana Franco,
• Sudipta De,
• Alina M. Balu,
• Araceli Garcia and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1439–1445, doi:10.3762/bjoc.13.141

• decrease in the catalytic activity due to material deactivation. Conclusion A simple mechanochemical ball milling process was used to prepare highly active transition-metal-supported reduced graphene oxide catalysts. The catalysts were used to produce the highly useful aromatic compound vanillin, by

• (JEOL) and Phillips Analytical FEI Tecnai 30 microscopes. SEM micrographs were recorded on a JEOL-SEM JSM-6610 LV scanning electron microscope in backscattered electron model at 3/15 kV. DRIFT spectra were recorded on a PIKE Technologies MB 3000 ABB at room temperature. Catalytic activity tests In a

Synthesis of novel 13α-estrone derivatives by Sonogashira coupling as potential 17β-HSD1 inhibitors

• Ildikó Bacsa,
• Rebeka Jójárt,
• János Wölfling,
• Gyula Schneider,
• Bianka Edina Herman,
• Mihály Szécsi and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2017, 13, 1303–1309, doi:10.3762/bjoc.13.126

• semihydrogenation of different arylacetylenes using Pd(OAc)2 or Pd(PPh3)2Cl2 as the catalyst and DMF/KOH as a hydrogen source, under conventional heating [30]. The first catalyst afforded cis-alkenes in high yields with excellent chemo- and stereoselectivity. The latter catalyst displayed lower catalytic activity

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• . As the prepared porous polymer SugPOP-1 is based on hemiacetal glucose, Ag nanoparticles (AgNPs) can be successfully incorporated into the polymer by an in situ chemical reduction of freshly prepared Tollens’ reagent. The obtained AgNPs/SugPOP-1 composite demonstrates good catalytic activity in the

• good catalytic activity, which takes on important implications for the conversion of nitro compound precursors or intermediates to the corresponding amino or amine compounds in the preparation of pharmaceuticals and agrochemicals [42][43]. 4-Nitrophenol (4-NP) can cause water pollution, which has

• aroused widespread concern, while its reduced product, 4-aminophenol (4-AP), is an industrial intermediate for uses such as anticorrosion lubricants and analgesic and antipyretic drugs [44]. The catalytic activity of the AgNPs/SugPOP-1 composite was tested by the reduction of 4-NP at room temperature with

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• was found from in vitro evolution experiments that the introduction of G∙U base pairs close to the site of ligation leads to enhanced cross-catalytic activity. Figure 8b shows the sequence and secondary structure of the A∙B∙E’ complex. The site of ligation is indicated by the curved arrow and the G∙U

• pairs that are depicted in a solid box induce a wobble in the sequence that results in the enhanced catalytic activity. When this wobble is installed in both enzymes of the cross-catalytic set, exponential growth of the system can be achieved over multiple cycles. With an exponential replicator in hand

• E1 to E12 and are shown in Figure 8c. It is important to note that mutations between enzymes are such that the stability of the ligase duplex due to base pairing is not altered, but only the catalytic activity and replication rate are affected. All these enzymes were shown to cross-replicate, with

From chemical metabolism to life: the origin of the genetic coding process

• Antoine Danchin

Beilstein J. Org. Chem. 2017, 13, 1119–1135, doi:10.3762/bjoc.13.111

• ” templates of RNA sequences matching the peptide sequence via a coding process, asked for the synthesis of their exact copies, i.e., replication. This operation evolved from natural RNA catalytic activity [62] and progressively improved its autocatalytic reproduction by using increasingly more accurate

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• adsorption on the atomically dispersed Pd sites. Electrostatic stabilization of Pd atoms was ascribed to a strong interaction with the nitrogen-coordinating species on the basis of DFT calculations. Effective stabilization also prevented site aggregation, resulting in pretty constant catalytic activity over

• (13 s), that suggests a high contribution to catalytic activity by easy accessible PdNP. No catalyst efficiency decay was observed over 6 h time-on-stream. Worse performances were shown by other Pd packed-bed catalysts using conventional support materials, including mesoporous titania powder

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• phenols in water at room temperature. This catalyst can be reused many times without loss of the catalytic activity. Moreover, this catalyst could also be applied in the synthesis of anilines. 1.1.2 Copper-catalyzed hydroxylation of aryl halides: Copper catalysts are considered as economical and stable

• catalysts. However, copper catalysts often have a low catalytic activity to activate the C–Hal bond. Fortunately, along with the development of various bidentate ligands, the copper-catalyzed C–O coupling reaction has been extensively applied in the synthesis of phenols from aryl halides. However, the

• catalyst and KOH as base [42]. In 2011, the Jiang group employed 8-hydroxyquinoline-N-oxide (L10) as ligand and hydroxylation occurred in the presence of CuI as catalyst and CsOH as base (Scheme 19) [43]. The catalytic activity of the reaction system depended on the reaction temperature. The reactions of

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• batch mode [61]. Pericàs and co-workers taking advantage of the high catalytic activity, robustness and recyclability of the supported catalyst, performed also straightforward gram synthesis of target compounds. In the context of photocatalysis and oxidations using flow microreactors [62][63], Noël

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• obtain 1-indanones in good yields. Moreover, the metal triflate could be recovered and reused without loss of catalytic activity. Indatraline that blocks the action of cocaine contains moieties having antidepressant, antihistamine and blood pressure-lowering properties. Yun et al. [23] have developed a

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• . Adsorption of these onto mineral surfaces has been shown to slow that destruction [9], in some cases without greatly damaging the catalytic activity of those pre-biopolymers [10], in other cases with evolution [11]. As Hazen and Sverjensky remark [12], mineral environments are far more complex than the

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

• Yi Lai,
• Zhijian Zong,
• Yujie Tang,
• Weimin Mo,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen,
• Liqun Jin,
• Wen-hua Sun and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 213–221, doi:10.3762/bjoc.13.24

• up to 325 °C. With these sterically hindered iminopyridine–palladium complexes Pd1 to Pd5 in hand, we firstly investigated their catalytic activity directly in Suzuki cross-coupling reactions with chlorobenzene as the electrophile. The reactions were performed under the previously reported conditions

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• acidity or basicity. In fact, it was shown that the pKa of organic acids and bases often shifts by orders of magnitude upon association with CB[n] [16][17][18][19][20][21][22][23][24], which may be used, e.g., to modify catalytic activity [6] or for sensing purposes [7]. Notably, the same effect was

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• catalytic activity. The aggregation is a slow process in distilled water, but happens instantly in the presence of salts, e.g., in tap water, surface waters and waste waters. β-CD can be used for stabilization of colloidal TiO2 systems [33] – at least in distilled water – as it is adsorbed on the surface of

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• one of the first examples of utilizing tetralkylammonium salts as hydrogen bond donor catalysts, the authors provided no mechanistic proposal for the catalytic activity of L7–L10, and the activation of the imine by the formation of a C–H···N hydrogen bond was proposed later by Maruoka and Shirakawa

• catalyst with X = I, and R = Oct promoted the reaction between 1-chloroisochroman and silyl enol ether at 0.5 mol % catalyst loadings (70% yield, 6 h). A good correlation was observed between the catalytic activity and halogen affinity, and the Ka of L22 with X = I, R = Oct with bromide anion was

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

• Anna Zaghi,
• Daniele Ragno,
• Graziano Di Carmine,
• Carmela De Risi,
• Olga Bortolini,
• Pier Paolo Giovannini,
• Giancarlo Fantin and
• Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

• 150 h. After the achievement of the steady-state regime (ca. 3 h), an almost full conversion of 1a (>95%) was maintained for ca. 120 h, while a progressive loss of catalytic activity was observed after that time. Continuous-flow Stetter-like reactions (Table 5) Microreactor R5 was fed with a DMF

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• high yields. For these reactions, which required a higher operating temperature than before (110 °C compared to 80 °C), polymethylhydrosiloxane was used as the reductant, and 14 could be recovered and reused efficiently in numerous reaction cycles without loss of catalytic activity. At about the time

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

• Ángel Cantín,
• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

• biofuels [34], it is important to get insight into the lack of catalytic activity of Beta for the retro-DAR, and elucidate whether this is a general effect with zeolites. Due to the diffusion limitations with Beta we have selected two extra-large pore zeolites, SSZ-53 (BET surface area = 377 m2/g) and SSZ

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

• Raimondo Maggi,
• N. Raveendran Shiju,
• Veronica Santacroce,
• Giovanni Maestri,
• Franca Bigi and
• Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

• of levulinic acid were stirred at 100 °C in a sealed tube for 2 h under air in the presence of the amount of a solid catalyst necessary to have 1 mol % of acid sites. The results are reported in Table 1. All of the prepared silica-supported sulfonic acids showed very good catalytic activity for the

Chiral ammonium betaine-catalyzed asymmetric Mannich-type reaction of oxindoles

• Masahiro Torii,
• Kohsuke Kato,
• Daisuke Uraguchi and
• Takashi Ooi

Beilstein J. Org. Chem. 2016, 12, 2099–2103, doi:10.3762/bjoc.12.199

• extended steric hindrance over the catalytically active sites, eroded the catalytic activity and diastereocontrol (Table 1, entry 6). These observations demonstrated the superior capability of 1c in facilitating this stereoselective Mannich-type transformation, for which the loading was reduced to 1 mol

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• including acetic, succinic, benzoic, and methacrylic acid and alcohols such as linear, branched and cyclic C1–C6 compounds. The PIL could be reused up to five times without any loss of catalytic activity and yields of various esters were always nearly quantitative. Applications of ILs: Organocatalysts find

• be recovered and reused to allow quantitative conversions even after several recycles. Moreover, the study highlighted that the catalytic activity increased with increasing acidity of the ILs and particularly with cations bearing SO3H anions (Scheme 5: ILs I, II, III, and IV). The same imidazolium

• of dimethyl carbonate with n-butanol has been accomplished using tetraethylammonium-based amino acid ionic liquids ([N2222][AA]) as homogeneous catalysts (Figure 3) [68]. [N2222][Pro] exhibited the best catalytic activity yielding an overall 72% yield of the dibutyl carbonate (DBC) product. Quantum

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• ]. The Baeyer–Villiger oxidation of ketones 76 under the action of oxygen to the related esters 77 was performed using metal-free carbon (Ketjen Black) as a solid catalyst and benzaldehyde as the sacrificing agent. This metal-free carbon catalyst showed excellent catalytic activity and can be recycled

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• . Results and Discussion We herein report the synthesis of an ethylene-linked bisthiazol-2-ylidene dicopper(I) complex 2 that features high catalytic activity in CuAAC reactions. The advantage of this new complex 2 in comparison to dicopper complexes previously described by our research group [40] is its

• dichloromethane at room temperature was used (Table 1 and Figure 2). Due to the highly exothermic nature of the triazole formation, a high dilution of the reaction mixture and low catalyst loadings are necessary to prevent a thermal runaway. In order to compare the catalytic activity of complex 2 with

• ], while CuOAc excels in heterogeneous catalysis and in cost-effectiveness [38]. The reaction with ethyl propiolate in the presence of 0.9 mol % catalyst is very slow with a half conversion time of more than nine hours (Table 1, entry 4, yellow diamonds). We attribute this poor catalytic activity to the

Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

• Stefan Mark,
• Hubert Wadepohl and
• Markus Enders

Beilstein J. Org. Chem. 2016, 12, 1372–1379, doi:10.3762/bjoc.12.131

• polymerization. All complexes investigated show very high catalytic activity and the additional side arm minimizes chain-transfer reactions, leading to increase of molecular weights of the resulting polymers. Keywords: chromium single-site catalysts; olefin polymerization; ultra-high molecular weight

• produce without lowering their very high catalytic activity. Solid-state molecular structures of selected complexes 4, 7 and 8 (left, middle and right, respectively). Probability level: 50%. Hydrogen atoms and carbon labels are omitted for clarity. a) Calculated structures of cationic chromium complexes

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• the enantioselectivity and catalytic activity of the corresponding iridium complexes. Initial attempts to introduce a silyl or acetyl group by deprotonation with potassium hydride and subsequent reaction with silyl triflates or acetyl chloride failed. The NeoPHOX ligand 14 showed no reaction under

• oxazoline ring. Apparently, a polar potentially coordinating substituent near the metal center reduces or can even completely inhibit catalytic activity. The deactivating effect of a coordinating oxygen function could also explain the different conversions observed with the silyl ether-bearing catalysts

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• ’-position of the BINOL backbone had a remarkable effect on the catalytic activity and enantioselectivity. Based on this method, the authors also achieved the synthesis of a key intermediate efficiently (99% yield and 93% ee), which had been used in the total synthesis of (+)-folicanthine [68]. The Zhang

• completely inhibited the catalytic activity. Interestingly, the authors found that the yields and enantioselectivities dramatically decreased