Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• next screened as catalysts in Morita–Baylis–Hillman reaction, and their performance matched the previously published catalytic activity. An analogous click-type reaction between 4-nitrophenyl isothiocyanate and trans-1,2-diaminocyclohexane quantitatively afforded enantiomeric (1R,2R)-10 and (1S,2S)-10

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the

• times for the same reaction examined consecutively without any significant drop in catalytic activity. Figure 1 shows the results of consecutive recycle runs. Characterization of the recovered catalyst To establish the reaction mechanism, we characterized the recovered catalyst by Raman, XRD, XPS and

Selective enzymatic esterification of lignin model compounds in the ball mill

• Ulla Weißbach,
• Saumya Dabral,
• Laure Konnert,
• Carsten Bolm and
• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1788–1795, doi:10.3762/bjoc.13.173

• milling, reaction time and additives was also investigated (Table S1 in Supporting Information File 1). In addition to this, the catalytic activity of a number of other lipases was studied (Table 1). Amongst the commercially available lipases, CALA (lipase A from Candida antarctica, immobilized on

• β-nitro alcohols [32], and proved to be stable under ball milling conditions [10] exhibited lower catalytic activity than CALB (Table 1, entry 3). However, in both cases the alternative biocatalysts also afforded the monoacetylated dilignol derivative erythro-3a. Finally, lipase A showed no

• , milling frequency, presence of additives and different acyl donors were studied in detail. Amongst the various biocatalysts tested, the lipase CALB proved superior in terms of catalytic activity and stability in the ball mill. The high catalytic activity of the enzyme facilitated the monoacetylation of β

18-Hydroxydolabella-3,7-diene synthase – a diterpene synthase from Chitinophaga pinensis

• Jeroen S. Dickschat,
• Jan Rinkel,
• Patrick Rabe,
• Arman Beyraghdar Kashkooli and
• Harro J. Bouwmeester

Beilstein J. Org. Chem. 2017, 13, 1770–1780, doi:10.3762/bjoc.13.171

• test the catalytic activity of HdS in planta, its corresponding gene was transiently expressed in N. benthamiana. Since we have shown before that the mitochondria are a suitable subcellular compartment for the heterologous production of terpenes [26], and it is known that one of the multiple GGPP

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• materials via a simple method. Their corresponding water soluble Pd–NHC catalysts, in situ generated from the imidazolium salts L1–L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki–Heck reactions. The kinetic study revealed that the Pd catalyst derived from the imidazolium

• salt L1, bearing a pyridine-2-methyl substituent at the N3 atom of the imidazole ring, showed the best catalytic activity. Under the optimal conditions, a wide range of substituted alkenes were achieved in good to excellent yields from various aryl bromides and alkenes with the catalyst TON of up to

• presence of 0.01 mol % of Na2PdCl4/L and 2.0 equivalents of NaOEt at 100 °C in water and all the three reactions preceded for 24 h. As shown in Figure 2, the reaction using Na2PdCl4/L1 as the catalyst had a relatively shorter induction period and a higher catalytic activity than those of Na2PdCl4/L2 and

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• significant catalytic activity (yield = 38%). Finally, to test the scalability of the process, a set of reactions was carried out increasing the amount of substrate rac-1a under the optimized reaction parameters. (Table 4). Relative to the results obtained with 1 equivalent of rac-1a in the presence of LAG

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• relatively easy to prepare and can be obtained in different size and morphology by essentially controlling the synthetic method and experimental conditions. As a result of the excellent catalytic activity of NPs, they can be used under mild and, in some cases, in environmental sustainable conditions. In

• H2PdCl4 in the presence of poly(N-vinylpirrolidone) (PVP) [46][47]. These Pd NPs exhibited highly efficient catalytic activity in Suzuki–Miyaura coupling reactions [46][47] and nitroaromatic hydrogenations [48] in aqueous medium. Outstanding performance of these PVP-Pd NPs in the coupling reaction was

• )). In a first approach, time optimization was performed by using K2CO3 as base, at 130 °C by MW irradiation (entries 1–3, Table 1). The highest catalytic activity of PVP-Pd NPs was obtained after 10 minutes, when the yield of stilbene 3 achieved 100% (entry 3, Table 1). Reducing the catalyst loading

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• easily recovered and reused for at least five times without significant loss of catalytic activity. Keywords: ball milling; Heck reaction; layer double hydroxides; solvent-free; supported Pd catalyst; Introduction High-speed ball milling (HSBM)-assisted transition metal-catalyzed cross-coupling reactions

• catalytic activity in coupling reactions than that on acidic-supported materials. In the present work, co-precipitation was used for fabricating MgAl-LDHs with nitrate anions, followed by introducing disodium tetrachloropalladate (Na2PdCl4) into the LDH interlayer by the ion exchange method. The prepared

• at least five times efficiently without significant loss in catalytic activity, resulting in almost no change in the yields. Hence, the reusability of Pd/MgAl-LDHs is one of the major advantages for Heck reactions under HSBM conditions. Conclusion In summary, a supported and recyclable Pd catalyst (Pd

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• characteristics of various biomolecules, e.g., the catalytic activity of RNAs and their evolution potential [9][10][11], as well as processes that were essential for their syntheses, such as Fischer–Tropsch-like reactions [12], non-enzymatic RNA [13] or peptide polymerization [14]. Moreover, it has also allowed

• of RNAs for catalytic activity, which often requires the presence of high ion concentrations that are disruptive for the formation of primitive membrane models. Membranes composed of putatively prebiotic amphiphiles, such as single hydrocarbon chain species [20][21] may have been exemplars of such

• permeability of simple membranes was sufficient to permit an internalized synthetic or catalytic activity albeit at low yield and rate levels. However, both highlighted a different aspect of the compartmentalization: The use of aqueous metal ions could jeopardize the integrity of the compartment [20], and the

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