Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• an overall yield of 42% over five steps. One-pot deprotection–oxidation [14] of the oxazolidine moiety in 9 proceeded uneventfully to provide N-Boc-2-amino-6-heptenoic acid (10) in good yield. The latter was smothly protected as its methyl ester using methyl iodide in the presence of cesium carbonate

Synthesis of substituted Z-styrenes by Hiyama-type coupling of oxasilacycloalkenes: application to the synthesis of a 1-benzoxocane

• James R. Vyvyan,
• Courtney A. Engles,
• Scott L. Bray,
• Erik D. Wold,
• Christopher L. Porter and
• Mikhail O. Konev

Beilstein J. Org. Chem. 2017, 13, 2122–2127, doi:10.3762/bjoc.13.209

• on the intramolecular Buchwald–Hartwig etherification [38][39][40] of bromoalcohol 15 to prepare eight-membered cyclic ether 24 (Table 2). The use of Pd(II) catalyst precursors with BINAP ligands and carbonate bases in toluene [38][39] was ineffective, returning significant amounts of unreacted

Enzymatic separation of epimeric 4-C-hydroxymethylated furanosugars: Synthesis of bicyclic nucleosides

• Neha Rana,
• Manish Kumar,
• Vinod Khatri,
• Jyotirmoy Maity and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2017, 13, 2078–2086, doi:10.3762/bjoc.13.205

• . The reaction was quenched with a cold saturated aqueous solution of sodium hydrogen carbonate (200 mL) and the reaction mixture was extracted with chloroform (3 × 100 mL). The combined organic phase was washed with saturated aqueous solutions of NaHCO3 (2 × 100 mL), brine (2 × 100 mL) and cold water

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• other flexible linkers investigated are carbonate [57], as well as oxalic [57], malonic [53][57][58], and glutaric [59] dicarboxylic acids. However, like in the case of succinoyl linkers, higher flexibility led to more relaxed stereoselectivity. Further variations upon this method involved the

• a solid supported peptide sequence that was connected to the 6-hydroxy groups of the sugar units using carbonate linkages (Scheme 10) [79]. The hydroxyproline (Hyp, (2S,4R)-4-hydroxypyrrolidine-2-carboxylic acid) linked glycosyl donor and acceptor system failed to provide the product of the

One-pot multistep mechanochemical synthesis of fluorinated pyrazolones

• Joseph L. Howard,
• William Nicholson,
• Yerbol Sagatov and
• Duncan L. Browne

Beilstein J. Org. Chem. 2017, 13, 1950–1956, doi:10.3762/bjoc.13.189

• no further improvement (Table 2, entry 5). The fluorination reaction studied here proceeds via an enolate which is aromatic and therefore is relatively facile (compared to the fluorination of other heterocyclic systems). Introduction of a mild base, such as sodium carbonate to the reaction vessel

• within a two hour reaction time (Table 2, entry 8). Pleasingly a combination of sodium carbonate with the sodium chloride grinding auxiliary resulted in complete reaction after one hour (Table 2, entry 9). The only compatibility issue remaining was the acid present from the first step. However, as a base

• improved the reactivity of the fluorination, the final conditions make use of enough sodium carbonate both to neutralise the remaining acid and accelerate the second step. By applying these compatible conditions to the one-pot procedure, the desired fluorinated pyrazolone was isolated in 75% yield (Scheme

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• carbonate in dioxane as well as in DMAA (Table 1, entries 2–5). Unfortunately, in all cases the yields of the target sultam 10a were poorer. Since NaH in dioxane had given the best results, various parameters of these conditions were tested. With a reduced amount of NaH (2.5 instead of 4.0 equiv) the

• %. Alkylation of 11 with 4-methoxybenzyl chloride in DMF in the presence of potassium carbonate according to a previously published protocol [17] gave the N-PMB-protected tertiary sulfonamide 12 in 89% yield. The attempted palladium-catalyzed cyclization of 12 under the conditions employed above (Scheme 4), yet

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• ) technique for the synthesis of dialkyl carbonates [90]. Using potassium carbonate, alkyl halide and 2 equiv of phase-transfer catalyst 18-crown-6 yielded dialkyl carbonate in 74%. However, in absence of 18-crown-6 the yield was only 2% at 17 h (Scheme 20). Transesterification is a synthetic approach mostly

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

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

• can be regarded as synthetic equivalents of isothiocyanate reagents, they were utilized for the solid-state synthesis of thioureas by milling 26 with two equivalents of aniline in the presence of sodium carbonate as the base. After 10 minutes, symmetrical aromatic thioureas 28a–d were obtained in

• thiocarbamoyl substrate with a mixture of sodium carbonate and ammonium chloride. This mixture released ammonia gas during milling and allowed the amination reaction to take place under solvent-free mechanochemical conditions. Following a simple aqueous work-up and filtration, the desired primary thioureas 32

• potassium carbonate as the base was necessary to deprotonate the sulfonamide and thus increase its reactivity. After milling for 2 hours with the corresponding iso(thio)cyanate, the sulfonyl (thio)ureas 42a–c were isolated in excellent yields, for example the drug tolbutamide (1) in 92% (Scheme 17a

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

• /RGO-40 A mixture of aryl halide (1 mmol), thiol (1.2 mmol), potassium carbonate (1.2 mmol), Ni/RGO-40 catalyst (22 mg; Ni content is 8.8 mg, 0.15 mmol, 15 mol %) in DMF (3 mL) were taken in a 15 mL sealed tube, flashed and filled with N2 gas and quickly screw-capped. The reaction mixture was then

• under vacuum to obtain a free-flowing black powder. This material was used for the next catalytic cycle. Gram-scale procedure for C–S cross-coupling using Ni/RGO-40 A mixture of 4-iodoanisole (1 g, 4.27 mmol), thiophenol (0.563 g, 5.12 mmol), potassium carbonate (0.706 g, 5.12 mmol), Ni/RGO-40 catalyst

Mechanochemical N-alkylation of imides

• Anamarija Briš,
• Mateja Đud and
• Davor Margetić

Beilstein J. Org. Chem. 2017, 13, 1745–1752, doi:10.3762/bjoc.13.169

• addition of a small amount of solvent for LAG (liquid-assisted grinding) [27] was tested as well. The results are collected in Table 1. The best results were achieved by the use of K2CO3 as base, with large excess of dibromide and carbonate. Within one hour of milling, 1 was quantitatively converted to the

• with benzyl bromide with LAG (DMF) to obtain alkylated products in high yields. Formation of potassium salts of other imides listed in Table 3 by K2CO3 has been also proven by ex situ IR monitoring (see Supporting Information File 1). It indicates that potassium carbonate is capable of the

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• ingredients. Peng et al. reported a novel catalyst oxidant combo of ([Cu(MeCN)4]BF4) and tert-butylperoxy 2-ethylhexyl carbonate (TBPC) to generate the corresponding indoles 84 in excellent yields from indolines 83 (Scheme 30) [91]. The methodology was further utilized in the conversion of

• K-10 and Pd/C as catalysts. The microwave-assisted synthesis of β-carboline 96 from tetrahydro-β-carboline 95 using catalytic Pd/C and lithium carbonate at high temperature is also reported [96]. This high yielding procedure gets completed within a few minutes (Scheme 36). Although the reaction

• lithium carbonate at high temperature. 4-Methoxy-TEMPO-catalyzed aerobic oxidative synthesis of 2-substituted benzazoles. Plausible mechanism of the 4-methoxy-TEMPO-catalyzed transformation. One-pot synthesis of 2-arylquinazolines, catalyzed by 4-hydroxy-TEMPO. Oxidative dehydrogenation – a key step in

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• required functionalization of both amino groups present in 2-ABA was achieved by different routes involving selective N-acylation and cesium carbonate-mediated N-alkylation reactions, avoiding protection/deprotection steps. The heterocycles were efficiently synthesized in short reaction times by microwave

• , necessary for the synthesis of dihydroquinazolines 2, were prepared by N-alkylation of the arylamino group present in compounds 4 using alkyl halides. In a previous work [63], we developed a methodology for the selective N-alkylation of anilines with ω-halonitriles in the presence of cesium carbonate and

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• potassium carbonate led to the formation of anti-10e' as a sole product, presumably, via a base-promoted enolization and subsequent isomerization of the syn-10e (10e', Scheme 2). Enolization is thought to be a key event in the formation of the CCR products which can occur via two alternative mechanisms: (a

Total synthesis of elansolids B1 and B2

• Liang-Liang Wang and
• Andreas Kirschning

Beilstein J. Org. Chem. 2017, 13, 1280–1287, doi:10.3762/bjoc.13.124

• equiv) and boronate 13 (39.12 mg, 60.0 µmol, 1.5 equiv) in THF (5 mL) and H2O (1.25 mL) were sequentially added thallium(I) carbonate (33.92 mg, 72.0 µmol, 1.8 equiv) and Pd(PPh3)4 (13.93 mg, 12.0 µmol, 0.3 equiv) at room temperature. The reaction mixture was stirred for 4 h and then H2O was added. The

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• using ammonium carbonate (Table 1, entry 2) also ended up in a messy byproduct mixture and the poor isolated yield was also a consequence of the exhaustive chromatographic cleanup utilized. The most problematic issue was to avoid byproduct 6. Because of its similar adsorption characteristics to the

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

• Stephan Scheeff and
• Dirk Menche

Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108

• was oxidized in 2 steps with DMP and NaClO2/NaH2PO4 to the free acid 40. The high regioselectivity of the Alder-Ene reaction is remarkable and was argued to be derived by a coordinating effect of the carbonate. Also, the overall high yield for synthesis of this elaborate vinyl iodide is impressive

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• potassium carbonate in MeOH/H2O solution to give the ketone 15. Treatment of 15 with hydrazine monohydrate in methanol gave the expected product 16 in 57% yield (Scheme 3). The 1H NMR and 13C NMR spectra of these two compounds 13c and 16 were completely different from each other. The methylene protons in 16

Synthesis of D-manno-heptulose via a cascade aldol/hemiketalization reaction

• Yan Chen,
• Xiaoman Wang,
• Junchang Wang and
• You Yang

Beilstein J. Org. Chem. 2017, 13, 795–799, doi:10.3762/bjoc.13.79

• excellent yield (91%). Saponification of all esters in 16 with potassium carbonate followed by acidic cleavage of the isopropylidene acetal group with aqueous acetic acid furnished D-manno-heptulose (1, 76% over two steps). The structure of 1 was found to be in good agreement with those reported for α-D

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

• alternative to palladium, a 1 wt % platinum catalyst supported onto calcium carbonate was also reported, however, with no practical advantages over Pd in terms of partial hydrogenation (27% ene selectivity at 78% conversion and 373 K) [173]. Methyl phenylpropiolate and 4-phenyl-3-butyn-2-one The continuous

Conjecture and hypothesis: The importance of reality checks

• David Deamer

Beilstein J. Org. Chem. 2017, 13, 620–624, doi:10.3762/bjoc.13.60

• with mineral components of peridotite in the sea floor, a process called serpentinization. The reaction produces hydrogen and a strongly alkaline (pH 9–11) hot medium saturated with carbonate. When the warm fluid contacts cooler seawater, calcium carbonate and other minerals precipitate to form white

Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

• Jan Szabo,
• Julian Greiner and
• Gerhard Maas

Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57

• and 5 were found to react with acid chlorides 2 in two different ways (Scheme 3). When the acid chloride was added slowly to a solution of the guanidinium salt in chloroform in the presence of solid sodium carbonate, the expected N,N’,N’’-tris(acylamino)guanidines 6 were formed as the major products

• , method A; Table 1). With easily hydrolyzing 4-nitrobenzoyl chloride (2c), the alkaline medium had to be replaced by solid potassium carbonate, which resulted, however, in a separable mixture of 6c and 7c. It should be emphasized that, although the two procedures for the acylation of guanidinium salts 4

Brønsted acid-mediated cyclization–dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines

• Ramana Sreenivasa Rao and
• Chinnasamy Ramaraj Ramanathan

Beilstein J. Org. Chem. 2017, 13, 428–440, doi:10.3762/bjoc.13.46

• mL) was added phenylboronic acid (122 mg) and 2 M aqueous sodium carbonate (0.8 mL) under a nitrogen atmosphere. The reaction mixture was heated to 90 °C and stirred for 2 h. The reaction mixture was quenched with water and the mixture was extracted with ethyl acetate. The organic phase was separated

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

• the composition of the minerals themselves, rather than their being simply examples of large molecules associating nonspecifically with large surfaces. Using this approach, we have discovered Periodic Table trends in the binding of oligomeric RNA to alkaline earth carbonate minerals and alkaline earth

• sulfate minerals, where those trends are the same when measured in natural and synthetic minerals. They are also validated by comparison of co-precipitated synthetic minerals. We also show differential binding of RNA to polymorphic forms of calcium carbonate, and the stabilization of bound RNA on

• aragonite. These have relevance to the prebiotic stabilization of RNA, where such carbonate minerals are expected to have been abundant, as they appear to be today on Mars. Keywords: carbonates; natural minerals; origins of life; RNA adsorption; synthetic minerals; Introduction It has been nearly 70 years

Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

• Maximilian Maier,
• Magnus S. Schmidt,
• Markus Ringwald and
• Christoph P. Fik

Beilstein J. Org. Chem. 2017, 13, 372–383, doi:10.3762/bjoc.13.40

• stages, we decided to use a procedure which would allow the isolation of the free diamine. Therefore, we used a substantial excess of the alkylamine without any other/further solvent and potassium carbonate as scavenger base for the hydrobromide (leading to insoluble potassium bromide). After work-up, we

• ) were measured using an Anton Paar Abbemat 200 refractometer at 20 °C. General procedure for the synthesis of N,N’-diacyl-N,N’-dialkyl-1,4-diamines 1–6 Amination a) Synthesis of 1,4-but-2-enediamine: Potassium carbonate (2.5 equiv) was added to the alkylamine (15 equiv) and cooled to 0–5 °C. The