Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• tetrahydrofuran (THF) to obtain the N-Boc-serine methyl ester (5) in 93% yield [42]. Afterwards, the protected methyl ester 5 was subjected to iodination in the presence of iodine (I2), triphenylphosphane (PPh3) and imidazole in CH2Cl2 at 0 °C to deliver the iodo derivative 6 in 63% yield [43][44]. Finally, the

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• this reaction (Table 1, entries 10 and 11). Furthermore, different solvents were then tested, including MeCN, toluene, 1,4-dioxane, tetrahydrofuran (THF), and dimethylacetamide (DMAC), and we found the yield of y-1 was inferior to that done by DMF (Table 1, entries 12–16). With the optimum reaction

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• 16. A second [2 + 3] cycloaddition-based approach is described in Scheme 4. It started with the preparation of the methylene-bearing dipolarophile 25 from propargylamide 24 using gold(I) chemistry, which turned out to be tolerant to a wide variety of dry solvents (dichloromethane, tetrahydrofuran

Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus

• Jakob Bouton,
• Kristof Van Hecke,
• Reuven Rasooly and
• Serge Van Calenbergh

Beilstein J. Org. Chem. 2018, 14, 2822–2828, doi:10.3762/bjoc.14.260

• optimal side chain substituents are an o-chlorobenzamide on the 5-position and a non-substituted benzamide on the 2’-position. In absence of any structural information of the inhibitor–target interaction, we were interested in replacing the core tetrahydrofuran scaffold by a pyrrolidine ring in order to

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• precursor 16 was reduced using a borane tetrahydrofuran complex and immediately reacted in the Baeyer–Mills reaction without further purification. In Table 2 the yields using the Baeyer–Mills reaction are compared with the yields using the reductive azo condensation with lead [17]. Compared to the reductive

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• special safety precautions. Results and Discussion The anhydrides 9a–h were readily accessible by treatment of anthranilic acids AA with one equivalent of triphosgene in refluxing tetrahydrofuran at 0.36 molar concentration (Scheme 3). This procedure is an alternative to the existing published protocol

• ]oxazine-2,4(1H)-dione (9b). A 500 mL single neck round-bottomed flask equipped with a football-shaped PTFE stirring bar (16 mm × 37 mm) was charged with 2-amino-5-bromobenzoic acid (10.0 g, 46.3 mmol, 1.0 equiv) followed by the addition of tetrahydrofuran (230 mL, 0.2 molar) and solid triphosgene (13.7 g

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• with CH2- and O-bridges in their structure, diazoindandione 1f, diazocyclopentenedione 1g, and as a С–Н donor tetrahydrofuran was employed in the study (Figure 1). To determine the most efficient conditions for this reaction with diazodiketones 1, three sensitizers, acetophenone, benzophenone, and

• other hand, the sensitized photoexcitation of diazodiketones 1 gives rise to generation of triplet excited states of diazo compounds 3(1)1 which interact with the H-donor (tetrahydrofuran) producing N-alkyl-substituted hydrazones 2 (Scheme 2, reaction II). Based on the comparison study of the

• workup procedure hydrazone 2a and unreacted diazoketone 1a were isolated. 2-(2-(Tetrahydrofuran-2-yl)hydrazono)cyclopentane-1,3-dione (2a). Yield 168 mg (42%, calculated on the reacted diazodiketone 1a), bright-yellow oil; 1H NMR (400 MHz, CDCl3, δ) 12.93 (s, 1H), 5.61–5.53 (m, 1H), 4.08–3.99 (m, 1H

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• , chloroform, tetrahydrofuran, xylene, toluene, benzene, and chlorobenzene, whereas it was insoluble in water even after heating. In contrast, gel materials that did not flow upon inversion of the vial upside-down were obtained in 12 solvents with critical gelation concentration (CGC) values ranging from 16

Cationic cobalt-catalyzed [1,3]-rearrangement of N-alkoxycarbonyloxyanilines

• Itaru Nakamura,
• Mao Owada,
• Takeru Jo and
• Masahiro Terada

Beilstein J. Org. Chem. 2018, 14, 1972–1979, doi:10.3762/bjoc.14.172

• solvents, such as CHCl3, CH2Cl2, and PhCl, ethereal solvent, such as Et2O and tert-butyl methyl ether (MTBE), and toluene were less efficient (Table 2, entries 2–7), while the use of polar solvents, such as tetrahydrofuran (THF), acetonitrile, and N,N-dimethylformamide (DMF), resulted in quantitative

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

• Takao Shoji,
• Hiroki Fukutomi,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

• of the starting material (Table 1, entries 1–3). The best result was obtained at 25 mM concentration in dichloromethane (CH2Cl2). Although tetrahydrofuran (THF) is one of the typical reaction solvents for ACSS-assisted liquid-phase synthesis, this was not the case for the 5’-phosphitylation (Table 1

Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents

• Ugo Azzena,
• Massimo Carraro,
• Gloria Modugno,
• Luisa Pisano and
• Luigi Urtis

Beilstein J. Org. Chem. 2018, 14, 1655–1659, doi:10.3762/bjoc.14.141

• toxicities and are considered negative for genotoxicity and mutagenicity [26][27][28]. Due to these environmentally friendly characteristics, CPME and 2-MeTHF appear as versatile green alternatives to ethereal solvents such as tetrahydrofuran, dioxane, diethyl ether or methyl tert-butyl ether. Aiming to the

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• phosphine reagents are triphenyl- (Ph3P) or tributylphosphine (n-Bu3P). In recent years, advances have been made using solid supported reagents, thus facilitating work-up conditions [17][18]. The polarity of the commonly aprotic solvents used in the Mitsunobu reaction, including toluene, tetrahydrofuran or

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• solvent used; for example, dimethylformamide (DMF), tetrahydrofuran (THF), 1,4-dioxane, and toluene did not result in any formation of 4a. With the optimized conditions in hand, the use of aldehydes in the Co/Cr-catalyzed three-component coupling reaction was explored, as shown in Scheme 6. Electron-rich

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• sodium hydride in tetrahydrofuran and subsequent deprotection of Boc groups afforded L-proline immobilized calix[4]arene magnetic nanoparticles (Calix-Pro-MN) 86 (Scheme 23). In 2016, three new lower rim functionalized calix[4]arene-based L-proline catalysts 87–89 containing ester, amide and acid units

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• derivatives and utilized them in stoichiometric fashion for the synthesis of chiral tetrahydrofuran derivatives [36]. A major breakthrough was achieved in this field by the discovery of a family of conformationally flexible C2-symmetric chiral iodoarene reagents. Ishihara et al. thoughtfully designed a new

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• as follows. Propargyl derivative 3 (200 mg, 0.596 mmol) and azide compound 4 (100 mg, 0.596 mmol, 1 equiv) was dissolved in tetrahydrofuran (25 mL), and TBTA [64] (32 mg, 0.1 equiv) and [Cu(MeCN)4]BF4 (14 mg, 0.075 equiv) were added. The reaction mixture was stirred for 24 h, and the product

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• different solvents were also measured. However, no emission was observed in the dilute solutions of dichloromethane (DCM) and tetrahydrofuran (THF) because vibrational relaxation and internal conversion are promoted to reduce the PL intensity. Both compounds 1 and 2 show almost the same PL spectra in dilute

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• , tetrahydrofuran (THF), acetonitrile, and ethyl acetate (Table 1, entries 1–4), or in organochlorine solvents such as chloroform, dichloroethane (DCE), and dichloromethane (DCM, Table 1, entries 6–8), the HDA reactions smoothly proceeded at room temperature within 24 h to give the desired endo-cycloadduct 3aa in

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• reagents in tetrahydrofuran solution containing triethylamine precooled to −70 ºC with t-BuOK and after 20 min added trimethylchlorosilane, stirred for 3 h at −65 to −60 °C, and then allowed to reach room temperature and stirred for 24 h we obtained 10-(n-butyl)-11-benzenesulfonyl-10H-indolo[3,2-b

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• ]. Review Trifluoromethanesulfonyl chloride (alternate name: triflyl chloride), CAS No. 421-83-0, MW 168.53, is a colourless liquid (bp 29–32 °C) soluble in dichloromethane, tetrahydrofuran and dioxane [2]. Up to recently, the predominant use of CF3SO2Cl was for triflate and triflamide formation. Indeed

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• chromatography (PTLC) were conducted on silica gel (Silica Gel 60 N, Kanto Chemical Co., Inc. for column chromatography and Wakogel B-5F, Wako Pure Chemical Industries, Ltd. for PTLC). Tetrahydrofuran (THF), dichloromethane, and N,N-dimethylformamide (DMF) were purified by a solvent-purification system

Synthesis of 1,3-cis-disubstituted sterically encumbered imidazolidinone organocatalysts

• Jan Wallbaum and
• Daniel B. Werz

Beilstein J. Org. Chem. 2017, 13, 2577–2583, doi:10.3762/bjoc.13.254

• sieves. The prepared organocatalysts will be a useful contribution for the screening of a multitude of different organocatalytic transformations. Experimental General. All solvents were distilled before use unless otherwise stated. Tetrahydrofuran (THF) was distilled over sodium and benzophenone under an

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• mesh ASTM). Triethylamine, dimethylformamide, and tetrahydrofuran were distilled and deoxygenated prior to use. Other solvents were of reagent grade and were used without prior purification. Thymine, adenine, 3-chloropropionyl chloride, lithium aluminum hydride, sodium borohydride, and aluminium

Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

• Mukta Shaw,
• Yogesh Kumar,
• Rima Thakur and
• Amit Kumar

Beilstein J. Org. Chem. 2017, 13, 2385–2395, doi:10.3762/bjoc.13.236

• , tetrahydrofuran, toluene, and dichloroethane had an adverse effect on the reaction rate, yield and selectivity (Table 1, entries 8–11). Performing the reaction under inverse addition conditions had no impact on the selectivity of glycoside formation (Table 1, entry 12) [39][40]. Aware of the fact that HBr, which

Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• (yellow) and 2h (grey) in CH2Cl2. Absorbance spectra of 2b in methanol (orange), tetrahydrofuran (red), toluene (black), dichloromethane (green) and dimethyl sulfoxide (blue). Compounds 2a–h in dichloromethane solution in daylight (top) and under 365 nm irradiation (bottom). Synthesis of the curcumin