Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• NDI 1 in 90% yield (Scheme 1) [54]. The synthetic module for cNDIs with two substituents at the core is the 2,6-dibromo anhydride derivative 8 that can be synthesized from 7 by elementary bromine, dibromoisocyanuric acid, or 1,3-dibromo-5,5-dimethylhydantoine (DBH) in concentrated sulfuric acid, or

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• tetrapropoxycalix[4]arene 8, which used a combination of nitric acid and acetic acid, proved inconsistent in our hands (see Supporting Information File 1 for more details). We therefore conducted a careful study to optimize the reaction using a more traditional combination of nitric acid and sulfuric acid (Table 1

• ). A solution of tetrapropoxycalix[4]arene 8 in DCM was stirred at 0 °C and treated with nitric acid (70%) and concentrated sulfuric acid; after 300 min the solution had reached 18 °C, at which point the reaction was diluted with water and extracted into methylene chloride. Purification via silica gel

• generated separately, using sulfuric acid and sodium nitrite, prior to being added to the monoaminocalix[4]arene 10 at 0 °C. After diazotization (15 min), an aqueous solution of sodium azide was added dropwise. After two hours at 0 °C the reaction was extracted with ethyl acetate, and the monoazidocalix[4

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• of 1 and give rise to the corresponding 2-diarylmethylbenzimidazoles 9a–l. The best results were obtained in neat TfOH, which gave high yields of reaction products (54–86%) at room temperature after 2–3 h. Other acids were not so efficient. Thus, reactions under the action of sulfuric acid H2SO4 or

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• dibromoisocyanuric acid in fuming sulfuric acid [59]. Subsequent Stille cross coupling (to avoid phthalocyanine formation) using conditions established in the synthesis of linker 3 gave the bis(trimethylsilylethynyl) compounds 15a and 15b in nearly quantitative yields. Analogously to the above-described systems

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• strong oxidizing Jones reagent, because the oxidizing power of sulfuric acid was not enough to achieve oxidation. Interestingly, the use of microwave irradiation instead of classic heating allowed obtaining the Biginelli product in only 10 min, instead of 12 h as required for the synthesis of pyrimidines

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• trifluoromethanesulfonic acid or sulfuric acid was developed yielding basically the same polymer but avoiding residual traces of the metal [11]. These synthetic pathways often afford a gel from the dissolved monomers upon the crosslinking that is subsequently washed and dried with a significant volume loss. Still, a high

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• (center), and 3,3’-di(aminoethyl)diazocine 6b (right). Continuous lines: 100% cis and dashed lines: PSS (385 nm) at 298.15 K in acetonitrile. Key reactions in diazocine synthesis. Syntheses of the functionalized diazocines 4–7. Reaction conditions: i) Isobutylene, sulfuric acid, DCM; ii) t-BuOK, Br2, THF

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• an acid catalyst (Scheme 14). Conditions which use p-toluenesulfonic acid in acetone [58] produced acetonide 29 in 49% yield after column chromatography. Conditions which employed concentrated sulfuric acid in acetonitrile [59][60] yielded the acetonide in 76–96% yield. Large excess of 2,2

A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety

• Ilya V. Taydakov,
• Yuliya M. Kreshchenova and
• Ekaterina P. Dolotova

Beilstein J. Org. Chem. 2018, 14, 3106–3111, doi:10.3762/bjoc.14.290

• for the isolation of the β-diketones. Several methods for decomposition of copper chelates were described in literature. Usually sulfuric acid with various concentrations (10–95%) was applied [22][23][34][35], but the thiophene ring is known to be sensitive to sulfuric acid. For this reason, we

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• ; biodiesel synthesis; sulfonated carbon materials; sulfonated industrial and laboratory products; sulfonated organic materials; sulfonated silica materials; Review 1. Introduction Mineral acids (sulfuric acid, sulfonic acid, hydrochloric acid, phosphoric acid, and boric acid) as homogeneous catalysts were

• stirred solution of imidazole in dry CH2Cl2 in an ice bath. In the next step, sulfuric acid 98% was added dropwise to the reaction mixture containing the sulfonated imidazole at room temperature to obtain 1,3-disulfo-1H-imidazolium hydrogen sulfate [Dsim]HSO4 (26) as a viscous pale yellow oil catalyst

• this IL with manganese(II) chloride as a co-catalyst also exhibited excellent yield in cellobiose (61) hydrolysis in dilute aqueous sulfuric acid (Scheme 11). The authors found that the highest enhancement in the yield of the product happens at 60 °C. This may be owing to this fact that a weak

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

• chloride in THF [30]. Initially, the trimethylsilyl cyanohydrin 16 was subjected to solvolysis in ethanol with aqueous sulfuric acid. Unfortunately, those conditions resulted in displacement of the 4-chloro substituent with ethanol giving the 4-ethyl ether 17 in 35% yield. To circumvent this undesired

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

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

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• acid or other sources of C2 like ethyl orthoformate [52], diarylformamidines [53] or 1,1-dimethoxy-N,N-dimethylmethanamine [17]. Using an alternative approach, the corresponding 2-ABA was treated with acetic anhydride in concentrated sulfuric acid affording 2-methyl-6-nitro-3-(p-nitrophenyl)-3,4-DHQ

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• reported in the previous study [27], spinosyn A could be hydrolyzed to 17-pseudoaglycone under weak sulfuric acid conditions, indicating that the C9 glycosidic bond was more stable than the C17 glycosidic bond under weak sulfuric acid conditions (Scheme 2). Similar to spinosyn A, both D-forosamine and 2’,3

• sulfuric acid conditions, the 3-O-ethyl-2,4-di-O-methylrhamnose at the C17 position could be removed selectively under the weak acidic conditions to afford 5. The structure of compound 5 was also ascertained by NMR and mass spectrometry. Finally, compound 5 was glycosylated with donor 6 to provide

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• (C23H23F3N2O8) was appended to the elemental composition of FimHtr. Methods and materials for synthesis TLC was performed on silica gel GF254 (Merck). Spots were visualized under UV light and by charring with 10% sulfuric acid in ethanol and subsequent heating. Flash column chromatography was performed on

Lanyamycin, a macrolide antibiotic from Sorangium cellulosum, strain Soce 481 (Myxobacteria)

• Lucky S. Mulwa,
• Rolf Jansen,
• Dimas F. Praditya,
• Kathrin I. Mohr,
• Patrick W. Okanya,
• Joachim Wink,
• Eike Steinmann and
• Marc Stadler

Beilstein J. Org. Chem. 2018, 14, 1554–1562, doi:10.3762/bjoc.14.132

• procedures Analytical TLC: TLC aluminum sheets silica gel Si 60 F254 (Merck), detection by UV absorption at 254 nm and 366 nm. Spray reagent vanillin/sulfuric acid (prepared by dissolving vanillin (0.5 g) in 100 mL of sulfuric acid) followed by heating to about 120 °C on a hot plate. UV data were recorded on

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• -expanded product 33. After the reduction of the allylic position with LiAlH4, the treatment of monochloride 34 with concentrated sulfuric acid in ice water afforded a quantitative yield of 4,5-benzotropone (11). The above researchers also proposed a mechanism for the formation of 11 from 31 as shown in

• sulfuric acid were presumed, benzohomotropylium cation 112 was not detected from the reactions of the corresponding alcohol 114 in sulfuric acid [125]. 2.2.3. Reduction-based studies: To define the stereochemical, conformational, and dynamic properties of both benzo[7]annulenones (and related compounds

• -bromo-6-hydroxylamino-2,3-benzotropone oximes 262 were obtained. Hydrolysis of these oximes 262 with sulfuric acid gave 5-bromo-6-hydroxy-2,3-benzotropone and the 4-bromo isomer 263, which were debrominated with catalytic hydrogenation to give 239 (Scheme 41). Although 239 is capable of existing as two

One-pot synthesis of diaryliodonium salts from arenes and aryl iodides with Oxone–sulfuric acid

• Natalia Soldatova,
• Pavel Postnikov,
• Olga Kukurina,
• Viktor V. Zhdankin,
• Akira Yoshimura,
• Thomas Wirth and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 849–855, doi:10.3762/bjoc.14.70

• the generation of iodine(III) species in the oxidation of phenols [43]. In the present work, we report the development of a reliable and convenient procedure for the preparation of diaryliodonium bromides using Oxone in the presence of sulfuric acid. Results and Discussion After having investigated

• previously described reaction conditions [37][38], initial optimization studies were performed using iodobenzene and toluene as reactants for the synthesis of diaryliodonium salt 3a (Table 1). A simple mixing of the starting materials with finely ground Oxone and sulfuric acid leads to the formation of a

• -iodobenzenesulfonic acid in both cases, probably due to the high concentration of sulfuric acid in the reaction mixture. Mixing dichloromethane with acetonitrile resulted in an increased yield of 3a and a decreased amount of 4-iodobenzenesulfonic acid (Table 1, entry 3). When the reaction was carried out in pure

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• -supported sulfuric acid (MNPs-SO3H) [22]. As shown in Table 1, entries 2–4, all methods give the desired amidoalkylnaphthols in 77–97% yields. Zolfigol et al. successfully applied 1-methylimidazolium tricyanomethanide {[HMIM]C(CN)3} as the first nanostructured molten salt [23]. As depicted in Table 1, entry

• ], silica-supported perchloric acid (HClO4-SiO2) [34][35][36] and sulfuric acid [35], chlorosulfonic acid [38], sodium hydrogen sulfate (NaHSO4·H2O) [39], ferric(III) hydrogen sulfate [Fe(HSO4)3; 40], strontium(II) triflate, Sr(OTf)2; [41], copper-exchanged heteropoly acids, Cu1·5PMo12O40 (CuPMo) and Cu1

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone

• Cristina Mozo Mulero,
• Alfonso Sáez,
• Jesús Iniesta and
• Vicente Montiel

Beilstein J. Org. Chem. 2018, 14, 537–546, doi:10.3762/bjoc.14.40

• Pd0.20/C/T electrodes in the absence of sulfuric acid. Figure 9 depicts the fractional conversions and product yields as a function of the coulombic charge passed for both electrodes in the absence and presence of 0.1 M H2SO4 for comparative purposes. Even though no changes were observed in terms of

• v/v) and 0.1 M H2SO4, or (ii) 0.5 M benzophenone in ethanol 96% /water (90:10 v/v) in the absence of the sulfuric acid electrolyte in order to explore the influence of the medium acidity upon the electrochemical hydrogenation. A peristaltic pump Ismatel Reglo DIG MS/CA 2–8 provided a catholyte flow

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• of the corresponding imidoyl chlorides 10 with PCl5 in POCl3, followed by the additional reaction with trifluoromethanesulfonamide (1) and protonation by sulfuric acid (Scheme 1) [10]. In recent years, we have reported high yielding catalyst-free N-arylation by SNAr reaction of mono- or

Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline

• Benedikt C. Melzer,
• Jan G. Felber and
• Franz Bracher

Beilstein J. Org. Chem. 2018, 14, 130–134, doi:10.3762/bjoc.14.8

• hydrogenolysis experiments with 5, which were aimed at simultaneous O-debenzylation at the 7-position and conversion of the N,N-dimethylaminomethyl group at C1 into a methyl group. Hydrogenation in presence of palladium as catalyst at 1 bar in the presence or absence of small amounts of sulfuric acid gave the

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• ). The effect of inorganic protic acids was then investigated (Table 1, entries 4–6), producing moderate yields of the ring-opened product. The use of fluoroboric acid (Table 1, entry 4) and sulfuric acid (Table 1, entry 5) produced ring-opened product 26 in 45% and 48% yield, respectively, while using

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• . Sulfuric acid-catalyzed dehydrations of the benzylated hydroxyphthalimidines 3a–q in dichloromethane at room temperature resulted in the corresponding olefins 7a–q in good to excellent yields of 66–95% (Scheme 5 and Table 3). The simple reaction protocol enabled parallel operations in a Radleys Carousel 6

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• -Sulfinyl propargylamine 7k was prepared, following approach II under varying conditions (Table 2). Fluoral hydrate was dehydrated with concentrated sulfuric acid to give trifluoroacetaldehyde by distillation [93]. The reaction of trifluoroacetaldehyde with tert-butyl sulfinamide (S)-1 in the presence of