Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• Ugi–azide reaction variant described in this work. We suppose that after reduction of amide I by Schwartz’s reagent, complex II undergoes a slow, spontaneous decomposition, yielding imine III. III then reacts with TMSN3, which acts as both, an imine activator and an azide anion source. Complex IV

• spontaneous decomposition of the zirconium complex INT-1-A to the free imine species INT-3. This process is much more likely to occur via the 5-membered cyclic transition state TS-1-A than the alternative TS-1-B, as the energy barrier of 60.1 kcal·mol−1 is definitely too high for the reaction to take place

• , even at an elevated temperature. Path A with a barrier of 22.6 kcal·mol−1 is certainly more feasible. We assume that the Cp2Zr(OH)Cl species just leaves the initial complex, as this seems to be the simplest possibility in absence of any Lewis acid which could catalyze this decomposition. Scheme 9 shows

Benzothiazolium salts as reagents for the deoxygenative perfluoroalkylthiolation of alcohols

• Armin Ariamajd,
• Nils J. Gerwien,
• Benjamin Schwabe,
• Stefan Dix and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2021, 17, 83–88, doi:10.3762/bjoc.17.8

• fluoride species, which can subsequently react with the alcohol, delivering thionoester 4. β-Fluoride elimination is a known decomposition pathway of −SCF3 and has even been exploited in synthetic trifluoromethylthiolation and fluorination processes [32][33][34]. The formation of the side-product 4a could

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• authors mentioned that the employment of the previously reported conditions for the radical cyclization in the synthesis of marcfortine B (8) led to the decomposition of the starting material. It was suggested that the MOM group of 80 may contribute to undesired side reactions. Synthesis of marcfortine C

Controlled decomposition of SF₆ by electrochemical reduction

• Sébastien Bouvet,
• Bruce Pégot,
• Stéphane Sengmany,
• Erwan Le Gall,
• Eric Léonel,
• Anne-Marie Goncalves and
• Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

• expensive methods requiring a large input of energy (high temperature, high pressure). Many SF6 decomposition strategies so far developed use photoreduction, plasma discharges or even photolysis processes [10][11]. Beyond the energetic high cost of such processes, they produce side products that are highly

• reactive, corrosive and toxic [12]. Recent and really impressive works were devoted to the decomposition of sulfur hexafluoride using stoichiometric or catalytic amounts of metals (Rh, Ni, Pt) [13][14][15][16]. Organic derivatives (phosphines or bipyridine) proved efficient tools for the selective

• knowledge, electrochemical reduction of SF6 has not yet been disclosed. The decomposition of sulfur hexafluoride by electrochemistry can nevertheless be a suitable answer and interesting alternative to the previous expensive options. In this article, we describe the electrochemical behavior of sulfur

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• superior electrophile in comparison to the ester function. Indeed, this bielectrophilic reagent reacted only at the nitro group, providing the amide 20 as the sole product. The yield was quite marginal, primarily due to decomposition of the fragile ester functionality under the harsh reaction conditions

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• of absorbed water [20][21]. Two sharp weight losses were identified on the TG curves as temperature rose. The first loss within 224–327 °C may be caused by decomposition and elimination of the –SO3Na groups and the introduced small organic species in the materials [22], while the second loss at

• higher temperature of 327–448 °C may be attributed to decomposition of the support skeleton [23]. The thermal stability of referential Resin-Cu catalyst was also investigated by TG analysis (Supporting Information File 1, Figure S3), showing a high thermal stability as well [24][25][26]. The above

Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose

• Danny Lainé,
• Vincent Denavit,
• Olivier Lessard,
• Laurie Carrier,
• Charles-Émile Fecteau,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237

• 3 is the stereochemistry of the fluorine atom at C2. Finally, only decomposition originated from the use of mannose analogue 5 as substrate. The difference in terms of reactivity between 5 and 2 was unexpected since they only differ from the stereochemistry of the fluorine atom at C2 (distal to the

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• demonstrate the thermal reversibility of the gelation process. There are peak maxima at the heating and cooling phases that can be assigned to the formation of the gel structure and its decomposition. For the heating phase, a maximum was found at 45 °C, the endothermic melting process of the sample. In the

Easy access to a carbohydrate-based template for stimuli-responsive surfactants

• Thomas Holmstrøm,
• Daniel Raydan and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2020, 16, 2788–2794, doi:10.3762/bjoc.16.229

• mechanical impulse that can increase or decrease the distance between the two lipophilic tails, thus changing the amphiphilic properties of the molecule. Incorporating such molecules into the lipid bilayer of liposomes can result in the decomposition of the whole liposome when the stimuli-responsive

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• weeks, while metalloligand 3 needs to be stored in an argon atmosphere at 3 °C and 1 even needs to be stored only in an argon atmosphere at −18 °C to prevent decomposition. The reduced stability of the amine precursors compared to cage 4 might be a result from the higher electron-donating capability of

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• described for 1 led to no detectable decomposition (Figure 3, Supporting Information File 1). Biological activity and solubility The biological activities of piperine (1) and the analog 2 were compared using two different assays, namely the inhibition of either acetylcholinesterase (AChE) or β-secretase

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• decomposition upon reflux. In contrast, the treatment with trifluoroperacetic acid formed in situ in THF resulted in the expected allylic fluoride (rac)-33. Oxidative treatment under basic conditions, however, yielded the highly unsaturated diester (rac)-34, presumably via a base-promoted E1cB elimination of

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• decomposition products (Scheme 13). No reaction was observed using a 19 W CFL bulb in the absence of a PSCat. Despite acetophenone being a colorless oil with only trace absorption above 375 nm (an n–π* transition corresponding to a photon of 325 nm), it successfully functioned as a PSCat, undergoing

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• without noticeable decomposition. However, in solution under ambient atmosphere and sunlight decomposition takes place quickly, which is indicated by decolorization of a purple solution in CH2Cl2 within 3 min. 1H NMR analysis showed 6,13-pentacenequinone (15) as the degradation product. The rate of

• -difluoroanthracene. This strategy could be applicable for the synthesis of differently substituted 6,13-difluoropentacenes as well. Structures of pentacene and fluorinated pentacenes. UV–vis spectrum of F2PEN 5 in CH2Cl2. Retrosynthetic analysis of F2PEN 5. Synthesis of F2PEN 5. Decomposition of diol 13 in solution

Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• the Suzuki cross-coupling reaction published for a similar system [30], decomposition products and only 25% yield were obtained. Optimization by lowering the reaction temperature increased the yield to 91% (Scheme 1). Switching properties of porphyrin 1 Preliminary investigations on the photochemical

• , the switching efficiency slowly decreased over 100 switching cycles to ≈80% of the original value (see Supporting Information File 1, Figure S4). A thermal decomposition at 40 °C in THF was observed by a color change from red to green. Hence, the catalytic experiments were limited to 25 °C. At last

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• (Table 2). The obvious consequence being a decrease in the substrate conversion. This, however, could be compensated to some extent by longer reaction times. Based on this observation catalyst decomposition appeared to be negligible and it seemed, that the role of gold is primarily that of a Lewis acid

• (first line solvent chlorobenzene, second line solvent anisole: catalyst loading, reaction time, conversion % (isolated yield %), reaction temperature 60 °C). aPartial decomposition during column chromatography observed. Hydrohydrazidation of internal alkynes in chlorobenzene and anisole using complex 1

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• . The formylated product 10a may be purified by chromatography without decomposition. Subsequent acid hydrolysis of compound 10a leads to pyrrolidinylphosphonic acid hydrochloride 11a (Scheme 2). Similarly, pyrrolidinylphosphonic acids 11b–d were obtained from the corresponding phosphonates 6b,c,e

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• (4), FR901464 (1) [15][16], spliceostatin E (10) [41], and thailanstatin A methyl ester (123) [31] used the cross-metathesis strategy for the coupling of the diene 49 with 85, 115, and 102, respectively (Scheme 21). In order to avoid the decomposition problems encountered by Koide, the mixed cyclic

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• starting ester remained intact, while under drastic conditions (high concentration of alkali, homogeneous solutions, elevated temperatures), decomposition and/or decarboxylation occurred. However, it is possible that decarboxylation took place during the isolation of the free acid. In all cases, no desired

• malonic acid 2 was isolated from the reaction mixtures; the main part of the original material was recovered. In some experiments, variable amounts of 2-(perfluorophenyl)acetic acid (12) were obtained after acidification of the basic solution. Moreover, noticeable decomposition of 3 was observed along

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• amine/base with DMSO as an activator. Potassium ethylxanthate [64][65] and sodium sulfide as a sulfur sources in the presence of Et3N in DMSO (Table 1, entries 8 and 9) also did not furnish the desired product 2bA. A decomposition of the product was observed in the case of Na2S. Interestingly, the

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• . Condensation with 2-amino-2-methylpropan-1-ol and oxidation with NBS yielded oxazoline 6 in a good yield. Directed ortho-metalation utilizing TMPMgCl·LiCl under mild conditions and subsequent smooth formylation with DMF afforded benzaldehyde 7 (see Scheme 2). Due to rapid decomposition of 7 under ambient and

• reduction with NaBH4 to give the primary alcohol 19. In contrast to benzaldehyde 7, carbaldehyde 18 showed no decomposition at ambient temperature. While acidic hydrolysis of 19 provided exocyclic γ-lactone 20, the substitution reaction with DPPA/NaN3 yielded the primary azide in 87% yield. In accordance to

• fluorene showed such a high reactivity that rapid decomposition occurred. However, bromination was conducted by various substitution methods delivering benzyl bromide 24, which upon isolation cyclized to iminium bromide 25 in high yield. To suppress this unexpected cyclization, careful fine-adjustment of

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• photocatalytic decomposition of water on illuminated titanium dioxide (TiO2) electrodes in 1972 [27]. This critical report began the field of semiconductor HPC, and in combination with the development of organic electronics, established fundamental principles that still underpin much of the cutting-edge

• irradiated with sunlight [74]. The use of titania as a pigment had been practiced for centuries, and the observation that TiO2-based surface coatings exposed to sunlight irradiation would “chalk” (the formation of a loose white powder on the paint surface) had been recognised as the decomposition of organic

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• intermediate 4 led to a decomposition. In another experiment, the same reaction was tested at 80 °C for 1 h and intermediate 4 in addition to formylthiourea (5) were formed in low yields (Table 1, entry 7). When the reaction time was extended to 5 h, the desired three component product 6-(methylthio)-4-phenyl

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• be accompanied by side reactions such as the cleavage of tert-butyl carboxyester, [14][15] or other ester groups [16], as well as the formation of decomposition products [17][18][19][20]. Instead of focusing only on the experiments that “did work”, we decided to follow an alternative strategy

• from the reaction mixture by washing with aqueous sodium carbonate solution. The model compounds used for this study (in red: the functionality of the molecules vulnerable to side reactions). Schematic overview of the McKenna reaction including the decomposition of BTMS in protic solvents. The desired

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• magnesium turnings [31]; (2) the formation of undesired side products by thermal decomposition and exothermic reactions not suitable for industrial processes [32]; (3) the activation of a metallic surface is required and can introduce safety issues due to the high reactivity of the activated metal. Flow