Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• tetrazole formation. In support of this was the fact that no lactam byproduct was detected in reactions carried out with TMSN3. As it was confirmed by detailed NMR analysis (see Supporting Information File 1), only homoregioisomeric 12a-azatetrazoles were obtained. This is in good correlation with earlier

• to be less reactive in comparison to the 12-oxo counterparts, which can be attributed to the fact that the migrating carbon atom (C-8) is less substituted than the C-13 carbon atom. Structures of all compounds were determined by a detailed NMR analysis. For B-homotetrazoles 17 and 18, a retention of

• , TMSOTf proved to be the most efficient. High yields of the desired tetrazole compounds with no lactam byproduct were obtained. The molecular structure and stereochemistry of newly synthesized tetrazoles was established by detailed NMR analysis. For compounds 13 and 14, the structure was established by

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• at 4.42 ppm and appearance of the new signal at 8.67 ppm corresponding to the triazole moiety confirmed successful click reaction under white LED exposure conditions after 4 h (Figure 3a). Kinetic studies conducted by 1H NMR analysis confirmed that the click reaction between benzyl azide and

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• in the isolation and characterization of 14 lignan derivatives including three new neolignan glycosides (1–3), four phenolic glycosides including a new compound (15), and a new cyanoglycoside (16) from the organic extracts. The structures of the new compounds were established by NMR analysis (1H and

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• catalyst-dependent (Table 1). In the presence of HG-2, the main product was dicoupled (±)-8c accompanied by the unseparable mixture of monocoupled products (±)-8a and (±)-8b. Despite the partial signal overlap, 2D NMR analysis of the (±)-8a and (±)-8b mixture was possible, and the structure of both (±)-8a

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• ][260]. The automated solid-phase approach required only two BBs with the amino group protected either with the N-TCA 79 or with the N-Cbz group 80 (Scheme 12). Compounds 81–85 served as standards to explore the conformational space of COS with different PA. NMR analysis and MD simulations revealed the

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• ) HMBC NMR analysis and confirmatory regiochemical assignment. Similarly, while the regioisomeric products arising from the N-alkylation of indazole 21 could not be separated using wet flash column chromatography or PTLC, a significantly enriched sample of the corresponding N-1 regioisomer (ratio N-1 (43

Correction: Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2021, 17, 1725–1726, doi:10.3762/bjoc.17.120

• graphical abstract is shown in Scheme 2. We apologize for any inconvenience caused. Corrected Scheme 4 of the original article. Scope of the Et3B and the DICAB-initiated SF5Cl additions on alkynes. Unless noted otherwise, isolated yields are reported. aYield estimated by 19F NMR analysis of the crude

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• one of the products was proved by NMR analysis and X-ray crystallography. A number of different substituents was introduced to the bromotriazole scaffold, where unsubstituted and electron-rich derivatives gave a good yield, while the presence of electron-withdrawing groups decreased the product yield

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• repeated attempts [14]. TLC and NMR analysis consistently indicated no conversion of 4, even after stirring at 80 °C in MeCN for 48 hours. We therefore proposed an alternative route to 5, directly from reaction of a C6 nitrile with NaN3, obviating the need for intermediate cyanoacetamide formation (Scheme

• of modified hyaluronic acid fragments [16]. 13C NMR of 5 confirmed the presence of a new quaternary carbon (tetrazole Cq, δC = 155.8 ppm) alongside disappearance of the C6-nitrile (δC = 117.0 ppm). Furthermore, 1H NMR analysis indicated the common H5 doublet was further downfield (δH = 5.64 ppm

• -phosphate 21. Deprotection utilised 0.6 equiv of Pd/C (0.1 equiv per benzyl group) and 0.6 equiv of Pd(OH)2/C to afford 21 in 72% yield after 24 h. NMR analysis of 21 confirmed the presence of a C6-tetrazole (δC = 160.8 ppm), alongside an anomeric phosphate (δP = −2.15 ppm), and 1H coupling constant data (δ

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• configuration assignment made by NMR analysis, the sulfonate derivative 21 from 14af was prepared by reaction with tosyl chloride. For compound 21, we were able to obtain single crystals suitable for X-ray analysis and the X-ray diffraction studies on 21 confirmed undoubtedly its trans-configuration. The ORTEP

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• using 0.193–0.771 mmol of α-1a and 25 ± 5 g of liquid SO2; α/β ratios were determined by 1H NMR analysis of the crude reaction mixture. b56% yield when 1.1 equiv NuH was used. c67% yield when 1.0 equiv NuH was used. d34% yield when 1.0 equiv NuH was used. eReaction conditions: 1.2 equiv NuH, 43 g liquid

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• without any catalyst (Table 1, part B, entry 8) produced a white precipitate that, according to X-ray analysis, was the target triazolobenzodiazepinone 7aaa (Figure 5). Similarly, the IAAC of the Passerini product under catalyst-free conditions was described earlier [22]. The 1H NMR analysis is less

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• , DCC/DMAP, DCC/1-hydroxybenzotriazole (HOBt), bromotris(dimethylamino)phosphonium hexafluorophosphate (BroP), or O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU) and by 31P NMR analysis. The results indicated that the intermediates, benzotriazolyl phosphonates, were more

• phosphonodepsipeptide sodium salt 180. By using a similar method, two acyclic analogues 183 and 186 were synthesized as well. The macrocyclic phosphonodepsipeptide 180 and the two acyclic analogues 183 and 186 were evaluated for their potential as inhibitors. The NMR analysis results indicated that the conformation of

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• experiments did not determine preference for tautomer A or B of compound 5a, it was analysed in its deprotonated form C (CD3OD/D2O/NaOD). Interestingly, that the 13C NMR spectrum of 5a in basic medium revealed a similar chemical shift for carbon C(2’’) (40.9 ppm) as in neutral CD3OD. The 13C NMR analysis of

Unexpected rearrangements and a novel synthesis of 1,1-dichloro-1-alkenones from 1,1,1-trifluoroalkanones with aluminium trichloride

• Beatrice Lansbergen,
• Catherine S. Meister and
• Michael C. McLeod

Beilstein J. Org. Chem. 2021, 17, 404–409, doi:10.3762/bjoc.17.36

• trifluoromethyl to a trichloromethyl group with AlCl3 has been previously reported [30][31][32], investigations into the analogous transformation of aliphatic CF3 groups has been limited to adamantly-trifluoromethyl moieties [33][34]. An NMR analysis of the crude product mixture obtained using our original

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• observation of thiophenium ions 77Me-Cl and 77Me-Br (Scheme 21). 19F NMR analysis showed significant downfield shifts for the signal of the CF3 group compared to the neutral precursors, characteristic of α-(trifluoromethyl)carbenium ions. However, and as expected, the 13C NMR spectra showed considerable

Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity

• Dmitrii A. Shabalin,
• Evgeniya E. Ivanova,
• Igor A. Ushakov,
• Elena Yu. Schmidt and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29

• are noteworthy. It was found that all tested hydroxypyrrolines 1a–e and hydrazides 2a–g afforded the corresponding tetrahydropyridazines 3 (according to 1H NMR analysis of the crude reaction mixtures). However, due to the difficulties associated with their isolation and purification only few examples

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• cell lines [44]. Here, the incorporation of CF3 and CF3O groups as NMR reporters into the tumour-targeting drug conjugates enabled the direct investigation of the mechanism of the pro-drug metabolic cleavage and the pharmacophore release by real-time 19F NMR analysis. 19F NMR was also employed as a

• concentration, high sensitivity 19F NMR has been employed to offer unique opportunities for their sampling and characterization in situ [50]. Prosser et al. demonstrated the utility of this approach when employing a combination of variable temperature (VT) 19F NMR analysis and CD spectroscopy to study the near

• innate flexibility of IDPs imposes tremendous technical challenges to standard NMR analysis, as pronounced conformational averaging gives rise to narrow signal dispersion and low signal-to-noise ratios. Indeed, unless more sophisticated NMR techniques are employed, the combination of these two effects

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• between the keto and the enol tautomer is given based on the 1H NMR analysis. These results are consistent with the report by Tan and collaborators [55] and are evidence to help understand the reaction mechanism. Although detailed mechanisms for these reactions remain to be elucidated, the literature has

A sustainable strategy for the straightforward preparation of 2H-azirines and highly functionalized NH-aziridines from vinyl azides using a single solvent flow-batch approach

• Michael Andresini,
• Leonardo Degannaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20

• , into the coil reactor maintained at the temperature of 130 °C, and the residence time varied by adjusting the flow rate (Table 2). The reaction yield was calculated by 1H NMR analysis of the crude. In details, conversion of 1a in 2a increased from 33% to >99% by adjusting the residence time from 4 min

Silver-catalyzed synthesis of β-fluorovinylphosphonates by phosphonofluorination of aromatic alkynes

• Yajing Zhang,
• Qingshan Tian,
• Guozhu Zhang and
• Dayong Zhang

Beilstein J. Org. Chem. 2020, 16, 3086–3092, doi:10.3762/bjoc.16.258

• . aThe E/Z ratio was determined by 1H NMR analysis of the reaction mixture after the reaction reached completion. Substrate scope for the synthesis of the β-fluorovinylphosphonates 3 using dimethyl phosphite. Reaction conditions: aromatic alkyne 1 (0.2 mmol), AgOAc (0.02 mmol), dimethyl phosphite (0.4

Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256

• reported. aYield estimated by 19F NMR analysis of the crude mixture using 2-fluoro-4-nitrotoluene as an internal standard. Scope of the Et3B and the DICAB-initiated SF5Cl additions on alkynes. Unless noted otherwise, isolated yields are reported. aYield estimated by 19F NMR analysis of the crude mixture

Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD^®/Olah’s reagent under solvent-free conditions

• Yumeng Liang,
• Akihito Taya,
• Zhengyu Zhao,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254

• mL), and the combined organic layer was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The yield was determined by 19F NMR analysis of the crude mixture by using C6H5OCF3 (40.0 μL, 0.3 mmol, 1.0 equiv) as an internal standard. The residue was purified by silica gel

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• concluded from NMR analysis, this also applies to the adenosine derivative reported here. However, standard reaction conditions that should preferentially lead to the 2’-O-TBDMS isomer, here favored formation of the 3’-O-isomer in fourfold excess, and we were not able to find conditions that would reverse

Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• and 6c in high yields. Furthermore, iodopyrazine was applicable to furnish 6d in 63% yield. Finally, a mechanistic study of the reaction was carried out. First, the active species of the reaction was investigated by NMR analysis. The generation of Cu(I)–CF3 was observed by mixing benzimidazoline 2 and