gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• containing alkyne substrates could also give the corresponding gem-difluorinated compounds (in-cell method). The ex-cell electrolysis method was also applicable for gem-difluorination of alkynes. Keywords: carbon–carbon triple bonds; chemical method; electrochemistry; gem-difluorination; Introduction

• Brønsted acid, such as Tf2NH and TfOH, with Bu4NBF4 might be effective to promote the gem-difluorination of alkynes because of the in situ generation of HF equivalents (Figure 1, reaction 6, chemical method). In addition, the electrogenerated acid (EGA) [43][44][45][46][47][48][49][50][51][52] from a

• analysis in the case of 16 mA [53]. With the successful formation of (5,5-difluorohexyl)benzene (2a) by the chemical (method A) and electrochemical oxidation (method B) methods in hand, we have investigated the scope and limitations of gem-difluorination for various alkynes (Table 2). Electrochemical

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• lower to 0.004). Eleven and seven weighted conformers for compounds 2 and 3 were obtained, respectively, each forming equilibrium mixtures. The quantum chemical method for the calculation of conformer distribution was ωB97X-V/6-311+G(2df,2p)[6-311G*] [30]. The CPCM solvation model for methanol was used

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• square in its shape by changing anthracene in 1a to pyrene in 1b. To interpret the results of the diameter selectivity, the theoretical calculation using the semiempirical tight binding quantum chemical method GFN2-xTB was employed instead of the molecular mechanics used in our previous works, because it

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

• Sandeep Kumar,
• Jyotirmoy Maity,
• Banty Kumar,
• Sumit Kumar and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2022, 18, 95–101, doi:10.3762/bjoc.18.10

• chemoenzymatic method was found to be superior over the chemical method in respect of the number of synthetic steps and overall yield of the final product. Keywords: bicyclic AZT analogues; bridged homoarabinofuranosylpyrimidine nucleosides; chemical pathway; Lipozyme® TL IM; regioselective enzymatic

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• groups at the distal α-carbon or lengthening the proximal ethyl linker to a butyl linker. With such RNN phosphoramidite building blocks >3000, RNN ONs have been synthesized with high yields comparable to those of RNA synthesis, demonstrating the robustness and versatility of the chemical method. Three

Continuous-flow retro-Diels–Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

• Imane Nekkaa,
• Márta Palkó,
• István M. Mándity and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2018, 14, 318–324, doi:10.3762/bjoc.14.20

• % methanolic solution in water was added to get precipitation. The solid was filtered off and washed with water to get di-endo-3-phenyl-4a,5,8,8a-tetrahydro-5,8-ethanoquinazolin-4(3H)-one (15b). All spectroscopic data of the alternately synthesized compound were the same as those obtained by the flow chemical

• method. The protocol for the synthesis of 15b and the 1H and 13C NMR spectra of 15b are shown in Supporting Information File 1 of this study. A further attempt was made to perform the rDA reaction with 15b at 250 °C with a residence time of 15 min in MeCN. However, the formation of 16 was not observed

A semisynthesis of 3'-O-ethyl-5,6-dihydrospinosyn J based on the spinosyn A aglycone

• Kai Zhang,
• Shenglan Liu,
• Anjun Liu,
• Hongxin Chai,
• Jiarong Li and
• Lamusi A

Beilstein J. Org. Chem. 2017, 13, 2603–2609, doi:10.3762/bjoc.13.257

• spinosyn L by a chemical modification [13] (Scheme 1). However, the fermentation productivity of spinosyn J and spinosyn L is low, resulting in high cost. So we envisage that spinetoram can be synthesized via a chemical method. So far, several total syntheses of spinosyn A have been reported [17][18][19

• . Furthermore, this synthesis provides a chemical method to synthesize spinosyn analogues containing different substituents at C9-position and C17-position of the macrolide. Also, we developed an efficient synthesis of 3-O-ethyl-2,4-di-O-methylrhamnose from rhamnose in 4 steps, and this method can also be used

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• concurrently their results, in the use of both N and P as dopants in their CD syntheses. For instance, Dong et al. described the development of dual-doped hollow CDs using a wet-chemical method from glucose in the presence of 1,2-ethylenediamine (EDA) and conc. H3PO4 (Scheme 9) [40]. During the exothermic

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• . The advantages of this chemical method in comparison with other classical methods (e.g., oven drying or similar drying methods) is related to the selectivity for water (no other compounds such as solvents or volatiles will be detected), the controllable analysis temperature (room temperature or a

Electrosynthesis and electrochemistry

• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 949–950, doi:10.3762/bjoc.11.105

• Siegfried R. Waldvogel Institute for Organic Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10–14, 55128 Mainz, Germany 10.3762/bjoc.11.105 Keywords: chemical method; electrochemistry; electrosynthesis; sustainability; Since the pioneering work of Kolbe, electrochemistry and

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• surface groups accessible by the reagents will be measured using this wet-chemical method. Conclusion In summary, we have established two new functionalization methods for the covalent grafting of organic moieties onto nanodiamond using pyrazine and cyclobutene precursors for the in situ formation of