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

• fluorinating reagents, such as diethylaminosulfur trifluoride (DAST), HF, CsF, and AgF has been established as a reliable method. Electrophilic fluorinating reagents, such as 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor), N-fluorobenzenesulfonimide, and

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• (Scheme 1b). Similarly, in the absence of metal catalysts, N-fluorobenzenesulfonimide (NFSI) was found to act as a mild fluorinating reagent for activated aromatics by mechanochemistry [5]. Such a collective effort to access halogenated substrates is understandable, owning the synthetic value of organic

Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions

• José G. Hernández,
• Karen J. Ardila-Fierro,
• Dajana Barišić and
• Hervé Geneste

Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20

• techniques, in this work we studied the reactivity of N-fluorobenzenesulfonimide (NFSI) by ball milling. We corroborated that, by mechanochemistry, NFSI can engage in a variety of reactions such as fluorinations, fluorodemethylations, sulfonylations, and amidations. In comparison to the protocols reported in

• stability under environments of mechanical stress, while at the same time enough reactivity to engage in chemical transformations. In the search for solid reagents compatible with mechanochemical techniques, we became interested in evaluating the behavior of N-fluorobenzenesulfonimide (NFSI) under ball

• reagent [9][10][11], and phenylsulfonyl group transfer reagent [12][13]. In the field of mechanochemistry, the usefulness of N-fluorobenzenesulfonimide has been exemplified in the asymmetric fluorination of β-keto esters (Scheme 1a) [14], and in diastereoselective fluorinations (Scheme 1b) [15], which

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• . Normally, (E)-2-en-4-yn-1-azides 1 with electron-rich substituent groups favorably give the 5-iodopyridine 3, while for substrates containing electron-poor groups, the 2-acylpyrrole 4 is favored (Scheme 3). Then, the Reddy group developed a copper-catalyzed aminative aza-annulation of enynyl azides with N

• -fluorobenzenesulfonimide (NFSI) to provide amino-substituted nicotinate derivatives 8 in good to excellent yield (Scheme 4) [50]. The investigation showed that the electronic effect of the residue R on the substrates influences the results significantly. (E)-2-en-4-ynyl azides 1 bearing electron-donating groups had better

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• disclosed the application of N-fluorobenzenesulfonimide (NFSI) and NBS (N-bromosuccinimide), respectively, as the halogen sources, with diazoacetamide under catalyst-free conditions via a carbene pathway, which constructed 3-fluorooxindoles and 3-bromooxindoles (Scheme 1, reaction 1) [20][21]. Then, the

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• full paper later published in 1995 [58]. 1-14. N-Fluorobenzenesulfonimide (NFSI) In 1991, N-fluorobenzenesulfonimide (NFSI, 14-2) was synthesized by Differding and co-worker [59]. It was prepared from benzenesulfonimide 14-1 in good yield by its reaction with 10% F2/N2 in acetonitrile at −40 °C (Scheme

• -2), N-fluorobenzenesulfonimide (NFSI), and N-fluoro-2,6-dichloropyridinium tetrafluoroborate (5-4s) (Scheme 71) [99]. These reactions produced F-pClBzQN-X 31-2 quantitatively at 20 °C within 30 min in acetonitrile or in an ionic liquid such as 1-hexyl-3-methylimidazolinium hexafluorophosphate [hmim

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• another enantiomer of 12a (Table 3, entries 13–18) with the QD-promoted reaction affording the best ee value (Table 3, entry 13). Additionally, we tested N-fluorobenzenesulfonimide (NFSI) as an alternative fluorinating agent in a combination with DHQ-Bn and QD with the outcome being indistinguishable with

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• formation [64]. 2.2. Stereoselective benzylic fluorination of N-(2-phenylacetyl)oxazolidin-2-one using NFSI Treatment of oxazolidinone 122 with N-fluorobenzenesulfonimide (NFSI) in the presence of NaHMDS afforded the fluorinated oxazolidinone derivative 123. The reductive removal of the chiral auxiliary

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• ®, diethylaminosulfur trifluoride (DAST), or tosyl fluoride (see Supporting Information File 1, Table S1, entries 2–4), N-fluorobenzenesulfonimide (NFSI) provided the desired hydrofluorination product 4b in 36% yield (Table 1, entry 2). Carreira and co-workers reported the first hydrochlorination reaction via a cobalt

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• the method developed by Jørgensen and co-workers (Scheme 1) [20]. Thus, the aldehyde 7a (or 7b) was treated with N-fluorobenzenesulfonimide in the presence of the chiral organocatalyst 10, and after a certain period the fluorinated aldehyde product 8 was reduced in situ. Initial studies with substrate

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• nucleophiles dates back to 2002, when Kim and Park described the first use of cinchona alkaloid-based quaternary ammonium salts A (i.e., derivative A1) for the enantioselective α-fluorination of β-ketoesters 1 by using N-fluorobenzenesulfonimide (NFSI, 2) as the fluoride-transfer reagent [73] (Scheme 2). By

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• derivatives 123 via the Nazarov cyclization followed by electrophilic fluorination, has been described in 2007 by Ma et al. [65]. This reaction was catalyzed by Cu(II) triflate and proceeded in the presence of N-fluorobenzenesulfonimide (NFSI) 122 as a fluorinating reagent (Scheme 39). Scientists are

Copper-catalyzed aminooxygenation of styrenes with N-fluorobenzenesulfonimide and N-hydroxyphthalimide derivatives

• Yan Li,
• Xue Zhou,
• Guangfan Zheng and
• Qian Zhang

Beilstein J. Org. Chem. 2015, 11, 2721–2726, doi:10.3762/bjoc.11.293

• Yan Li Xue Zhou Guangfan Zheng Qian Zhang Department of Chemistry, Northeast Normal University, Changchun 130024, China 10.3762/bjoc.11.293 Abstract A copper-catalyzed aminooxygenation reaction of styrenes with N-fluorobenzenesulfonimide and N-hydroxyphthalimide derivatives has been developed

• . The aminooxygenation product could be converted into the corresponding alcohol or free amine through the cleavage of the N–O or C–N bond of the N-hydroxyphthalimide moiety. Keywords: aminooxygenation of styrenes; copper catalysts; N-fluorobenzenesulfonimide; N-hydroxyphthalimide derivatives

• addition and a nucleophilic oxygen attack [35]. Very recently, Studer and co-workers presented an aminooxygenation of alkenes with N-fluorobenzenesulfonimide (NFSI) and sodium 2,2,6,6-tetramethylpiperidine-1-olate (TEMPONa) via nitrogen-centred radical addition to the alkene followed by trapping of 2,2,6,6

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• 134a,b with ephedrine yielded a separable mixture of diastereomeric phosphonamides, trans-135a,b and cis-136a,b. The fluorination with N-fluorobenzenesulfonimide (NFSI) of either trans-135a or cis-136a was found to be strongly dependant on the base used to generate the phosphonamidate anion. The best

Organocatalytic asymmetric fluorination of α-chloroaldehydes involving kinetic resolution

• Kazutaka Shibatomi,
• Takuya Okimi,
• Yoshiyuki Abe,
• Akira Narayama,
• Nami Nakamura and
• Seiji Iwasa

Beilstein J. Org. Chem. 2014, 10, 323–331, doi:10.3762/bjoc.10.30

• -chloroaldehydes, a type of α-branched aldehyde, mediated by the Jørgensen–Hayashi catalyst 1 [8]. The reaction yielded the desired α-chloro-α-fluoroaldehydes with high enantioselectivity when the starting aldehyde was used in excess over N-fluorobenzenesulfonimide (NFSI) in the reaction. However, when an excess

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• up to 91% enantiomeric excess, with either F–TEDA (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)) in acetonitrile solution or NFSI (N-fluorobenzenesulfonimide) in dichloromethane solution as fluorinating reagents. The effects of various reaction parameters and of the

• (Table 3). Results for either fluorination (→6-F) with F–TEDA or the more soluble reagent NFSI (N-fluorobenzenesulfonimide) and NCS (N-chlorosuccinimide) for chlorination [43] (→6-Cl) are displayed in Table 3. Above ambient temperature, increasing temperatures give lower selectivity (Table 3, entries 1–3

• fluorination by choosing NFSI (N-fluorobenzenesulfonimide) as the reagent with better solubility. Reaction with NFSI in dichloroethane gave 1-F with 24% ee (5 mol % K1, 40 °C, 3 d, 66% conversion), which is close to the enantiomeric excess observed with F–TEDA in acetonitrile at the same temperature (Table 2

DBFOX- Ph/metal complexes: Evaluation as catalysts for enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones

• Takehisa Ishimaru,
• Norio Shibata,
• Dhande Sudhakar Reddy,
• Takao Horikawa,
• Shuichi Nakamura and
• Takeshi Toru

Beilstein J. Org. Chem. 2008, 4, No. 16, doi:10.3762/bjoc.4.16

• enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones 1 with N-fluorobenzenesulfonimide (NFSI) by DBFOX-Ph/metal complexes under a variety of conditions. After optimization of the metal salts, solvents and additives, we found that the fluoro-2-thiazolidinones 2 were obtained in good to high yields

• -thiazolidinones with N-fluorobenzenesulfonimide (NFSI) (Figure 1). Results and Discussion Our previous studies of the DBFOX-Ph/Ni(II)-catalyzed enantioselective fluorination of β-keto esters have shown that the optimal reaction conditions require NFSI as the fluorine source and a catalytic amount of Ni(ClO4)2

Single and double stereoselective fluorination of (E)-allylsilanes

• Marcin Sawicki,
• Angela Kwok,
• Matthew Tredwell and
• Véronique Gouverneur

Beilstein J. Org. Chem. 2007, 3, No. 34, doi:10.1186/1860-5397-3-34

• ] sigmatropic rearrangement. As anticipated and much to our delight, the doubly fluorinated alkene 3 was obtained through a succession of two electrophilic fluorinations. The electrophilic α-fluorination of the ester 4 was performed by treatment with LDA at -78°C followed by addition of N

• -fluorobenzenesulfonimide [34] (NFSI). The d.r. for this first fluorination was excellent (>20:1). The subsequent electrophilic fluorodesilylation of the resulting fluorinated silane 6 delivered 3 in excellent yield with no trace of side-products. In comparison with allylsilanes 1a-i, the fluorodesilylation of 6 was more