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Search for "reaction mechanism" in Full Text gives 546 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

  • Koustav Singha,
  • Imran Habib and
  • Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

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  • electrophilicity in case of electron-withdrawing groups. Imidazole N-oxides bearing naphthyl (23g) and n-butyl (23f) groups at the N-1 position also afforded the desired products in 93% and 95% yields, respectively. Notably, no product was isolated in case of glyoxal monoxime. The plausible reaction mechanism
  • products. Interestingly, unstable enones formed from the CH-acids like 4-hydroxy-6-methylpyrone and 4-hydroxycoumarin also successfully gave the desired products 35p and 35q under the standard conditions. The proposed reaction mechanism proceeded through the same pathway as outlined in Scheme 5. The
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Published 22 Nov 2022

Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)

  • Yukiko Karuo,
  • Atsushi Tarui,
  • Kazuyuki Sato,
  • Kentaro Kawai and
  • Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1567–1574, doi:10.3762/bjoc.18.167

Graphical Abstract
  • 2n was 32% (Table 2, entry 13). In the case of aminophenol (3o), nucleophilic addition occurred predominantly at the phenoxide position and the product was obtained in moderate yield (Table 2, entry 14). An aryl iodide also participated in the reaction (Table 2, entry 15). We propose the reaction
  • mechanism shown in Scheme 2 [15][26]. In the reaction medium, 3 is deprotonated by KOH to generate phenoxide ion 4, which acts as a base and as a nucleophile. Removal of an acidic hydrogen from halothane provides 5, which is a key intermediate in the reaction. Intermediate 5 is sufficiently electrophilic to
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Published 21 Nov 2022

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

  • Pavel A. Topanov,
  • Anna A. Maslivets,
  • Maksim V. Dmitriev,
  • Irina V. Mashevskaya,
  • Yurii V. Shklyaev and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

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  • mechanism of formal [4 + 1] cycloaddition of FPDs 1 with diazooxindoles 2 (negative charge delocalization is colored in blue); B) plausible base-promoted reaction mechanism of FPD 1i and 3-bromooxindole (4, negative charge delocalization is colored blue). Reaction of FPD 1a and diazooxindole 2a in different
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Published 10 Nov 2022

Molecular and macromolecular electrochemistry: synthesis, mechanism, and redox properties

  • Shinsuke Inagi and
  • Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 1505–1506, doi:10.3762/bjoc.18.158

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  • of organic molecules and the estimation of subsequent reactions, resulting in a much better understanding of the reaction mechanism. Furthermore, because organic electrosynthesis requires the setting of many complex parameters, such as applied potential, current density, electrolyte, temperature, and
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Published 26 Oct 2022
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  • the asymmetric ring opening of epichlorohydrin with different phenols in the presence of 2f (0.5 mol %), resulting in good yields and high ee (up to 99%). Further application of chiral Co–salen complexes and their reaction mechanism will be addressed in the due course. Representative asymmetric Co
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Published 10 Oct 2022

Make or break: the thermodynamic equilibrium of polyphosphate kinase-catalysed reactions

  • Michael Keppler,
  • Sandra Moser,
  • Henning J. Jessen,
  • Christoph Held and
  • Jennifer N. Andexer

Beilstein J. Org. Chem. 2022, 18, 1278–1288, doi:10.3762/bjoc.18.134

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  • relevant, as the ATP produced will be directly used by the main reaction. In future, it will be interesting to investigate the detailed reaction mechanism including the effects of the polyP chain length and counter ions as well as to study the thermodynamic activity of the enzymes. Especially in reaction
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Published 20 Sep 2022

Ferrocenoyl-adenines: substituent effects on regioselective acylation

  • Mateja Toma,
  • Gabrijel Zubčić,
  • Jasmina Lapić,
  • Senka Djaković,
  • Davor Šakić and
  • Valerije Vrček

Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133

Graphical Abstract
  • /bjoc.18.133 Abstract A series of N6-substituted adenine–ferrocene conjugates was prepared and the reaction mechanism underlying the synthesis was explored. The SN2-like reaction between ferrocenoyl chloride and adenine anions is a regioselective process in which the product ratio (N7/N9-ferrocenoyl
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Published 19 Sep 2022

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH4I

  • Shang-Feng Yang,
  • Pei Li,
  • Zi-Lin Fang,
  • Sen Liang,
  • Hong-Yu Tian,
  • Bao-Guo Sun,
  • Kun Xu and
  • Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

Graphical Abstract
  • . To demonstrate the practicability of the reaction, a scale-up reaction of ethyl acetoacetate (1a, 28 mmol, 3.64 g) and thiourea (2a,14 mmol, 1.05 g) was carried out under the optimized conditions to give 3a in 50% yield (Scheme 3). In order to better understand the iodide-mediated reaction mechanism
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Published 15 Sep 2022

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

  • Jin Yang,
  • Dang-Wei Qian and
  • Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

Graphical Abstract
  • . Additional experiments were conducted in order to clarify the reaction mechanism. Under standard conditions, only pyridin-2-ylmethyl diphenylphosphinate (3aa) was produced, and the Pudovik adduct (hydroxy(pyridin-2-yl)methyl)diphenylphosphine oxide (4aa) was not detected (Scheme 4a). The control experiment
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Published 09 Sep 2022

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

  • Mana Kitano,
  • Tsuyoshi Saitoh,
  • Shigeru Nishiyama,
  • Yasuaki Einaga and
  • Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

Graphical Abstract
  • propose a reaction mechanism (Table 2). First, we carried out the electrolysis of 1 in MeCN–MeOH to confirm whether the reaction intermediate is a radical or cationic species (Table 2, entry 1). As a result, methyl cumyl ether, a methoxy adduct to the benzyl position of 1, was obtained as the main product
  • Et4NClO4 (0.1 M). Scan rate: 100 mV/s. Proposed reaction mechanism of electro-conversion of cumene (1) into acetophenone (3). Electro-conversion of 1. Control electrolysis experiments of 1a. Supporting Information Supporting Information File 244: Characterization data and 1H NMR spectra of isolated
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Published 07 Sep 2022

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

  • Nguyen Tran Nguyen,
  • Vo Viet Dai,
  • Nguyen Ngoc Tri,
  • Luc Van Meervelt,
  • Nguyen Tien Trung and
  • Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

Graphical Abstract
  • -Trisubstituted pyrrolidine-2,3-dione derivatives were prepared from the above mentioned 2-pyrrolidinone derivatives and aliphatic amines, which exist in enamine form and are stabilized by an intramolecular hydrogen bond. A possible reaction mechanism between 3-pyrroline-2-one and aliphatic amine (CH3NH2) was
  • enamine derivatives. As compared to glacial acetic acid [42], ethanol has showed to be the best solvent for the synthesis of these pyrrolidine-2,3-diones and a dramatic increase in the yield of the desired products was also observed. In addition, understanding of the reaction mechanism at the molecular
  • )ethylene-1,5-diphenylpyrrolidine-2,3-dione in the present work. To the best of our knowledge, it is the first time the reaction mechanism between 3-pyrrolin-2-one derivative and methylamine was explained in detail via computational studies. Results and Discussion A model reaction of benzaldehyde (1a
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Published 31 Aug 2022

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

  • Md Azadur Rahman,
  • Kana Kuroda,
  • Hirofumi Endo,
  • Norihiko Sasaki,
  • Tomoaki Hamada,
  • Hiraku Sakai and
  • Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

Graphical Abstract
  • example, there are two pseudo-tetrasaccharide structures 11a and 11b, which would be hard to separate by preparative-scale purification techniques. Reaction mechanism There are two possible pathways for chain elongation in electrochemical polyglycosylation (Figure 7). In path a, monosaccharide 1a is
  • hexasaccharide 6a (5%, 3.1 μmol, 8.2 mg). We ran the process up to the third cycle and isolated octasaccharide 8a (3%, 2.3 μmol, 7.6 mg), which was never isolated after the first cycle and the second cycle. These results also supported the proposed reaction mechanism path a in Figure 7. Conclusion In conclusion
  • , we have developed a practical method to synthesize longer-chain oligosaccharides within a short period of time through electrochemical polyglycosylation. A rational reaction mechanism was proposed based on oxidation potentials of the oligosaccharides, and further modification of the protocol was
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Published 30 Aug 2022

Electrogenerated base-promoted cyclopropanation using alkyl 2-chloroacetates

  • Kouichi Matsumoto,
  • Yuta Hayashi,
  • Kengo Hamasaki,
  • Mizuki Matsuse,
  • Hiyono Suzuki,
  • Keiji Nishiwaki and
  • Norihito Kawashita

Beilstein J. Org. Chem. 2022, 18, 1116–1122, doi:10.3762/bjoc.18.114

Graphical Abstract
  • (Table 4, entry 2). Scheme 2 depicts a plausible reaction mechanism. We assume that the current reaction follows a similar mechanism as described in Abushanab’s report [12]. In addition, the current reaction indicated the generation of an EGB (electrogenerated base) [26][27][28][29]. The electrochemical
  • cyclopropanetricarboxylates. Previous reports (reactions 1–3) and this work (reaction 4). Plausible reaction mechanism. EGB = electrogenerated base. Reaction optimization. Effect of electricity around 1 F/mol and type of electrochemical cell. Scope and limitations. Scale-up experiments. Supporting Information Supporting
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Published 29 Aug 2022

A Streptomyces P450 enzyme dimerizes isoflavones from plants

  • Run-Zhou Liu,
  • Shanchong Chen and
  • Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

Graphical Abstract
  • coclaurine [28]. The absence of the product 1 in vitro is reasonable because the biosynthesis of 1 requires an additional methyltransferase from S. cattleya for the methoxy group formation. Substrate scope and reaction mechanism After identification of CYP158C1 as the isoflavone dimerization enzyme, we next
  • , Supporting Information File 1). Other plant polyketides, such as anthraquinones 19 and 20 and phenylpropanoids 21–24, failed to be dimerized. The reaction mechanism of P450-mediated phenol dimerization is believed to involve oxidative radical–radical coupling, though other mechanisms, such as radical
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Published 26 Aug 2022

Electrochemical formal homocoupling of sec-alcohols

  • Kosuke Yamamoto,
  • Kazuhisa Arita,
  • Masashi Shiota,
  • Masami Kuriyama and
  • Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

Graphical Abstract
  • ]. The addition of water may be also important to achieve high diastereoselectivity in the present reaction. On the basis of the results of the control experiments, a plausible reaction mechanism is depicted in Scheme 6. Initially, sec-alcohol 1 is oxidized by an anodically generated Br+ species to
  • utility of this transformation. Further investigations of the reaction mechanism are currently underway in our laboratory. Strategies for the synthesis of vic-1,2-diols. Substrate scope. Reaction conditions: 1 (1.0 mmol), Et4NBr (0.1 equiv), imidazole (0.05 equiv), MeCN (5 mL), H2O (125 μL), 50 mA cc, 4 F
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Published 22 Aug 2022

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

  • Koichi Mitsudo,
  • Haruka Inoue,
  • Yuta Niki,
  • Eisuke Sato and
  • Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

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  • 72% yield with good selectivity (89%). Both 1f and 1g could be used in this reactions, and the corresponding alcohols 3f and 3g were obtained as major products. Mechanistic studies To gain further insight into the reaction mechanism of the chemoselectivity of a Pd/C cathode system, some additional
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Published 19 Aug 2022

A versatile way for the synthesis of monomethylamines by reduction of N-substituted carbonylimidazoles with the NaBH4/I2 system

  • Lin Chen,
  • Xuan Zhou,
  • Zhiyong Chen,
  • Changxu Wang,
  • Shunjie Wang and
  • Hanbing Teng

Beilstein J. Org. Chem. 2022, 18, 1032–1039, doi:10.3762/bjoc.18.104

Graphical Abstract
  • cyanoformamides [75]. However, all of these works are primarily focused on the substitution reaction of N-substituted carbonylimidazoles. In our previous work, we conveniently prepared formamides by reducing N-substituted carbonylimidazoles with NaBH4 [62] (Scheme 1). The reaction mechanism shows that the H− ion
  • had a large steric hindrance like 7b, but also had a strong conjugation system, took much longer time (6 h) to complete the reaction. As shown by the reaction mechanism, the methyl group was converted from the carbonylimidazole moiety by full reduction and therefore no competing overalkylation
  • carboxylic acids or isocyanates. The acetamide group was well tolerated in our reduction, implying our method showed interesting reduction selectivity. The synthesis of formamides and monomethylamines. The possible reaction mechanism. RDS = rate determining step. Optimization of the reaction conditions.a
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Published 17 Aug 2022

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

  • Hui Zheng,
  • Ying Han,
  • Jing Sun and
  • Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

Graphical Abstract
  • relative configuration. For explaining the formation of the two kinds of the compounds, a plausible reaction mechanism was proposed on the basis of the previous works [30][31][32][33][34][35] and the present experimental results (Scheme 2). As described in the previous work, TBAF can act as an effective
  • hours afforded the expected product 4d in 45% yield. This result clearly showed that the initially formed functionalized cyclopentene 3b could be smoothly transferred to the carboxamide-bridged dicyclopentene 4d, which also strongly supported the above proposed reaction mechanism. Conclusion In summary
  • stereochemistry of the reactions was clearly elucidated and a rational reaction mechanism was proposed. The reactions have the advantages of using readily available reagents, mild reaction conditions, good yields, and high diastereoselectivity, and have potential synthetic applications in organic and medicinal
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Published 08 Aug 2022

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

  • Shani Zev,
  • Marion Ringel,
  • Ronja Driller,
  • Bernhard Loll,
  • Thomas Brück and
  • Dan T. Major

Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97

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  • inherent chemistry in these reactions and also points to some understanding of the possible thermodynamic and kinetic control in the enzyme. Results Reaction mechanism To better understand the HP and IE reaction pathways, we performed quantum mechanics (QM) calculations using density functional theory (DFT
  • -house code which modifies parameters for cations from existing parameters for neutral molecules. For each intermediate in the reaction mechanism (path HP and IE) we created 100 conformers which were subsequently clustered (a cluster width of 1.0 Å was used). For each unique conformer we performed QM
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Published 04 Aug 2022

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

  • Naoki Kise and
  • Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

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  • subsequent transformation to 2-cyanonaphthalene-1-ol (3a). Presumed reaction mechanism of electroreductive coupling of 1 with 2a and subsequent transformation to products 3 and 4. Electroreductive coupling of 1a with 2c and subsequent treatment with 1 M HCl. Electroreductive coupling of 1a–h with 2a and
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Published 02 Aug 2022

On Reuben G. Jones synthesis of 2-hydroxypyrazines

  • Pierre Legrand and
  • Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 935–943, doi:10.3762/bjoc.18.93

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  • result of this reaction, then the less likely occurrence of intermediates 7 and/or 8 could account for this result. However, since from α-ketoaldehydes, this reaction is achieved in the presence of sodium hydroxide, a far more complex reaction mechanism is likely; although to the best of our knowledge
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Published 29 Jul 2022

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

  • Sadanobu Iwase,
  • Shinsuke Inagi and
  • Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

Graphical Abstract
  • resulted in much lower product yields. The detailed reaction mechanism was clarified based on the cathodic reduction of 1 in the presence of deuterated acetonitrile, CD3CN. Keywords: bis(phenylthio)difluoromethane; cathodic reduction; deuteration; o-phthalonitrile mediator; (phenylthio)difluoromethylation
  • both radical and anionic intermediates. In order to further clarify the reaction mechanism, the indirect cathodic reduction of compound 1 was performed in the presence of α-methylstyrene in MeCN containing cumene (iPrC6H5) and isopropyl alcohol (iPrOH). The former works as a hydrogen radical source
  • the formation of adduct 4 to some extent (from 0% to 14% yield) as shown in Table 3. Therefore, iPrOH seems to promote the radcal addition rather than reduction although the reason has not been clarified yet. Reaction mechanism Although the cathodic reduction of perfluoroalkyl halides usually involves
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Published 20 Jul 2022

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

  • Mio Matsumura,
  • Kaho Tsukada,
  • Kiwa Sugimoto,
  • Yuki Murata and
  • Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

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  • standard conditions did not proceed (Scheme 1, reaction 2). The reaction mechanism for this coupling reaction is presently unclear. We propose that the reaction mechanism may be similar to that of the C(sp)–Se bond formation of terminal alkynes with diaryl diselenides reported by Stieler and Schneider [31
  • ]. Based on this report and the above control experiments, a plausible selenation reaction mechanism is shown in Figure 3. The first step of the reaction involves the generation of intermediate A by the oxidative addition of the Cu(I) catalyst to the diselenide 2. The terminal alkyne coordinates with
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Published 19 Jul 2022

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

  • Shao-Cong Zhan,
  • Ren-Jie Fang,
  • Jing Sun and
  • Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

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  • developed the practical synthetic values of the well-known Levy reaction by using inactivated indole derivatives. The outcome of diastereoselectivity of the reaction was clearly elucidated by determination of the several single crystal structures and the analysis of the reaction mechanism. The experimental
  • . Synthesis of 3,3'-(arylmethylene)bis(2-methyl-1H-indole). Reaction conditions: 2-methylindole (1.0 mmol), aromatic aldehyde (0.5 mmol), CuSO4 (0.1 mmol), toluene (6.0 mL), 110 °C, 3 h. Isolated yields are shown. Proposed reaction mechanism for the multicomponent reaction. Optimization of reaction
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Published 07 Jul 2022

A trustworthy mechanochemical route to isocyanides

  • Francesco Basoccu,
  • Federico Cuccu,
  • Federico Casti,
  • Rita Mocci,
  • Claudia Fattuoni and
  • Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 732–737, doi:10.3762/bjoc.18.73

Graphical Abstract
  • attributed to their probable reaction mechanism where the nitrogen atom not only promotes the enolate derivative formation as already described in literature [33][34] but it may also generate a positively charged intermediate at the transition state [35], enhancing the nucleophilic substitution. Obviously
  • isocyanide purity (Figure 2), even though, in some cases, a small amount of sulphonyl derivatives or solvent residues can be spotted. These little impurities are due to the isocyanide instability and difficulty in being held. In light of what was said above, it makes sense to hypothesise a possible reaction
  • mechanism (Scheme 4). The single equivalent of triethylamine should be able to activate the tautomerism of the formamide through an acid–base reaction [33][42][43][44][45]. The triethylammonium salt produced can be restored as triethylamine through the action of Na2CO3. This proton transfer allows the
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Published 22 Jun 2022
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