Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• HFIP. The regioselective amination of benzylic positions in alkylarenes [82] and ethers [83] directed by steric effects was achieved by the development of sterically hindered “bowl-shaped” imide-N-oxyl radical precursors (Scheme 7). The presented example with a sterically hindered N-hydroxyimide

• in the case of chelating substrates [80]. In order to avoid the usage of transition metal salts, metal-free oxidative systems for the generation of imide-N-oxyl radicals were proposed. In the majority of such systems, an N-hydroxyimide undergoes single-electron oxidation photochemically by a

• homogeneous process, which once initiated on the TiO2 surface, can produce multiple molecules of product without additional light absorption. Another approach to the generation of imide-N-oxyl radicals under mild conditions without transition metal salts as co-catalysts employs electric current as the oxidant

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• kind of reaction engaging the azido group in the CD chemistry is the phosphine imide reaction [30][31]. This transformation involves triphenylphosphine and carbon dioxide to convert azide into isocyanate [31], allowing coupling with amines or other nucleophile groups. It is interesting to note that the

• methylated primary rim based on the remarkable methylation ability of methyl tosylate with relatively mild bases at solvent-free conditions has been developed. It has been proved that using Lewis acid in the phosphine imide reactions with CDs can increase the reactivity of some low-reactive compounds, giving

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

• ] could be simplified by in situ generation of the catalyst. Moreover, in the debromination of norbornene imide 11, the expected Diels−Alder adduct with furan was not obtained, but compound 12 incorporating a tetrahydrofuran ring at position 2, presumably by radical reaction (Figure 2) [19][20]. We

• (conditions a), imide 44 was the major product accompanied by a small amount of janusene imide derivative 45 (7:1 ratio). The formation of the intermediate alkene 43 was observed spectroscopically only in the milling reaction of 42 alone (an indicative 1H NMR signal of bicyclo[2.2.1] moiety at 5.28 ppm

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• -formyl product iii, a possible intermediate on the path to product i via imide hydrolysis. To better understand the mechanism of photocleavage and the appearance of the formyl product iii, we first identified the 2-nitroaryl-derived byproducts produced in this reaction. Model compound 1 was subjected to

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• alkaloids, (+)-deethylibophyllidine (88) and (+)-limaspermidine (89) from the reaction of para-dienone imide 84 with benzylamine (85) in the presence of bifunctional thiourea organocatalyst (Scheme 4) [56]. 1.6 Reactions catalyzed by chiral binol-derived phosphoric acids Binol-derived chiral phosphoric

• derivatives. Intramolecular 6-exo-trig aza-Michael addition reaction. Asymmetric aza-Michael/Michael addition cascade reaction of 2-nitrobenzofurans and 2-nitrobenzothiophenes with 2-aminochalcones catalyzed by squaramide derivative. Asymmetric aza-Michael addition of para-dienone imide to benzylamine

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

• aromatics such as phenol, cresol, and naphthalene were fluorinated in chloroform at 22 °C (Scheme 18). The N-F imide reagent 7-1a fluorinated the sodium salt of diethyl 1-methylmalonate at −10 °C to give the corresponding fluoro product in high yield (96%). Later (1991 and 1992), the same laboratory

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• of the imide slowly forms. After stirring for 24–36 h, the precipitate is filtered, and the filtrate, after washing with ethanol or diethyl ether, is acidified to precipitate the imide. In the course of the work-up, Guareschi noticed the formation of copious gas, bubbling from the solution of the

• ammonium salt of the dicyanoimide. A similar bubbling could be observed when the crystallized imide was treated with ammonia. Guareschi collected the gas evolved from the reaction, and much to his surprise, identified it as the hydrocarbon corresponding to the more substituted alkyl residue of the starting

• carbonyl derivative. Guareschi found that the fragmentation was quantitative when an ethanolic solution of the imide was treated with magnesium hydroxide, poorly soluble but sufficient to ionize the cyanopyridone. It should be pointed out that the identification of gaseous compounds was not at all trivial

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• -sustainable semiconductors are slowly being replaced by a new generation of semiconductors. Graphitic carbon nitride (g-CN) is a metal-free polymeric semiconductor that is mainly composed of carbon and nitrogen elements by tri-s-triazine, triazine imide, or heptazine repeating units [16][17][18]. g-CN

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• interaction with the reagents. As a result, several hollow fibres-immobilised catalysts have been prepared and applied in flow scenarios [112]. A titania-, zirconia- and silica-implanted polyamide-imide (PAI) hollow fibre was grafted with aminosilane functional groups in order to create a bifunctional

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• the optimal reaction conditions for electrophilic allylation of 2b with 1a in hand, we turned to demonstrate the versatility of this method. In our previous work relating to nucleophilic allylation of imide derivatives, we succeeded the syntheses of N-carbonyl-functionalized γ-hydroxy amides bearing

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

• -Fluor®, CH2Cl2, 0 °C to rt, 27 h, 61% yield of two isomeric bromofluorinated products in a ≈11:10 ratio). We continued our synthetic explorations with unsaturated fused ring systems. Our first choice was the easily accessible N-benzylated cis-tetrahydrophthalic imide 7. Unfortunately, both bromo- and

• trans-fused tetrahydrophthalic imide (rac)-10 that was previously unknown in the literature. The synthesis started from the trans-tetrahydrophthalic anhydride (rac)-9 [34], and the reaction of (rac)-9 with BnNH2 in the presence of Et3N in toluene under reflux [35] gave the desired product (rac)-10 in 42

• intramolecular cyclization impossible. Therefore, we attempted the bromofluorination of the easily accessible oxabicycloheptene derivative 18. Unfortunately, the reaction led to a complex mixture, without any halofluorinated product (Scheme 11). As an alternative approach, the N-benzyl imide 19 was investigated

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• naphthalene diimde analogue (NDI) equipped at the imide positions with two guanidinio-carbonyl-pyrrole (GCP) pendant arms interacted significantly stronger with ds-DNA at pH 5 than at pH 7, due to reversible protonation of the GCP arms. This was consequence of a pH-switchable threading intercalation into ds

• and 115 nm at ratios of r = 0.1 and 0.5, respectively. Higher ratios resulted in even larger particle size, which eventually ended in precipitation. Conclusion We designed and synthesized a novel naphtalene diimide analogue equipped at imide positions with two guanidinio-carbonyl-pyrrole (GCP) pendant

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

• and co-workers first synthesized the NFPYs [186]. Further synthesis of similar compounds resulted in the synthesis of N-fluorobis(phenyl)sulfonimide (NFSI) [187], N-fluorobis[(trifluoromethyl)sulfonyl]imide [188][189], N-fluoropyridinium salts [186], N-fluorosaccharinsultam and 4-nitro-substituted N

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• is substituted at the imide positions, although such substituted NDI derivatives tend to hydrolyse at the imide positions in basic aqueous environment [24]. It is therefore important during the synthesis and processing to work under acidic to neutral conditions to ensure the stability of the

• molecules. In addition to the pH value, the hydrolysis also depends on the position of cationic ammonium groups, namely, the distance of the charged group from the imide position is proportional to its stability [24]. However, too long side chains can interfere with threading intercalation into ds-DNA/RNA

• . As a compromise, a 3-trimethylammoniumpropyl substituent was uniformly introduced at both imide positions (Figure 1). As shown previously by Würthner and co-workers, amine and halogen substituents at the NDI 2,6-positions have a remarkable effect on the NDI chromophore, as they endow the otherwise

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• metathesis polymerisation (ROMP) to generate facially amphiphilic polymers [182][235][237][238]. Ilker et al. employed the DAC between alkyl pentafulvenes and maleic anhydride to initially prepare norbornene anhydride monomers that could be further functionalised to afford norbornene imide monomers (Scheme

• phospholipid unilamellar vesicles at low concentrations (5 µg/mL), and in a dose and molecular weight dependent fashion, indicating their potential antimicrobial properties. Further studies revealed that co-polymerisation of norbornene imide monomers with different alkyl groups provided optimal antimicrobial

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• light photoredox catalysts and characterized by methods of optical spectroscopy and electrochemistry in comparison with one unsubstituted naphthalene diimide as reference. The core-substituted naphthalene diimides differ by the alkyl groups at the imide nitrogens and at the nitrogens of the two

• substituents at the core in order to enhance their solubility in DMF and thereby enhance their photoredox catalytic potential. The 1-ethylpropyl group as rather short and branched alkyl substituent at the imide nitrogen and the n-propyl group as short and unbranched one at the core amines yielded the best

• herein the synthesis and characterization of NDI 1 as unsubstituted chromophore reference and cNDIs 2–6 as potential visible light photoredox catalysts. The cNDIs 2–6 differ by the alkyl groups at the imide nitrogens and at the nitrogens of the two core substituents at the core in order to enhance their

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• phthalimide segment even containing a large substituent on the imide nitrogen atom is able to flip readily between two sides of the plane defined by bridging oxygen atoms. The conformational fluxionality of the macrocyclic ring would be beneficial to molecular recognition. To gain a deep insight into the

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• mechanochemically (Scheme 5). In this molecule, N-methylmaleimide could be used as protection of the 9,10-positions of anthracene and then removed by FVP. We thought that the maleimide moiety will not be affected in the FC acylation, since the precedencies exist in the literature on imide moiety withstanding the FC

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• detected (Figure 1b inset). According to previous reports, such a fluorescent quenching indicated the formation of a dimeric structure [67][95], and the electron rich substituents at the imide nitrogen should play an important role [96][97]. For comparison, UV–vis absorption and fluorescence spectra of 2

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• paper, we present for the first time a unique example describing the addition of CSI to a system comprising both independent double bonds and imide functional groups. The mechanism for the addition of CSI to a carbonyl group is explained by theoretical computations. Results and Discussion Our starting

• material was 2-ethyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione (9), which we have synthesized in previous studies [16][17]. Imide 9 was synthesized via the cycloaddition of 3-sulfone to maleic anhydride. The reaction of ethylamine with anhydride 8 in the presence of a toluene/triethylamine mixture (3

• :1) produced imide 9 in 80% yield (Scheme 2). To synthesize a new lactam derivative of isoindole-1,3-dione, we investigated the reaction of imide 9 with CSI in toluene at room temperature. Nevertheless, the starting imide 9 did not react with CSI, and we could not obtain the expected products lactam

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• to substitute the S atom and form adduct A. Adduct A underwent a decomposition by releasing a molecule of compound 2 [18]. The formed compound B underwent intramolecular cyclization followed by hydrolysis of the imide group with subsequent decarboxylation and formation of the intermediate C that was

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• (2S,3R,4S)-4 and (2R,3R,4S)-4. To secure the (3R,4R) and (3S,4S) configurations in 3,4-hydroxyglutamic acids enantioselective reduction of the carbonyl group of the cyclic imide (3R*,4S*)-110 prepared from meso-tartaric acid [108] needs to be elaborated (Scheme 27) [109]. Low temperature reduction of

• this imide with a reagent obtained from (R)-binaphthol [(R)-BINAL-H] followed by acetylation furnished the triacetate (3R,4S)-111 as a single diastereoisomer after chromatographic purification (Scheme 27). However, its cyanation as described earlier gave a 38:62 mixture of diacetates (3R,4R,5S)-112 and

• (2S,3R)-2 via Sharpless epoxidation. Reagents and conditions: a) TBHP, D-(−)-DIPT, Ti(OiPr)4, MS, CH2Cl2; b) t-BuMe2SiCl, imidazole, DMAP, DMF; c) NaIO4, RuO2, AcOEt/H2O. Synthesis of (2S,3S)-2 from the imide 51. Reagents and conditions: a) NaBH4, MeOH/CH2Cl2; b) Ac2O, pyridinium perchlorate; c) furan

Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Mikhail A. Syroeshkin,
• Alexander A. Korlyukov,
• Pavel V. Dorovatovskii,
• Yan V. Zubavichus,
• Gennady I. Nikishin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2018, 14, 2146–2155, doi:10.3762/bjoc.14.188

• the examined hypervalent iodine oxidants (PIDA, PIFA, IBX, DMP) PhI(OAc)2 proved to be the most effective; yields of iodo-oxyimides are 34–91%. A plausible reaction pathway includes the addition of an imide-N-oxyl radical to the double C=C bond and trapping of the resultant benzylic radical by iodine

• . It was shown that the iodine atom in the prepared iodo-oxyimides can be substituted by various nucleophiles. Keywords: free radicals; hypervalent iodine; imide-N-oxyl radicals; iodination; N-hydroxyimides; oxidative functionalization; Introduction The presented work opens a new chapter in the

• chemistry of N-hydroxyimides in combination with hypervalent iodine compounds with formation of imide-N-oxyl radicals. These radicals were used as reagents for the addition to a terminal position of the double bond of styrenes with subsequent iodination of the resulting benzylic radical. It is important to

Imide arylation with aryl(TMP)iodonium tosylates

• Souradeep Basu,
• Alexander H. Sandtorv and
• David R. Stuart

Beilstein J. Org. Chem. 2018, 14, 1034–1038, doi:10.3762/bjoc.14.90

• -aryl imide derivatives are relatively rare in such compounds. We were surprised by this disparity, but found that a lack of methods to synthesize N-aryl imides may explain their scarcity; this is particularly true relative to other N-aryl compounds. The survey of methods revealed that the dominant

• approach to N-aryl imides is to employ aniline starting materials (Scheme 1b, left), as was done in the synthesis of pentoxazone and related herbicides [2]. The alternative aromatic substitution approach with imide anions (Scheme 1b, right) is hampered by their low nucleophilicity [3]. Therefore

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• ,b or N-trifluoromethylthiosaccharin 43 in the presence of N-methyl-9-mesitylacridinium under visible light irradiation at room temperature. Terminal, internal, and gem-substituted alkenes bearing imide, ester, amide, ketone, aldehyde and electron-rich aryl functional groups were suitable substrates