Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• important factors, and the commonly utilized chemicals include thiols [16][17][18], disulfides [19][20][21][22], sulfenyl halides [23][24][25], sulfonamides [26], sulfenate esters [27][28], and methyl(bismethylthio)sulfonium salts [29][30]. Among various organic molecules, aryl sulfides are recognized as

• succeeded in synthesizing various diaryl(alkyl) sulfides 5 through the sulfenylation of unactivated arenes 4 with an electrophilic sulfur reagent in the presence of a palladium catalyst (Scheme 3) [45]. In the second phase, dibenzothiophene derivatives 6 were obtained via subsequent intramolecular arylation

• of aryl sulfides by using the catalyst and the base. A catalytic cycle is shown in Scheme 4. Firstly, electrophilic Pd(TFA)2 generated from Pd(OAc)2 and TFA, which (by C–H functionalization of arene 4) led to intermediate II. Oxidative insertion of intermediate II into the N–S bond of 1 afforded

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• sulfides, or a separate deprotonation event can also result in similar behavior. Gimeno et al. highlighted this when they designed novel benzimidazole (BIH) donors for the photoreduction with [Cu(dipp)2]2+ photocatalysts [29][30]. They contrasted their work to a previous study by Cunningham and McMillin

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• of heteroatoms, making them a promising alternative to traditional oxidants in the chemical industry [9]. Our interest in sustainable oxidation methodologies led us to study the selective oxidation of various heteroatoms to their corresponding oxides, including sulfides to sulfoxides, phosphine to

• comparative study between the electrochemical and the photoredox pathway, using the exact same chemical matrix, is not yet described. Intrigued by this, we decided to investigate the oxidation of sulfides both via electrochemistry and photoredox catalysis using thioanisole as benchmark substrate. Initially

• in only 20 minutes. Scope Based on the obtained knowledge to optimize the reaction conditions, a variety of sulfides were tested. As shown in Scheme 3, the anticipated products were obtained in good to excellent yields with a few exceptions (2v–z). In general, heteroatoms at the benzylic position (2a

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• a 2:1 ratio with oxabenzonorbornadienes 30 to prevent multiarylated products from being formed. Arylphosphine sulfides were also investigated but gave unimpressive yields (8%); however, upon a substitution of the AgOAc for 3 equiv of AcOH moderate yields were obtained (39%). Mechanistically, this

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• 1,4-dithianes and 1,4-dithiins (1,4-dithiin-1,1,4,4-tetraoxides), it should be noted that the dimethyl derivative 9 has actually been commercialized as the defoliating herbicide dimethipin [32]. Other 1,4-dithiin tetraoxides can be easily derived from the corresponding sulfides by treatment with an

• reported for vinyl sulfides, including dihydrodithiin 13 (Scheme 5a) [36]. In fact, Parham has found that fully unsaturated dithiins can undergo this electrophilic formylation, but at the same time also undergo a ring contraction and an aromatizing desulfurization to yield thiophenes as the main formylated

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

• reoxidized to the disulfide by (NH4)2S2O8. The disulfide (SPyf)2 is also consumed in the thiolation of C-centered radicals affording the SPyf radical and target sulfides, which are in turn useful C-centered radical precursors for photoredox-catalyzed reactions [123]. The high efficiency of the thiolation

• . Electrochemical benzylic oxidation mediated by triarylimidazoles. Thiyl radical-catalyzed CH-arylation of allylic substrates by aryl cyanides. Synthesis of redox-active alkyl tetrafluoropyridinyl sulfides by unactivated C–H bond cleavage by tetrafluoropyridinyl thiyl radicals (SPyf). Main intermediates in quinone

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• synthesis of 1,2-azaphospholidine and 1,2-azaphospholine 2-oxides/sulfides and their fused derivatives. Keywords: azaphospholidine; azaphospholine; phosphonolactam; γ-phosphonolactam; phosphinolactam; γ-phosphinolactam; γ-phostam; Introduction Phosphaheterocycles are a class of important organic compounds

• -azaphospholidine and 1,2-azaphospholine rings (Figure 2). This review includes the synthesis of 1,2-azaphospholidine and 1,2-azaphospholine 2-oxides/sulfides and their fused derivatives. Review Synthesis of 1,2-azaphospholidine 2-oxide derivatives via cyclization Various cyclization strategies have been developed

• for the synthesis of 1,2-azaphospholidine 2-oxides/sulfides and their fused derivatives. The 1,2-azaphospholidine 2-oxide/sulfide derivatives have been prepared by construction of any of their ring bonds. Synthesis via C–N bond formation In 1962, Helferich and Curtius reported the first synthesis of a

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

• sulfides bearing various electron-withdrawing groups at the α-position (Scheme 1) [19][20][21]. Furthermore, we also succeeded in the electrochemical gem-difluorodesulfurization of dithioacetals and dithiocarbonate (Scheme 2 and Scheme 3) [22][23]. In this work, we have studied the electrochemical

• ; (b) o-phthalonitrile (4 mM), and (c) o-phthalonitrile (4 mM) + 1 (8 mM). Scan rate: 100 mV/s. Electrochemical gem-difluorination of sulfides bearing α-electron-withdrawing groups. Electrochemical gem-difluorodesulfurization of dithioacetals. Electrochemical gem-difluorodesulfurization of

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• -aminopyrazoles 5 with very similar EC50 values of about 0.5 μM are representatives of the different classes of compounds: 3,4-dihydroisoquinoline 5g, 4-fluorophenylpiperazine 5k, and isoxazole 5o. Furthermore, among the sulfides 9, the 4-chlorophenylthiopyrazole 9e stands out with an EC50 of 0.2 ± 0.04 µM

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• synergistic cooperation of three catalytic cycles of photoredox, nickel, and HAT catalysis (Figure 12). The HAT-metallaphotoredox process selectively alkylates α-C–H of amines 6, ethers 9, and sulfides 28 with a variety of alkyl bromides 40 (Scheme 23). The Hashmi group further developed the photoredox nickel

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• -atom (80, Scheme 9b) [66]. A similar protocol was adopted by van de Watering in their recent syntheses [67][68]. Sulfides The C2 tethering of indoles with sulfur can be achieved in neutral medium by treatment with various SL2 (L is a leaving group) moieties [69][70]. This is a common method for the

• synthesis of bis(indol-2-yl)sulfides which are the precursors of potent bioactive molecules [71][72][73]. The simple synthetic strategies for the molecular units 82 were first reported by Barbier in 1989. The condensation of tryptamine monoacetate (81a) or indole oxime (81b) with sulfur dichloride in a

• for accessing bis(indolyl)sulfides. To synthesize the unsymmetrical bis(indolyl)sulfide 88, Janosik reacted the indole disulfide 87 with free indole and obtained the product 88 in 81% yield, where the sulfur linkages were 2,3’- with respect to the two indole nuclei (Scheme 11a) [73][74][75][76]. Hall

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

• , olefins, silyl enol ethers, vinyl acetates, sulfides and so on, under mild conditions with high selectivity and yields [29][30][31][32]. All these reactions could be carried out routinely using standard glassware in normal laboratory environments and without any specialist training. Some interesting

• ], electron-rich alkenes (entry 3) [65][66], alkyl sulfides (entry 4) [65][67], 1,3-dicarbonyl compounds [65][68], phosphonate esters (entry 5) [65], steroidal silyl enol ethers and enol acetates (entry 6) [65], pyrimidine bases and nucleosides (entry 7) [67][69], phenylalkynes (entry 8) [70], anthraquinones

• the fluorination of reactive carbanions and easily oxidizable sulfides, whereas the most powerful 18-2h was suitable for less-reactive substrates such as olefins, aromatics, and neutral active methylene compounds. N-Fluoro-6-(trifluoromethyl)pyridinium-2-sulfonate (18-2f’) was prepared later [77]. As

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• sufficient. The reaction tolerated (hetero)aryl and aliphatic tosyl hydrazones as radical acceptors and a variety of olefins with different electronic natures as nucleophilic partners (i.e., vinyl ethers, sulfides, and acetamides). One example of the synthesis of a quaternary center was reported by the

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

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• sativum; allyl sulfides; 3-(dimethylsulfonio)propanoate; Roseobacter; volatiles; Introduction The name of the allyl group has been introduced by Wertheim in 1844 when he investigated the constituents of garlic oil and derives from the botanical name of garlic (Allium sativum) [1]. During that time, the

• ). Total ion chromatograms of CLSA extracts obtained from the feeding experiments with AllMSP fed to A) P. inhibens, B) D. shibae, and C) O. indolifex. Numbers at peaks refer to compounds in Figure 1. Peaks without numbers are unidentified. Volatile allyl sulfides. A) Compounds known from garlic oil, B

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

• to their work on the nitrogen counterparts (vide supra), Fuchigami et al. were successful in the electrochemical production of sulfur-stabilized α-(trifluoromethyl)carbenium ions [139][141]. Thereby, they converted sulfides 213a–h into thioacetals 204a–h (Scheme 52). It is worth to note that the

• presence of an aromatic substituent on the sulfur atom is essential for the sulfides to react. Also, lengthening the perfluoroalkyl chain from CF3 to C2F5 or C3F7 resulted in a significant drop in the yield. Interestingly, while the electrochemical acetoxylation of 213a furnished 204a in an excellent yield

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

• sulfides by the acetamidosulfenylation of alkenes [12], among others [13][14][15]. Sulfur-containing compounds are important intermediates in organic synthesis, being able to act as an electrophile or nucleophile in many organic transformations [16][17][18]. Still, many of them are pharmacologically active

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• on pillararene is a relatively new field, and only a few examples have been reported [53][54]. Wen and co-workers reported the selective photocatalytic oxidation of sulfides in the presence of conjugated macrocycle polymers (COP) with pillar[5]arene struts (Figure 17) [55]. The host–guest

• sulfide substrates and enhances the approximation of the activated oxygen species to the bonded sulfides. Consequently, the oxidation rate of S-1 is accelerated. In the system COP-1, however, no selective binding exists, so that the activity towards both S-1 and S-2 was similar. Diao and co-workers

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• synthesis of benzothiophenes, however, these methods rely on the use of organosulfur-based substrates [38][39][40][41]. Moreover, these methods are associated with some limitations such as using costly metal catalysts, air-sensitive starting materials, malodorous sulfides or thiols, low yields, and

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• disulfides, sulfides or even thiols [167]. However, their use in organophotocatalysis is scarce. In substoichiometric quantities, they are efficient H atom shuttles and play a primordial role in hydrogen transfer mechanisms. For this reason, one of their major applications is the HAT to the cocatalyst

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• chemical quenching leading to the formation of covalent products [67]. Sulfur oxidation: One of the first examples reported for heteroatom oxidation by singlet oxygen was the oxidation of sulfides to sulfoxides [67]. Sulfoxides are important intermediates in organic synthesis, and with applications in

• suggested to give the oxidized product, including the quenching with a second molecule of sulfide (Scheme 44) [67][95][96]. Recent advances have also been achieved using photostable porphyrins and/or heterogeneous catalysts. Mojarrad and Zakavi reported that the oxidation of sulfides using diprotonated

• sulfides to sulfoxides via oxidation by singlet oxygen [97]. A series of sulfides was oxidized to the corresponding sulfoxides in 87–94% yields using only 0.05 mol % of the photocatalyst (TON: 1880) (Scheme 46). The controlled oxidation of sulfides to sulfoxides by singlet oxygen was also reported using

Cascade trifluoromethylthiolation and cyclization of N-[(3-aryl)propioloyl]indoles

• Ming-Xi Bi,
• Shuai Liu,
• Yangen Huang,
• Xiu-Hua Xu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2020, 16, 657–662, doi:10.3762/bjoc.16.62

• and agrochemical industries [3][4][5]. Traditional methods to access these compounds mainly include halogen–fluorine exchange of halomethyl sulfides and trifluoromethylation of sulfur-containing compounds [6][7][8]. Over the last decade, tremendous efforts have been triggered to develop methods for

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• [38][39], dithiols [38], and mercapto benzazoles [40]. These are the first examples of a nucleophilic attack at the selenium atom of the seleniranium cation 2 with the generation of a new Se–S bond, yielding new families of linear unsaturated (Z)-2-[(organylsulfanyl)selanyl]ethenyl vinyl sulfides

• 3. Unusual regio- and stereoselective nucleophilic reactions of thiaselenole 1 at two centers of the seleniranium cation 2. Reactions of thiaselenole 1 with С- and S-centered nucleophiles affording new families of linear unsaturated (Z)-2-[(organylsulfanyl)selanyl]ethenyl vinyl sulfides [31][37][38