Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• used for late-stage modification of bioactive compounds, including natural products. These developments will find suitable applications in medicinal chemistry for introducible organosilyl groups (Scheme 5) [55]. A visible-light-induced Friedel–Crafts acylation of arenes and heteroarenes was reported by

• regioselective acylation products, but heteroarene substrates produced a mixture of products, for example, furan, thiophene, and benzothiophene. Compared to the traditional LAs-mediated Friedel–Crafts acylation, the described radical method offers a regiodivergent result with good functional group tolerance. The

• Lewis acid-mediated traditional Friedel–Crafts acylation of 2-methoxynaphthalene typically proceeds at the ortho positions relative to the methoxy group due to the electron-rich nature of these sites, while the meta position remains deactivated under the ionic mechanism. Notably, the present work

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• described above, glycosides 81 were inactive against cancer and melanoma cell lines. 3,3-Diaryloxindole-N-glycosides The Friedel–Crafts acylation of isatin-N-rhamnoside β-16a with benzene (82a) afforded 3,3-diphenyloxindole-N-rhamnoside β-83a in 94% yield (Scheme 44) [63]. Deprotection of the latter

• afforded β-84a in 88% yield. Friedel–Crafts acylation of isatin-N-glycosides β-16c–e with benzene, toluene, anisole, and N,N-dimethylaniline and subsequent deprotection afforded 3,3-diaryloxindole-N-glycosides β-84b–l (Scheme 45) [63]. Some of the products showed antiproliferative activity against

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• reported over the years (Figure 2) [2]. Conventionally, benzophenones are synthesized by Friedel–Crafts acylation of benzoyl halides and aromatic compounds. However, the regioselectivity of Friedel–Crafts benzoylation at the desired position is difficult to control [9]. On the other hand, 2

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• for diverse applications in future studies. Keywords: condensation; co-timerization; dipyrromethane; Friedel–Crafts acylation; heterocycles; pyrrole; truxene; Introduction The scaffold of truxene (10,15‐dihydro‐5H‐diindeno[1,2‐a;1′,2′‐c]fluorene) and its congeners comprises three fluorene subunits

• derivatives (12, 15, and 17) in controlled manner (with appropriate equivalents of acetyl chloride and aluminium chloride) using one-to-threefold Friedel–Crafts acylation reaction(s) at 0 °C to rt in dichloromethane (DCM) solvent (Scheme 1 and Scheme 2). Subsequent condensation of thus prepared acetylated

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• bisorbicillinoid family. Substrate 33 for SorbC-catalyzed enzymatic transformation was synthesized in 3 steps from phenol 35 via formylation and subsequent reduction to introduce a methyl group, followed by a Friedel–Crafts acylation with 36 (Scheme 4B) [39][40]. The in vitro enzymatic transformation of 33 by

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• substituents, respectively, were also attempted but without success. In these cases, the sterically congesting ortho isopropyl and tert-butyl groups stymie the Friedel–Crafts acylation step leading to diketone (Scheme 1). Experimental and computational studies of 1,3-diarylisoacenofurans Purified

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• ], Friedel–Crafts acylation [12], radical cascade reactions [2][13], and photoinduced radical cyclizations [14][15][16][17]. However, these methods often suffer from drawbacks such as harsh reaction conditions and the requirement of transition-metal catalysts. Although photocatalyzed cyclization reactions

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• Swantje Lerch Stefan Fritsch Thomas Strassner Professur für Physikalische Organische Chemie, Technische Universität Dresden, 01062 Dresden, Germany 10.3762/bjoc.19.20 Abstract An iron(III) chloride hexahydrate-catalyzed Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic

• acylation; homogeneous catalysis; ionic liquids; iron catalysis; TAAILs; Introduction The Friedel–Crafts acylation is one of the oldest metal-catalyzed reactions in organic chemistry [1] and allows for the synthesis of a broad range of diverse compounds [2][3][4][5]. Starting from electron-rich aromatic

• proved to be a remarkable class of compounds due to their high thermal and chemical stability, their negligible vapor pressure and high versatility in terms of chemical structure and usage [21][22][23][24]. Successive research for the Friedel–Crafts acylation lead to the development of various reaction

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• 23% overall yield. First, hydrolysis of 1, in situ conversion to the acyl chloride and subsequent Lewis acid-promoted Friedel–Crafts acylation reaction produced compound 2 (Scheme 1), where the AlCl3 was also responsible for the demethylation. Compound 2 was then subjected to monoalkylation with 1,4

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• using polyphosphoric acid [16] and sulfuric acid failed [42], therefore we tried Friedel–Crafts acylation. For that, 27 was hydrolysed to the corresponding diacid 28 with lithium hydroxide [15]. In a manner similar to [24], firstly, a ‘cold’ Friedel–Crafts acylation in dichloromethane was attempted, in

• the ring closure proceeded on one side of the molecule. It was assumed that this species precipitated, preventing further reaction. We thus turned to a ‘hot’ Friedel–Crafts acylation, in which the reaction mixture was refluxed after the addition of oxalyl chloride, followed by removal of the volatiles

• . Since the ring-closure with a ‘hot’ Friedel–Crafts acylation [43] led to an insoluble material, we wanted to synthesise a soluble derivative by attaching 4-(2-ethylhexyl)-2-methylthiophene groups. This was done by reacting intermediate 27 with compound 32, which was prepared as shown in Scheme 3. In a

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• preference for cyclization onto the C5 position is more dominating than the higher nucleophilicity of the C3 position, making the CAr–C bond formation completely regioselective at the C5 position. Subsequently in 2017, Li and co-workers also applied the intramolecular Friedel–Crafts acylation strategy to get

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• activated derivatives (intramolecular Friedel–Crafts acylation) [29][30][31] found wide application here. In a different approach, a total synthesis of dengibsin (1a) was accomplished by Wang and Snieckus in 15 steps by means of a directed remote metalation [32], using a benzamide residue as the directing

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• subsequent reduction of the anthraquinone gave 1,4-difluoroanthracene. After ortho-lithiation and reaction with phthalic anhydride a carboxylic acid was obtained whose Friedel–Crafts acylation and subsequent reductive removal of the oxygen-functionalities resulted in the formation of the target compound. The

• acid precursor could be prepared by reaction of the anthracenyllithium 7 with phthalic anhydride (8). Intermediate 7 could be accessed by ortho-lithiation of anthracene 9. The synthesis of 9 by two consecutive Friedel–Crafts acylation reactions and reduction of the resulting anthraquinone could start

• from 8 and 1,4-difluorobenzene (10). Starting point of the synthesis was the conversion of 1,4-difluorobenzene (10) to 1,4-difluoroanthraquinone (11, Scheme 2) [14]. The first Friedel-Crafts acylation of phthalic anhydride was achieved using AlCl3 in boiling 1,4-difluorobenzene (10). The second Friedel

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• , so it was sought to minimise their exposure to these conditions during synthesis. In the end, we used two routes to the thioindoxyls: either Friedel–Crafts acylation of α-phenylthioacetic acids (which are easily accessible from thiophenols by alkylation using 2-chloroacetic acid, Figure 1b) or else

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• well-established reactions (Scheme 2). The indanone is formed by intramolecular Friedel–Crafts acylation of 2 under microwave radiation as reported by Oliverio et al. [23]. The second step is the demethylation of indanone methyl ether 3 by aluminium trichloride in toluene at reflux [24]. Two indanone

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• initiated. The syntheses of the appropriate azatryptamine derivatives (17, 18, 25, and 26) were achieved from the non-expensive and commercially available 4- and 7-azaindole (13 and 20), respectively. First, 13 and 20 were converted in a Friedel–Crafts acylation with chloroacetyl chloride (ClCH2COCl) and

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• starting from an isoquinoline bearing an ester group at C-8. In a photoredox-catalyzed direct C–H arylation a 4-methoxyphenyl residue from a methoxyphenyldiazonium salt was introduced at C-1, and after ester hydrolysis intramolecular Friedel–Crafts acylation afforded menisporphine (2). In continuation of

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• has been reported that nitration and bromination of 2 take place at the 1-position (however, the bromine atom in 1-bromopyrene can migrate into the 4-position in the presence of AlCl3) [8][9], whereas Friedel–Crafts acylation and Vilsmeier formylation take place at the 4-position [10]. We recently

• whether TfOH-promoted Friedel–Crafts acylation of 2 will also occur at the 1-position. For this purpose, we examined the reaction of 2 with acetic acid and trifluoroacetic anhydride, (TFAA)/TfOH, according to our protocol used for the acylation of pyrene with alkynoic acids [25]. However, in this case we

• sterically hindered pyrene 1-position, whereas the bulkier protonated acetyl trifluoroacetate (the postulated electrophile in the examined Friedel–Crafts acylation) attacks sterically the less hindered 4-position. Conclusion We found that triflic acid-promoted (thio)carbamoylation of 2 with aliphatic iso

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• and one separation step. In the first step, a Friedel–Crafts acylation of isobutylbenzene (1 equiv) and propionyl chloride (1.17 equiv) in the presence of AlCl3 as Lewis acid was carried out in a tubular reactor. The residence time is one minute, and the temperature is maintained at 87 °C. The outlet

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

• reaction of malonic acid with chlorobenzaldehyde [21]. In the first step, the substrates reacted in the presence of formic acid and diethylamine to form 3-chlorophenylpropionic acid followed by a intramolecular Friedel–Crafts acylation with malonyl chloride in the presence of zinc chloride to give 5-chloro

• -arylpropanoic and 4-arylbutanoic acids has been reported in 2015 by Le et al. [22]. The authors applied a microwave-assisted intramolecular Friedel–Crafts acylation catalyzed by metal triflate in triflate-anion containing ionic liquids. This synthesis proceeded with the goals of green chemistry and allowed to

• coelenterazine (luciferin) of which three inhibitors containing an 1-indanone core 33 have been synthesized to follow the bioluminescence reaction mechanism [28]. The intramolecular Friedel–Crafts acylation of 3-arylpropionic acid derivative 31 followed by conversion of the acid to the corresponding acyl

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• heating isatine with malonic acid followed by esterification of the produced quinoline carboxylic acid with methanol in the presence of sulfuric acid at 80 °C for 6 h. 4-Arylphthalazin-1(2H)-ones A7 and A8 [24][25] were prepared by Friedel–Crafts acylation reaction of N-aminophthalimide with either

The digital code driven autonomous synthesis of ibuprofen automated in a 3D-printer-based robot

• Philip J. Kitson,
• Stefan Glatzel and
• Leroy Cronin

Beilstein J. Org. Chem. 2016, 12, 2776–2783, doi:10.3762/bjoc.12.276

• platform is a three-step synthesis of the popular nonsteroidal anti-inflammatory drug ibuprofen ((R,S)-2-(4-(2-methylpropyl)phenyl)propanoic acid) starting from isobutylbenzene and propanoic acid (see Scheme 1). These starting materials undergo a Friedel–Crafts acylation using trifluoromethanesulfonic