Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• 350–352 in good yields via benzyne intermediate 353 followed by a [2 + 2] cycloaddition with the sulfoxide affording an o-quinone intermediate 354 (Scheme 78) [132]. Furthermore, dioxolane compounds have also been subjected to synthesize cinnamic acid derivatives through CO2 release. For example, Chen

Total synthesis of (±)-simonsol C using dearomatization as key reaction under acidic conditions

• Xiao-Yang Bi,
• Xiao-Shuai Yang,
• Shan-Shan Chen,
• Jia-Jun Sui,
• Zhao-Nan Cai,
• Yong-Ming Chuan and
• Hong-Bo Qin

Beilstein J. Org. Chem. 2025, 21, 601–606, doi:10.3762/bjoc.21.47

• were optimized to achieve product 20 with 85% yield, minimizing potential side reactions. The subsequent dearomatization step is crucial for the construction of the cyclohexadienone unit. Oxidation of compound 20 with PIDA in trifluoroethanol, the original phenol was converted into a quinone moiety

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• -methylquinazolinones [3], 2-methylbenzoxazinones [4], and 2-methylbenzoxa(thia)zoles [5] the interaction with sterically hindered 1,2-benzoquinones and 3,4,5,6-tetrachloro-1,2-benzoquinone proceeds with the expansion of the o-quinone ring and results in 2-hetaryl-substituted 1,3-tropolones 1 (Scheme 1), which exhibit

• interaction of 2,3,3-trimethylindolenine with 3,5-di(tert-butyl)-1,2-benzoquinone leads to the formation of indolo[1,2-a]indoline derivatives [23], while the presence of a nitro group in 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone the reaction with 2,3,3-trimethylindolenine leads to an o-quinone ring

• contraction and the formation of 2-azabicyclic products and pyridino[1,2-a]benzo[e]indol-10,11-diones [24]. o-Chloranil was found to be the most efficient 1,2-benzoquinone, which engages in o-quinone ring-expansion reactions with 2,3,3-trimethylindolenines to form hard-to-reach polychlorinated derivatives of

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• the natural product, cyanosafracin B (4), bearing a para-quinone moiety at the left end [14]. Considering the relationships between the aromatic ring structures and DNA alkylating ability, we envisioned a modular and flexibly modifiable synthetic approach that would allow for the initial installation

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• esters containing a quaternary stereocenter, and the control of regioselectivity depended on the bulkiness of the substrates. Additionally, the electrochemical system served as an internal syringe pump, generating quinone from hydroquinone in situ through anodic oxidation, which enhanced the

• product 36. Finally, using 1-naphthyl ester and relatively bulkier 2,6-dimethylhydroqunone as starting materials produced chiral 1,6-addition products 37. In mechanistic studies, using quinone 38 instead of hydroquinone 34 in the electrochemical-free process produced the desired product 36, with a similar

• yield but a significantly lower ee (48%) than that obtained under standard electrochemical conditions. By contrast, when quinone was added gradually over 4.5 h using a syringe pump, the desired product 36 was obtained with a similar yield and enantioselectivity. This result corresponded to that of a

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• of an ortho-quinone methide intermediate XXXVII formed through nucleophilic attack of the 2-naphthol to the aldehyde followed by reaction with 1,3-dicarbonyl compound coordinated by the copper. The subsequent intramolecular nucleophilic attack of the oxygen to the enol and water elimination resulted

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• subsequent oxidation with DDQ provided the respective products 127. When indoles 129 were utilized with quinone 128, no further oxidizing reagents were necessary to afford indolylquinones 130. All products were obtained with high enantiomeric ratios and moderate to good yields. A model reaction performed at

• a gram scale gave the product with analogous yield and enantioselectivity (73%, 96% ee). Hydrogen-bond-stabilized axially chiral N-arylquinones 133 were prepared by reaction of quinone esters 131 with anilines 132 mediated by CPA (R)-C23 (Scheme 39) [67]. Apart from respectable yields and remarkable

• conditions were compatible with many substrates containing methyl, methoxy, halogen, and aryl groups, providing excellent enantioselectivies and moderate to high yields. Control experiments indicated an activation mode through the vinylidene ortho-quinone methide (VQM) intermediate as well as the importance

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• the field, other dienes bearing two nitrogen atoms in their structure such as 1,3-azadienes or azo-alkenes are also included. On the contrary, asymmetric cyclizations involving aza-ortho-quinone intermediates and in situ-formed 1-azadienes were excluded as they have been discussed in other recent

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• equiv) as the base in methanol under a nitrogen atmosphere, with 5 W LEDs irradiation for 3 days (Scheme 9). Various substituted quinone N-oxides yielded the corresponding products in satisfactory to moderate yields. Notably, electron-withdrawing groups generated higher yields compared to electron

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• catechol 3. This effect is due to a decrease in the acceptor effect of the thioether group. In turn, the second two-electron stage for 4 is recorded at earlier potential values. On the contrary, this behavior is caused by the presence of CH2-linker which divides electrogenerated quinone form and

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• oxidation-controlled cyclooctyne-1,2-quinone cycloaddition (SPOCQ) was developed and employed in the same fields of chemical biology [6][7]. On the other hand, the use of the SpAAC in materials science was slow. We developed another class of metal-free click chemistry reactions, such as the [2 + 2

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• respective chapters: A quinone structure has been given with the first report of botrallin [36], but was corrected some years later [37]. A wrong constitution has originally been proposed for altenuene [38]; it was revised shortly after [39]. The originally proposed structure [40] of altenuisol is wrong

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• trap the phenoxonium cation formed in the oxidation as an acetal, that later were hydrolysed to the quinone. Formation of hydrogen gas as the cathode reaction caused challenges in the flow cell and were overcome by recycling the reaction mixture through the cell at increased flow rate several times

• properties make them privileged structures in medicinal chemistry [2]. Benzoquinone and naphthoquinone can exist as ortho-quinone and para-quinone, with the latter considered more stable [5]. Additionally, p- and o-quinones are formed in metabolism of drugs [6] as well as polycyclic aromatic hydrocarbons

• (PAHs) by cytochrome P450 (CYP) and other metabolic enzymes [7][8]. Main metabolic pathways form quinone isomers of benzo[a]pyrene [8], naphthalene [9][10], and benzene [11]. Numerous methods for the oxidation of phenols or their derivatives to quinones have been described [12]. Oxidation with Fremy’s

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• photocatalytic mechanism. Photoredox-catalyzed hydroacylation of olefins with aliphatic carboxylic acids. Acylation–aromatization of p-quinone methides using carboxylic acids. Visible-light-induced deoxygenation–defluorination for the synthesis of γ,γ-difluoroallylic ketones. Photochemical hydroacylation of

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• 9 and the quinone derivative 2,5-bis((2-methoxyphenyl)amino)cyclohexa-2,5-diene-1,4-dione (10) were isolated from the mixture. The spectroscopic data were consistent with earlier reports on the direct synthesis of 9 [50][51] and 10 [52]. The mass spectrum of oxamide 9 showed peaks corresponding to

• the sodium complexes [M + Na]+, [2M + Na]+, and [3M + Na]+ (Figure S13, Supporting Information File 1). The mass spectrum of quinone 10 showed a peak for [M + H]+ (Figure S17, Supporting Information File 1). Reaction of methyl anthranilate with SeO2 After observing that unsubstituted aniline and

• latter undergoes addition–elimination reaction with another molecule of o-anisidine to give 2-(phenylamino)cyclohexa-2,5-diene-1,4-dione. The third unit of o-anisidine is added to the quinone via 1,4-addition, followed by oxidation of the 1,4-dihydroxy compound to give 2,5-bis((2-methoxyphenyl)amino

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• cleavage and rearrangement reactions, which are catalyzed by AlpJ-family oxygenases, including AlpJ, JadG, and GilOII. Prior investigations established the essential requirement for FADH2/FMNH2 as cofactors when utilizing the quinone intermediate dehydrorabelomycin as a substrate. In this study, we unveil

• quinone structure. Consequently, we redirected our focus towards alternative, more electron-rich substrates. In a preceding investigation, we identified that the bifunctional enzyme JadH proficiently converted prejadomycin (9) to 8, a compound demonstrated to spontaneously oxidize to 1 under aerobic

• -independent reactions failed to occur. It is plausible that 1 lacked the capability to reductively activate molecular oxygen owing to the quinone structure. In these instances, FADH2/FMNH2 were deemed necessary as cofactors for AlpJ-family oxygenases. These findings uncover a noteworthy substrate-controlled

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• amines, the direction of which is controlled by the large positive charge at the C(2) center of the p-quinone imine moiety of the heterocycle. With this in mind, we turned our attention to solid-state organic reactions. Numerous examples of nucleophilic substitutions at carbon centers are discussed in

• absorption spectral data are given in Table 3. Conclusion The diverse reactions of 3H-phenoxazin-3-one derivatives with nucleophilic reagents are primarily directed toward the p-quinone imine fragment [5][13][15]. In the presence of protonic acids, the reaction with amines proceeds through Schiff base

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• involving a first Friedel–Crafts reaction of aldehyde 3 (oxocarbenium intermediate 7' is also a good candidate for this reaction, see next paragraph) with 1,3,5-trimethoxybenzene (5), leading to intermediate 8 (Scheme 3). This last compound was too reactive to be isolated, presumably leading to a quinone

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• efficient synthesis of spiro[azepine-4,3'-indoline] derivatives via the [4 + 3] cycloaddition reaction of bromo-substituted isatin-derived MBH adducts and N-(o-chloromethyl)arylamides. In this efficient protocol, the reactive allylic phosphonium ylides and aza-o-quinone methides were generated in situ and

• )benzenesulfonamides to give chiral azepane spirooxindoles with excellent stereoselectivity (reaction 2 in Scheme 1) [55][56]. Du and co-workers reported a DABCO-mediated [4 + 3] cycloaddition reaction between o-quinone methides and isatin-derived MBH carbonates to give functionalized benzo[b]oxepine derivatives in

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• quinone unit on quinoxaline to achieve donor–acceptor interactions and desirable electronic properties. The compounds exhibited absorption, emission, electrochemical, and thermal properties suitable for n-type materials. Theoretical properties were also investigated using time-dependent DFT. The HOMO and

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• by various quinone derivatives [63]. For both mechanisms, the first steps are typically rate determining and thus, in general, the rate law is: where k1 and k2 are rate constants for the first steps of the “cleavage first” and “ET-first” pathways respectively, k1 being negligible in the case of

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

• reductive quenching of Ru(bpy)3 and reduction of photooxidized Ru(bpy)3. Furthermore, quinones have well-studied PCET chemistry [26]. 2,3-Dichloro-5,6-cyano-1,4,hydroquinone, the hydrogenated form of 2,3-dichloro-5,6-cyano-1,4-benzoquinone (DDQ), has the highest oxidation potential of the 3 quinone examples

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• (Figure 3c): (i) an uptake of the molecular cargo was firstly accomplished by immersing the metal-organic crystals in a 1.2 M solution of para-benzoquinone in chloroform which leads to the loading of a 9.82% w/w of quinone; (ii) photoirradiation at 312 nm over a period of 8 hours which leads to the

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• , prepared by benzylic bromination of the methyl substituents of 132 and 133 (Scheme 29). 5 1,4-Michael addition Narita et al. [72] reported their total synthesis of bauhinoxepine J (139), a quinone dihydrobenzoxepine derivative, by means of a base-promoted intramolecular etherification (Scheme 30). 6