Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• likely by nucleophilic aromatic substitution during aqueous workup. Interestingly, electron-donor groups, such as N,N-dimethylamino, proved to be beneficial in terms of yield when they are located at the alkyne-linked aryl group (Scheme 4a). In contrast, the N,N-dimethylanilino group is disadvantageous

• , the presence of N,N-dimethylamino groups leads to strongly enhanced quantum yields up to 71%. The highest quantum yield is observed for 5d (71%), followed by 5f with 51%. However, the presence of a pair of donor and acceptor groups appears to be disadvantageous in terms of quantum yield and the

• presence of only one donor group is advantageous. Interestingly, the quantum yields of 5a (12%), 5g (13%), 5h (8%), and 5i (3%) are comparatively lower than in case of 5g and 5f. It is reasonable to assume that this large difference is caused by the chosen substitution pattern and can be used for further

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• fluorinated diphenylacetylenes and photoluminescence (PL) color in their crystalline states. (a) PL spectra of the donor–π–acceptor (D–π–A)-type diphenylacetylene compounds 1a–g contained in a poly(methyl methacrylate) (PMMA) dispersion film. (b) Photographs of the PMMA dispersion films under ultraviolet (UV

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• in a Mannich reaction [4]. In 2018, our group showed in a proof-of-principle study [5] that the Lewis acid catalysis by DAI salts is based on halogen bonding (XB), an interaction between a Lewis base (XB acceptor) and an electrophilic halogen atom in the Lewis acid (XB donor) [6][7][8][9][10]. In

• abstractions, e.g. to activate gold chloride complexes [18][19]. Therefore, besides the development of new bidentate catalyst motifs, we were still interested in the optimization of these “simpler” derivatives. Thus, we designed a new catalyst motif [20] featuring an isoxazole ring, XB donor 7Z, and compared

• = 10.9139(1) Å, c = 24.3668(3) Å, β = 95.601(1)°) and a density of 2.01865 g/cm3. Two units of the cationic XB donor form a dimer, which is bridged via two bromide ions (Figure 2). As usual for DAI salts, two XB axes are found on the elongations of the C–I bonds. On the one trans to the isoxazolium unit

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• 78 with a pending 4-pyrenyl group. The catalyst acts as H-bond donor but additionally it controls the chiral environment through π-stacking interaction with the aryl group of the substrate, blocking one of the enantiofaces of the iminium intermediate 79. The reaction proceeds in Et2O at −50 °C and

• . In the optimisation of the catalyst 78 structure, several important observations were made (Scheme 19). Replacing thiourea (91) as the H-bond donor unit with squaramide (93) or urea (92) did not affect the enantioselectivity of the allylation of the benzaldehyde-derived acetal. On the other hand

• ] exploited the application of hydrogen-bond donor catalysis in asymmetric dearomative α-allylations of in situ-generated Ν-acylquinolinium salts 108 generated with 2,2,2-trichloroethyl chloroformate (TrocCl) (Scheme 22). Screening through a range of catalysts including the known squaramide and thiourea

Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system

• Yuri A. Sidunets,
• Valeriya G. Melekhina and
• Leonid L. Fershtat

Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200

• derivatives bearing both aromatic and aliphatic substituents. The NO-donor ability of the synthesized furoxano[3,4-d][1,2,3]triazin-7(6H)-ones was additionally evaluated. The elaborated method provides access to novel nitrogen heterocyclic compounds with potential applications as drug candidates or

• a 1,2,3-triazin-4-one core. The proposed method is based on tandem diazotization/azo coupling reactions of the corresponding amides (Scheme 1). In addition, application perspectives of thus prepared heterocyclic entities as thermally stable components of functional organic materials or NO-donor drug

• reagent detects nitrite formed by the enzymatic oxidation of NO) [44][45]. As shown in Figure 3, compounds 1a–e containing an aryl substituent at position 6 exhibited low NO-donor ability (0.3–4.5%). In contrast, compounds 1f–h with an aliphatic fragment showed moderate activity, with the maximum value

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• -type catalysts and more than one million double hydrogen bond donor catalysts. While this repository does not provide any reactivity data, it still comprises a valuable map of organocatalyst chemical space to aid in catalyst design. The creation of these larger datasets, both experimental and in silico

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• on the metabolism [6]. Furthermore, protein synthesis takes only a few hours [7], making the process very fast compared to heterologous expression. CFPS relies on the transcription and translation (TX-TL) system of the donor organism [8]. In addition, the reaction solution contains the DNA-template

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

• ), organogels, molecular wires, self-assembly and so forth [14][15][16][17][18][19][20][21][22][23][24][25]. Moreover, nowadays these invaluable compounds have also received great attention of supramolecular chemists, and finds applications in sensing, catalysis, donor–acceptor systems, energy transfer and

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• coordination of the magnesium ions and subsequent hydrazine inactivation. The diversity-oriented nature of this consecutive four-component synthesis was used to synthesize 17 different donor/acceptor-substituted pyrazoles 108 in moderate to good yields (Scheme 39) [136]. The synthesis of bispyrazoles was also

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

• Deepa Nair,
• Abhishek Tiwari,
• Banamali Laha and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177

• reactions, especially as a Michael donor at the central methylene carbon, and Michael acceptor at the enone vinyl carbon. Therefore, it would be interesting to develop novel methodologies using curcumin and its non-natural analogs as key starting materials [24]. Because of its multifaceted reactive site

• , curcumin showcases its Michael donor–acceptor ability in different ways, such as simple Michael addition, [4 + 2] annulation, Michael addition followed by cyclization or one-pot multicomponent reactions (MCR), etc. (Scheme 1) [25]. In 2011, our group reported the reactivity of curcumin as a Michael donor

• ]. Other groups have also investigated the Michael donor–acceptor reactivity of curcumins [25]. For instance, a quinine-thiourea catalyzed Michael addition of curcumins to nitroalkenes reported by Ye et al. stopped at the single Michael addition stage [35]. In the subsequent year, Yan et al. demonstrated a

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• electron donor to furnish the olefin product 148. In the cathodic chamber, reduction of the acidic proton of TFA counterbalance the overall transformation. A wide range of carbonyl compounds including aromatic and aliphatic aldehydes and ketones as well as various alkene partners were compatible. Of note

Development of a flow photochemical process for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence: in situ-generated 2-benzopyrylium as photoredox catalyst and reactive intermediate

• Masahiro Terada,
• Zen Iwasaki,
• Ryohei Yazaki,
• Shigenobu Umemiya and
• Jun Kikuchi

Beilstein J. Org. Chem. 2024, 20, 1973–1980, doi:10.3762/bjoc.20.173

• benzyltrimethylsilane derivatives as the donor molecule in the flow photoreactor to provide 1H-isochromene derivatives in higher yields in most cases than the batch reaction system. Keywords: 2-benzopyrylium; flow chemistry; isocromene; photochemical reaction; π-Lewis acidic metal; Introduction Flow chemistry has

• intramolecular cyclization followed by proto-demetalation with trifluoroacetic acid (TFA). In catalytic cycle II, photoexcitation of the generated 2-benzopyrylium intermediates A under light irradiation facilitates single-electron transfer (SET) from benzyltrimethylsilane derivatives 2 as the donor molecule

• afforded the product 3r in high yield when the temperature of the premixing zone was increased to 50 °C (Table 3, entry 7: 73%). The scope of donor molecules 2b and 2c having an electron-withdrawing trifluoromethyl group and an electron-donating methoxy group [60][61] at the para-position of the

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• substrate 1c may act as an electrophilic center, forming a C–O bond with the alkenyl group to give the isochromen-1-one oxime product 2c'. When wet HFIP was used as the solvent, the reaction followed a different pathway. HFIP, a strong hydrogen bonding donor [26][27][28], interacts with the amide moiety of

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• compounds. Dömling et al. [50] also reported the synthesis of N-edited guanine derivatives. Different drugs display the guanine motif, fundamental for its biological activity is a triad HBA–HBD–HBD (HBA = hydrogen bond acceptor, HBD = hydrogen bond donor) included in its structure. The authors propose a one

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• high substrate flexibility. SAM is the universal methyl donor of biological methylation reactions, and it is the main outcome of the methionine cycle. Following transfer of the methyl group, SAH is formed, which is then hydrolysed to ʟ-homocysteine and adenosine by an SAH hydrolase. ʟ-Homocysteine is

• remethylated to ʟ-methionine by the enzyme methionine synthase, which utilises 5-methyltetrahydrolate (5-MTHF) as a methyl donor. 5-MTHF is a constituent of the folate cycle, which encompasses the intermediates tetrahydrofolate (THF) and 5,10-methylene-THF (5,10-CH2-THF). 5,10-CH2-THF is formed from THF and ʟ

• -serine, which provides the methyl group in this case. Another methyl donor that provides a C1 building block for ʟ-methionine and subsequent SAM synthesis is betaine. Betaine-homocysteine MT remethylates ʟ-homocysteine to ʟ-methionine. Non-SAM-dependent MTs catalyse B12-dependent methylations using the

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• bisphosphonic acids as dopants in Nafion membranes that led to an increase on the proton conduction of the new membranes, since these compounds are good proton carriers due to their proton donor and acceptor behavior [26][27][28][29]. In addition, the increase in the proton conduction of the doped membranes has

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• partition coefficient logarithm (log P), H-bond acceptor/donor count (HAcc/HDon), fraction of sp3-hybrid carbon atoms (F(sp3)), and rotatable bond count (RotB) are shown in Figure 5. It is apparent that the GBB chemical space contains many drug-like (69,043,101 molecules, 25%) and “beyond-Ro5” compounds (75

• performance in the parallel GBB reaction. (Hetero)aromatic aldehydes 2{1–6} illustrating electronic and steric effects on the parallel GBB reaction. Physicochemical properties of the chemical space of 271 Mln. members obtained by virtual GBB reaction (MW – molecular weight; HAcc/HDon – H-bond acceptor/donor

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• UV light, we have previously reported a design of amphiphilic donor–acceptor Stenhouse adducts (DASAs) controlled by white light. Herein, we present a series of DASA amphiphiles (DAs) with minor structural modifications on the alkyl linker chain length connecting the DASA motif with the hydrophilic

• fabrication of visible-light-controlled macroscopic scaffolds, offering the next generation of biomedical materials with visible-light-controlled microenvironments and future soft-robotic systems. Keywords: donor–acceptor Stenhouse adduct; photoresponsive molecular amphiphile; supramolecular transformation

• , stiff-stilbene [26], azobenzene [27][28], molecular motors [19][29][30], spiropyran [31][32][33], indigo [34][35], and donor–acceptor Stenhouse adducts (DASAs) [36][37], have been used in supramolecular systems for photoswitchable smart electronic, optoelectronic, and biomedical materials [30][38][39

Bioinformatic prediction of the stereoselectivity of modular polyketide synthase: an update of the sequence motifs in ketoreductase domain

• Changjun Xiang,
• Shunyu Yao,
• Ruoyu Wang and
• Lihan Zhang

Beilstein J. Org. Chem. 2024, 20, 1476–1485, doi:10.3762/bjoc.20.131

• possessed Q at this residue. This substitution can be reasonable, as it serves as a hydrogen bond donor to activate the β-keto moiety of a substrate [31][32]. Additionally, the presence of K (4), which activates the catalytic tyrosine, was more conserved in C2-type KRs. In general, C2-KRs show similarity to

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• transformation (Table 1, entries 2–5). Thiourea, which is regarded as a classic H-bond donor in carbonyl activation, also could not boost the yield (Table 1, entry 6). Fortunately, it was found that the yield of 4aa was gradually increased to 64% upon adding 3a from 2.0 to 10.0 equiv (Table 1, entries 7 and 8

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• halogen-bond formation by the linear combination of the % p-orbital character on the halogen and energy of the σ-hole on the halogen-bond donor. Keywords: aryl halide; diarylhalonium; halogen; halogen bond; non-covalent interaction; Introduction Halogen bonding has emerged as an important attractive

• engage in halogen-bonding interactions [29][30]. In this work, a series of halogen-bond donor molecules and their halogen bond complexes with chloride anion were optimized at the M062x/6-311+G(d) level of theory [31] with def2-tzvpp used for iodine and astatine, and with SMD solvation in tetrahydrofuran

• contacts (Scheme 3). The monovalent halogen-bond donors of phenyl, mesityl, and pentafluorophenyl derivatives 25–35 had endergonic association with chloride (Scheme 3). Pentafluorophenyl astitide (36) was the only neutral monovalent halogen-bond donor with an exergonic association with chloride (ΔG = −5.0

Synthesis of cyclic β-1,6-oligosaccharides from glucosamine monomers by electrochemical polyglycosylation

• Md Azadur Rahman,
• Hirofumi Endo,
• Takashi Yamamoto,
• Shoma Okushiba,
• Norihiko Sasaki and
• Toshiki Nokami

Beilstein J. Org. Chem. 2024, 20, 1421–1427, doi:10.3762/bjoc.20.124

• effect. Although glycosyl donors with an N3 group in position C-2 have been used for α-selective glycosylation [20][21], we have already found that β-selective glycosylation proceeds using a glycosyl donor with an N3 group under electrochemical conditions [22]. The results of the electrochemical

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

• catalyst is first excited and then transfers one electron to the thiocarbamate moiety to form a thiocarbamate radical anion, with change in oxidation state from III to IV. Next, the sacrificial electron donor Hünig base successfully converts [Ir(IV)] to [Ir(III)], with concurrent formation of an amine

• electron density, which facilitates a π–π interactions with the aryl iodide system and ultimately results in the production of an electron donor–acceptor (EDA) complex 21. Photoexcitation of this EDA complex furnishes an aryl iodide radical anion and a radical cation complex 22. Then, the elimination of

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• prepare an array of target 1,2,3-triazoles 4 with allomaltol unit (Scheme 4). It is interesting to note that the recyclization products can be synthesized in good yields employing various starting arylhydrazones 3 both with donor and acceptor substituents at aromatic rings. Besides that, heterocyclic

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

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

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• a hydride donor [5][6][7][8]. On the other hand, aryl radical-involved hydroarylation would be a promising alternative for the synthesis of alkylarenes with high anti-Markovnikov selectivity [9][10]. Aryl halides have received increased attention as ideal radical precursors because of their