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

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• determined by the difference between the HOMO level of the donor and the LUMO level of the acceptor, t-Bu-FIDS, with a higher LUMO level than C60, was used to fabricate a solution-processed BHJ OPV device with the donor poly(3-hexylthiophene) (P3HT). For comparison, the two known evaporable fullerenes C60

• crystalline polymer donor PNTz4T [32] was used. Compared with t-Bu-FIDS, t-Bu-FIDO achieved 3.71% PCE with larger JSC and higher VOC. With PNTz4T, t-Bu-FIDS exhibited low performance, with JSC of only 4 mA/cm2. This lower VOC may be attributable to a suboptimal BHJ structure between PNTz4T and t-Bu-FIDS

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines

• Stefan Jopp,
• Franziska Spruner von Mertz,
• Peter Ehlers,
• Alexander Villinger and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1246–1255, doi:10.3762/bjoc.20.107

• of 12a and 12c are identical which suggests that the strong acceptor groups of 12c do not have an impact on the emission. On the other hand, the strong donor groups of 12e cause a redshift of 0.20 eV as compared to the simple phenyl-substituted molecule. Electron-acceptor groups usually have a

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

• process, an electron is transferred from the HOMO of an arylamine donor to the LUMO of the SeO2 acceptor. The computed HOMO–LUMO energy difference (∆E) between arylamines and SeO2 decreased in the following order: o-anisidine − SeO2 > aniline − SeO2 > methyl anthranilate − SeO2. It revealed that the HOMO

• of methyl anthranilate was relatively buried, with a large energy gap (mismatch) between the donor and acceptor orbitals, which slowed down the oxidative polymerization process and allowed the alternative reaction pathway, electrophilic substitution of SeO2 on the aryl ring. This result was further

• arylamine reactivity. The NBO analysis was carried out using the same basis set, B3LYP/6-31G(d,p). The natural charge (q) of the nitrogen atom, occupancy of the nitrogen lone pair orbital, second-order perturbation energy (E) for intramolecular donor–acceptor interactions, and the donation of electron

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• the transition state was ascribed to the donor–acceptor interactions between the HOMO of the silylene and the LUMO of ethylene, and vice versa [42]. For 2a, the LUMO is largely distributed at the e' bonds, followed by the cis-2 and trans-3 bonds (Figure 8). These results suggest that the formation of

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• ). With the optimized conditions in hand, we explored the substrate scope (Figure 3). In general, substrates with electron donor groups provided a better yield when compared to those obtained with electroneutral or electron-withdrawing groups. Particularly for substrates 9ai,fc,gc, there was no formation

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• friendly and atom-economical process for C–C and C–N bond formations utilizing alcohol as an alkylating agent and hydrogen donor, producing water as the only side-product [6][7][8][9]. Notably, alcohols are inexpensive, abundant and can be obtained from biomass, which makes this method even more attractive

• mol % t-BuOK, t-AmOH, argon atmosphere), various substituted ketones were selectively alkylated with benzyl alcohols as alkyl source and hydrogen donor at 140 °C for 24 h and afforded up to 98% yield of the C-alkylated products (Scheme 26). In addition, numerous substituted benzylic, aliphatic, and

• step, the hydrogenation of the formed intermediate took place via the outer sphere mechanism to deliver the desired alkylated nitrile products (Scheme 54). In 2019, Rueping and El-Seplegy reported the well-defined manganese-PNP complex-catalyzed alkylation of nitriles with alcohols as a hydrogen donor

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• * level of theory (depicted in Figure 4 and Figure 5). Figure 4 reveals that the HOMOs of 1a–7a are predominantly localized on the π-donor units, such as benzene and naphthalene, with an illustration in the case of 6a. On the contrary, the LUMOs are delocalized across the entire π-systems, while also

• 3a in comparison to other compounds within the DCPQ family of compounds. As shown in Figure 5 and Table 1, the donor–acceptor character of the H-bonding counterparts is considerably muted and the HOMO and LUMO in these cases are both relatively delocalized. The HOMO energies of DPQD 1b–7b are also

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• ). The products 5a–t were obtained in 95 to 25% yields, with an average yield of 56%. Furthermore, the method was shown to be highly tolerant towards different functional groups and their combinations. A higher yield tended to be observed when a donor group was located on the arylalkyne at the 6-position

• (5k, 5l, 5r). However, this effect seems to be neutralized when using an electron-rich arylboronic acid (5m). Lower yields are obtained when an acceptor group is present on the arylalkyne (5p, 5q). This leads to the suggestion that an electron-donor group activates and an electron-withdrawing group

• deactivates the compound for the subsequent Suzuki reaction. Furthermore, lower yields were generally observed when a strong electron-donor or -acceptor was attached to the phenyl group at position 5. Higher yields could be obtained by reducing the steric hindrance at position 5 by introducing a 5-membered

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• be generated in situ through the reaction of "reactive" chlorides with a proton donor. For instance, the reaction of acetyl chloride with ethanol is exothermic, accompanied by vigorous HCl gas evolution. It is crucial to emphasize that HCl solutions in MeOH, produced from AcCl and MeOH, pose

• reported. In surface-mediated reactions, the proton donor is typically Si–OH or Al–OH. For clarity in discussing subsequent reactions, we have separated the in situ HCl gas synthesis from the hydrochlorination. It is important to note that these reactions are one-pot processes rather than two-pot reactions

• DHB as a hydride donor and thus give the fully reduced product 142. However, when both DHB and TosCl were present, the reaction of the radical with TosCl was significantly faster leading to 143 in 92% yield. In 2012, Boger demonstrated the efficiency of iron(III) catalysts for the hydrochlorination of

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• generate a large quantity of iodanyl radical from Ts-ABZ (3) homolysis and from the addition–elimination on Ph-EBX (2). Since no quencher is present in the mixture, we wondered if the accumulation of those radicals could be responsible for the low yields obtained. Addition of (TMS)3SiH, a H• donor

• , suppressed the reaction by reducing Ph­EBX (2) (Table 1, entry 6). Using diisopropyl ether as a milder donor had no effect on the reaction (Table 1, entry 7). Next, we tested reducing agents expected to react with the iodanyl radical. The addition of ʟ-ascorbic acid led to no improvement of yield and

• Hantzsch ester suppressed the formation of the desired product (Table 1, entries 8 and 9). Carrying out the reaction in the presence of sodium formate, which can play a dual role of H• donor and reductant [48][49], only led to a decreased of Ph-EBX (2) conversion, along with a diminished yield (Table 1