Advancements in hydrochlorination of alkenes

• Daniel S. Müller

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

• , HCl gas was bubbled through neat alkene 1 for several hours, as depicted in Scheme 3A [35]. This example highlights an intriguing regioselectivity that might have been challenging to predict through a simple analysis of the stability of the corresponding cations. Alternatively, the HCl gas was bubbled

• dependence. Brown also explored the influence of solvents (Figure 4). While reactions conducted in neat α-methylstyrene (11) or dichloromethane showed identical kinetics, the reaction was delayed when pentane was employed as a solvent. The method of bubbling HCl gas through neat alkenes or solutions of

• alkenes remains a commonly employed approach, yielding high yields for styrene derivatives (Scheme 4) [41][42][43]. The example by Theato is remarkable (Scheme 4A), who used HCl (gas) bubbled into neat alkene 13 for 5 hours, and obtained a relatively high yield of the monohydrochlorinated product 14 after

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• , MeOH); UV (MeOH) λmax, nm (log ε): 281 (2.27), 270 (2.96), 260 (2.40); ECD (100 μg/mL; MeOH), λmax, nm (Δε): 226 (−0.31), 274 (−0.76), 282 (−0.96); IR (neat): 3443, 2965, 2925, 2896, 1646, 1457, 1086 cm−1; HRESIMS (m/z): [M + Na]+ calcd for C44H66O15Na+, 857.4294; found, 857.4294. In vitro

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

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• temperature under neat conditions [73][74][75][76][77]. In order to promote light-induced ring contraction of 1,2-dithiin scaffolds, Furukuwa et al. explored the reactivity of precursors bearing one sulfur atom in a higher oxidation state [78]. In their synthesis of dibenzo[1,4]dithiapentalene 46, the 1,2

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• glycosyl donor) was added under argon followed by neat TfOH (2 μL, 0.02 mmol) to give a persistent iodine color as described previously [36]. The reaction mixture was stirred under argon at −40 °C until complete consumption of the starting thioglycoside (TLC monitoring, Rf 0.68 (1), Rf 0.57 (2), benzene

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• , amphiphiles PA-OCH3 and PA-OH were synthesized by reacting prePA under neat conditions with 1-(2-bromoethoxy)-2-(2-methoxyethoxy)ethane (67% yield over 2 steps after ion-exchange) and 2-[2-(2-chloroethoxy)ethoxy]ethanol (42% yield), respectively (Figure 2b). Imidazole-functionalized amphiphile PA-Im was

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• spectrum) [106], we never detected such a peak in 19F NMR spectra of the neat IL, analysed after reaction work-up, keeping it under vacuum to completely eliminate diethyl ether traces before NMR analysis. It should be mentioned that the solution was kept in the NMR tubes only for the time necessary to

• base and the base–BF3 adduct, we should obtain an approximate current yield. Our first choice was N,N-diisopropylethylamine (DIPEA), as the DIPEA-BF3 adduct is reported in the literature and fully characterized by NMR in CDCl3 [113]. To be consistent with literature data, the BF4− peak in neat BMIm-BF4

• anolyte and the mixture was kept under stirring at room temperature for 30 min. Then, the neat anolyte was analysed by NMR (19F and 13C). The 19F NMR spectrum showed a new peak at −148.7 ppm and, to our great astonishment, we found only one set of signals in the 13C NMR spectrum (55.0, 42.8, 17.4, 16.0

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• . Since the freedom of movements (vibrations and rotations) of parts of REF are prevented in the solid state, the PL spectra of the films of compounds 6–9 were practically in the same spectral region (Figure 2d). It should be noted that the PL spectra of the neat films exhibit low-intensity high-energy

• . Similarly, the strongest TADF intensity was obtained for the neat films of compound 9 and of compound 9 molecularly dispersed in the host 1,3-bis(N-carbazolyl)benzene (mCP; Figure 3c,d and Figure S3a in Supporting Information File 1). Low-energy absorption bands of molecular mixtures of compounds 6–9 and

• (ΔEST) between the lowest singlet and triplet states (Figure 4d and Figure S7 in Supporting Information File 1). A ΔEST value of 0.24 eV was obtained for compound 9. The highest photoluminescence quantum yield (PLQY) of 17.1% was obtained for the dilute toluene solution of compound 8 (Table 1). The neat

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• additional decarbamoylative step (Scheme 2). The decarbamoylation of compounds 3a–d was carried out by heating at 60 °C in neat H3PO4 for 90 minutes [62] and gave the corresponding β-enaminoketones 6a–d in good yields (Table 2). The NMR spectra of compounds 6 in DMSO-d6 in all cases indicated a mixture of Z

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• substrates. a) Substrate 7, reagents and conditions: 1) neat (5 equiv 5), 24 h; 2) Boc2O, NaHCO3, EtOH, ultrasound, 1 h, 88% (2 steps); 3) AcOH, hν (360 nm), 6 h, 74%. b) Substrate 9, reagents and conditions: 1) 11 (2 equiv), EtOAc, 23 °C, 1 h; 2) Boc2O, NaHCO3, EtOH, ultrasound, 23 °C, 1 h, 68% (2 steps); 3

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• , white neat solid, tR = 85 min). The LC–MS analysis of other fractions suggested the presence of very low amounts of compounds and these fractions were not further investigated. Series C (1.2 g) eluted with CH2Cl2/MeOH 97.5:2.5 (v/v) was divided into three portions of 400 mg each. Every portion was

• oil, tR = 8 min), 9 (1.3 mg, yellow oil, tR = 14 min), 3 (2.76 mg, white neat solid, tR = 16 min), and 1 (0.79 mg, yellow oil, tR = 22 min), respectively. Series E (294 mg) was further purified to yield compounds 5 (0.95 mg, white amorphous powder, tR = 35.20 min), 17 (6.1 mg, white amorphous powder

• , tR = 11.21 min), and 7 (1.45 mg, yellow neat solid, tR = 15.00 min), 4 (2.45 mg, white amorphous powder, tR = 22.00 min), respectively. Successive purifications of series F (898 mg) over normal (CH2CH2/MeOH 92:8, Nucleosil 120 OH Diol column) and reversed-phase preparative HLPC (Gilson, PLC 2020

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• was found that enones 2 were transformed into the corresponding 3-trichloromethylindan-1-ones 3 upon heating in neat TfOH at 80 °C for 2–10 h (Scheme 5). Under the same reaction conditions, hydroxy ketones 1 were cyclized into indanones 3 as well (Scheme 6). The structure of compound 3a was confirmed

• Brønsted and Lewis acids were also tested for this cyclization. Thus, enones 2a and 2e were not transformed into the corresponding indanones 3 in neat sulfuric acid (H2SO4) at room temperature for 3 days. That is in accord with literature data [19], where H2SO4 was used for dehydration of hydroxy ketones 1

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• of the catalyst for up to nine consecutive runs without loss of catalytic activity. Recently, Rohit et al. [86] described a modified Clauson–Kaas synthesis of N-substituted pyrrole with up to 89% yields by microwave irradiation at 120 °C in neat conditions by reacting amines 66 with 2,5-DMTHF (2) in

• derivatives 77 in good to excellent yields using a microwave-assisted and bismuth nitrate Bi(NO3)3∙5H2O-catalyzed reaction between various amines 76 and 2,5-dimethoxytetrahydrofuran (2) in neat, H2O or THF (Scheme 37). This approach provides different pyrrole derivatives without the use of sensitive or

• , H2O, neat), reaction times (10–22 minutes), and amount of oxone were investigated in order to stabilize the best reaction conditions. Among these, CH3CN as the best solvent system, 0.09 g of oxone, and a temperature of 110 ± 10 °C were chosen as optimized reaction conditions and used for the synthesis

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• 6.5) of probe G@TMeQ[6] (3.0 × 10−5 mol·L−1) to Hg2+ ions; (b) detection limit of probe G@TMeQ[6] to Hg2+ ions. (A) Titration 1H NMR spectra (400 MHz) obtained for TMeQ[6] with (a) 0.00, (b) 0.50, (c) 1.00 and (d) 1.20 equiv of G and (e) neat TMeQ[6] (5.0 × 10−4 mol·L−1); (B) titration 1H NMR spectra

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• . Elemental analyses were performed on a Flash 2000 Organic Elemental Analyser (Thermofisher). For samples containing chlorine, mercurimetric titration was used. IR spectra were recorded on a Nicolet iS50 equipped with an ATR diamond crystal (neat solid samples). Flash chromatography was performed using a

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• silica gel CC eluting with 100% CH2Cl2 afforded compound 2 (6.9 mg). 14β-Hydroxycassa-11(12),13(15)-dien-12,16-olide (1): amorphous, white powder; −22 (c 0.01, MeOH); UV (MeOH) λmax (log ε) 283 (4.20) nm; ECD (0.001, MeOH) λmax (Δε) 241 (+11.5), 271 (−10.4), 297 (+2.5) nm; IR (neat) νmax 3429, 2926

• ) 243 (+21.1), 330 (−4.70) nm; IR (neat) νmax: 2973, 1724, 1660, 1508, 1733 cm−1; 1H NMR (500 MHz, CDCl3) and 13C NMR (125 MHz, CDCl3) spectra, see Table 1; HRESI–TOF–MS m/z: 733.4305 [M + H]+ (calcd for C44H61O9, 733.4310). α-Glucosidase inhibitory assay α-Glucosidase inhibitory activity was performed

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• thioamidation reaction. After that, DMSO and NMP were also screened as solvents in the absence of base, but a longer reaction time was required for similar transformation (7 h) (entries 20 and 21, Table 1). A reaction of model substrates under neat conditions delivered product 1C in poor yield (entry 22, Table

• yield was observed (entries 2–5, Table 2). The oxidant TBHP (10 equiv) failed to deliver the anticipated product in good yield (36%, entry 6, Table 2). Similar results were obtained with H2O2 (25.0 equiv) under neat reaction conditions (entry 7, Table 2). Next, we performed the oxidative amidation

• , 0.25 mm). Column chromatography was performed using Spectrochem silica gel (60–120 mesh). Melting points were determined in open capillary tubes on the Precision Digital melting point apparatus (LABCO make) containing silicone oil, and the results are uncorrected. IR spectra (neat) were recorded on an

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

•  11), is only known as a synthetic compound. This hydrocarbon has first been obtained by dehydration of (+)-valerianol (42) with SOCl2 or POCl3, yielding – besides the Hofmann product as main product (75%) – (+)-39 (25%, [α]D20 = +167.5, neat) (Scheme 12B) [95]. After the first description of 39, also

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• system consists of a membrane reactor for the enzyme-mediated synthesis, a saturator vessel for the continuous supply of the amine donor, and a crystallizer where the desired product precipitates. Flow reactions can be performed as neat reactions in certain circumstances allowing for the precipitation of

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

• TADF emitter, imCzDPS (λPL = 440 nm, ΦPL = 44%, neat film) [19]. The EL of the LEEC was red-shifted at λEL of 470 nm compared to the PL. Following these initial reports Edman and co-workers demonstrated how neutral TADF small molecules [20], polymers [21], and dendrimers [22] could be employed in LEECs

• tert-butylcarbazole as donor groups [24]. Pym-CZ showed red emission in dichloromethane (λPL = 691 nm, ΦPL = 43%) and in the neat film (λPL = 583 nm, ΦPL = 15%). The emission is further red-shifted and attenuated in Pym-tBuCZ in dichloromethane (λPL = 740 nm, ΦPL = 8%) and in the neat film (λPL = 593

• DiKTa (λPL = 466 nm, FWHM = 40 nm, ΦPL = 70%, ΔEST = 0.20 eV, τD = 168 μs, 2 wt % mCP) in the same host [28]. Both emitters exhibited high ΦPL values in the mCP film at 71% and 61% under nitrogen, and these reduced to 57% and 53% in air for DiKTa-OBuIm and DiKTa-DPA-OBuIm, respectively. As neat thin

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• the covalent capsule 5 (made from resorcinarene caps connected by four dihydrazone units of ʟ-cysteine) with C60 and C70 fullerenes upon neat ball milling in a planetary ball mill (Figure 6). The mechanochemical complexation is remarkable since the porous capsule does not possess large enough openings

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• -pTC and BPy-p3C exhibit lone-pair electrons at the pyridinyl nitrogen atom and show prominent emission in the solid and aggregated states. We therefore demonstrated the switching of fluorescence using acid and base vapors in neat film (Figure 6a and Figure 6c). Both emitters exhibited switching of the

• fluorescence responses upon exposure to acidic and basic fumes on neat film (Figure 6a and Figure 6c). The intense green emission of the BPy-pTC film turned dark upon exposure to trifluoroacetic acid (TFA) vapor for 4 s (Figure 6a). The green fluorescence reappeared after neutralization with triethylamine (TEA

• -p3C aggregates in 90 vol % water/THF mixture. Fluorescence switching by acid and base fumes exposure: Emission spectra (λex = 375 nm) of (a) BPy-pTC and (c) BPy-p3C in neat film upon exposure to TFA and TEA vapor at room temperature. Fluorescence switching by addition of TFA and KOH to (b) BPy-pTC and

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• reaction conditions was carried out using p-cresol (1a) as the model substrate with 1.1 equiv of N-bromosuccinimide (NBS) for attempted monobromination. They were ground together at the speed of 100 rpm in an electrical grinder (EG) of Agate-made under neat conditions for 30 min. The reaction was

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• functionalization of the β-carboline framework. Accordingly, 3-formyl-9H-β-carbolines 6a–e were subjected to MBH reaction with acrylonitrile A and various acrylates B–E under neat conditions in the presence of DABCO as depicted in Scheme 2. All the products were furnished smoothly in 27–72% yield. During this study

• . For this purpose, the N-ethyl derivative 9e of 6e was prepared and subjected to MBH reaction with acrylonitrile A and methylacrylate B under neat conditions to generate the corresponding MBH adducts (10eA and 10eB) (Scheme 3). Interestingly, 9e showed more affinity towards this C–C bond forming

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• serve as reactants and solvents (neat liquid conditions). In addition, a long reaction time (12 h) is required to complete the reaction [15]. A general and efficient solvent-free borylation protocol that can be applied to liquid as well as solid aryl halides remains undeveloped. Recently

• 3). Reactions with DPEphos and XPhos, which are the optimal ligands for neat liquid conditions reported by Nechaev [15], also yielded only poor results (Table 1, entries 4 and 5). Other monophosphine ligands, such as SPhos, PCy3, and PAd3, did not improve the yield of 3a (Table 1, entries 6–8). The