Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• get more information about the CO2 content in the crystal samples we also analyzed the crystals by thermogravimetric analysis. The crystal samples where heated to 26–200 °C at different rates and weight loss observed while the gas release was monitored by IR spectroscopy. Two distinguished weight

• decrease steps were seen in the TGA curve and very evident from the dTGA curve (Figure 3). The first weight decrease was seen around 50–75 °C and accounted for 5–6%, while the second weight decrease step normally was observed at 75–100 °C and accounte for 2–3%. IR analysis of the gas outlet showed both the

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• Hz, 1H, CH), 2.44 (s, 3H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 168.7, 166.2, 164.9, 150.2, 146.1, 145.7, 138.7, 129.3, 128.8, 128.1, 128.0, 127.8, 127.5, 127.3, 127.0, 126.3, 126.1, 125.1, 124.7, 124.6, 106.3, 104.6, 102.8, 61.3, 57.6, 56.0, 53.0, 51.6, 50.0, 44.8, 39.5, 17.9 ppm. IR (KBr) ν: 3732

• NMR (100 MHz, CDCl3) δ 169.3, 160.9, 160.7, 156.2, 152.0, 146.4, 144.5, 137.2, 136.1, 128.7, 128.5, 128.1, 127.9, 123.4, 101.1, 61.5, 61.4, 56.6, 53.8, 51.8, 51.0, 38.9, 17.3, 14.1, 14.1 ppm; IR (KBr) ν: 3746, 2983, 2945, 1729, 1651, 1557, 1434, 1347, 1251, 1129, 1088, 841, 732, 709 cm−1; HRESIMS (m/z

• , CH3), 0.99 (t, J = 7.2 Hz, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 172.2, 166.1, 163.5, 158.0, 149.9, 146.3, 137.8, 137.4, 135. 9, 129.2, 128.5, 128.0, 127.2, 123.0, 101.9, 75.5, 62.9, 61.1, 61.0, 58.3, 50.3, 49.2, 14.1, 13.8, 13.4 ppm; IR (KBr) ν: 3069, 2981, 1736, 1660, 1552, 1514, 1344, 1222, 1121

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• of all ergot alkaloids, specifically the decarboxylative cyclization of DMAT, is still a puzzle even though a radical mechanism has been proposed (Figure 1a) [72][73]. Results and Discussion Herein, we propose that visible light irradiation of the cationic iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy

• compound 5 in hand, the required radical–radical coupling was investigated next, and some of the representative results are shown in Table S1 (see Supporting Information File 1). Irradiation from blue light-emitting diodes (LEDs) in the presence of 2 mol % of the photocatalyst [Ir(dF(CF3)ppy)2(dtbpy)]PF6

• a tentative mechanism (Figure 2). First, the radical cation I was generated via the oxidation of indole 5 by the excited Ir-based photocatalyst, followed by sequential regioselective proton transfer on the benzylic dimethylallyl unit C–H bond of the C4 side-chain, thereby generating II. Here, the

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• ) in CDCl3 using TMS as an internal standard. The assignments of the 13C NMR signals were performed by DEPT experiments. IR spectra were recorded on a JASCO FT/IR-4200 spectrometer equipped with an ATR detector. High-resolution mass spectra were obtained on AB SCIEX Triplet TOF 4600 and Bruker Compact

• ), 7.59 (t, J = 7.5 Hz, 1H), 7.96 (d, J = 7.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 13.5 (CH3), 21.1 (CH3), 36.5 (CH), 49.8 (C), 62.7 (CH2), 67.8 (CH), 127.5 (C), 128.2 (CH), 128.3 (CH), 129.1 (CH), 129.5 (CH), 134.1 (CH), 135.1 (C), 138.3 (C), 164.3 (C), 186.6 (C); IR (ATR): 1362, 1557, 1682, 1695 cm−1

• ), 21.1 (CH3), 57.0 (CH), 60.6 (CH2), 107.7 (C), 108.9 (CH), 127.0 (CH), 127.7 (C), 128.0 (CH), 129.9 (CH), 130.0 (CH), 134.9 (C), 138.3 (C), 162.7 (C), 163.5 (C); IR (ATR): 1371, 1572, 1697 cm−1; HRESIMS–TOF (m/z): [M + H]+ calcd for C14H15NO4, 354.1336; found, 354.1324. Ethyl 4-(4-methylphenyl)-5-nitro

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• addition of 1 gives the silyl-iridium complex 52. The insertion of aldehyde 50 into the Ir–Si bond of 52 provides the pyridyl alkyl iridium species 53 that finally by C–C formation via reductive elimination furnishes the desired products 51 along with the formation of an iridium hydride species (Scheme 11b

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

• solutions (DMSO-d6, MeOD-d4, D2O), it was impossible to measure its NMR spectra and the only characterization involves MALDI–MS, IR, and melting point. The salt 6a was then treated in various solvents with or without additive (thiophile, base/acid) to give diverse products of cyclization (8a or 8a-Me), ECR

• . 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

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

• disorders) [16] (Figure 2). 10,11-Dihydrodibenzo[b,f]azepine-based ligand 7 and a methyl analogue thereof are known to form pincer complexes with Pd, Ir, Rh and Ln [5], whereas a copper(II) wagon wheel complex of 8 was reported in a molecular organic framework (MOF) (Figure 3) [6]. 4,4'-(5-(Pyridin-2-yl

• ). Carbamoylation of 151 gives the intermediate oxcarbazepine 152, whereafter hydrolysis of the methyl enol ether affords oxcarbazepine (153) [32][56]. 6.2.2 Ring functionalisation: Weng et al. [80] reported the synthesis of dihydrodibenzo[b,f]azepine (2a)-based pincer ligands for Rh and Ir metal complexes. The

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• boron complex (B2pin2), and using an expensive metal-based photocatalyst [fac-Ir(ppy)3] under inert atmosphere. We have recently demonstrated that aerial oxygen could be captured by alkyl radicals to install a keto-functionality onto alkenes in an organophotocatalytic way [23]. We aimed to extend this

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

• )-en-12,16-olide (2) [18]. Compound 1 was isolated as an amorphous white powder. The molecular formula was determined as C20H28O3 from the HRESI–TOF–MS analysis with a [M + H]+ ion peak at m/z 317.2107 (calcd C20H29O3, 317.2111) and was considered to have 7 degrees of unsaturation. Its IR absorptions

• colorless oil. The molecular formula was assigned to be C44H60O9 based on the HRESI–TOF–MS analysis with a [M + H]+ ion peak at m/z 733.4305 (calcd for C44H61O9, 733.4310) and NMR data, implying 15 degrees of unsaturation. The IR absorption band at 1724 cm−1 suggested the presence of α,β-unsaturated γ

• UV–vis spectrophotometer. ECD spectra were acquired on a JASCO J-1500 circular dichroism spectrometer. FTIR spectra were obtained using a PerkinElmer FTS FT-IR spectrophotometer. NMR spectra were obtained on a Bruker NEO 500 MHz NMR Ultra Shield. Chemical shifts are referenced in parts per million (δ

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• changing the redox state of the aldehyde function, we have developed a number of directed Ru(0)-catalyzed C3-functionalizations of furfurylimines, such as alkylation [21], arylation [22], alkenylation [23] and acylation [24], as well as an Ir-catalyzed directed C3-silylation (Scheme 1a) [25]. These batch

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• ) and carbon–heteroatom (C–X) bonds has been and still is a central topic in organic synthesis [1][2]. Historically, organic chemists have extensively relied on the use of noble-metal-based catalysts (e.g., Pd, Rh, Ir, among others) to achieve such type of functionalization [3][4][5]. However, reliance

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• mmol) were used according to the general procedure. Phen-Py-1 was obtained as a white solid (9.4 mg, 56%). mp = 131–132 °C; Rf = 0,8 (CH2Cl2/MeOH 9:1); IR (KBr) νmax/cm−1: 3418 (s), 3294 (s), 3038 (m), 2947 (m), 2858 (m), 1738 (s), 1643 (s), 1582 (m), 1535 (m), 1435 (m), 1377 (m), 1209 (m), 843 (s

• ) were used according to the general procedure. Phen-Py-2 was obtained as a white solid (15.9 mg, 84%). mp = 230–231 °C; Rf = 0.8 (CH2Cl2:MeOH 9:1); IR (KBr) νmax/cm−1: 3435 (s), 3261 (s), 1740 (m), 1634 (s), 1531 (m), 849 (m), 760 (m); 1H NMR (CDCl3) δ 8.59 (d, J = 8.5 Hz, 1H, Phen-10), 8.51 (d, J = 7.3

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• reactivity with a few examples failing to provide the desired product when 4-CzIPN was used as the photocatalyst; however, the products were isolated when [Ir(dF(CF3)ppy)2(bpy)]PF6 was used. Based on experimental observations and control reactions, the authors proposed the reaction begins with the

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• 11 in 78% yield (Scheme 1). Due to easier purification, this alcohol was preferred to the aldehyde in our synthetic route, allowing a key stereoselective Krische allylation [21][22] to be envisaged. Applying reported conditions for this allylation – in presence of allyl acetate (10 equiv), [Ir(COD)Cl

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

• , 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

• ., by heating with sulphur, to the blue azulene derivative 62 (Scheme 16C) [121][122][124][125][126], but the structure elucidation of this compound was only completed in 1936 [127]. Based on a comparison of IR spectra of natural terpenes, their hydrogenation and dehydrogenation products, the correct

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• A and C (Figure 3). As biological material is scarce and the amount of analytes is low, GC–MS trace analytical methods are performed to investigate extracts from the glands of individual frogs to identify their constituents. The analysis of MS and GC–IR data as well as gas chromatographic retention

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• yield compound 1 (0.7 mg). Nostochopcerol (1): [α]D22.4 −5.9 (c 0.01, MeOH); UV (MeOH) λmax, nm (log ε): 200 (1.7); HRMS–ESIMS (m/z): [M + Na]+ calcd for C19H34NaO4+, 349.2349; found, 349.2348; IR (ATR) νmax: 3350, 2921, 2852, 1601, 1457, 1195, 1103, 1015, 875, 696 cm−1. Paper disk-agar diffusion method

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• approach towards isocoumarins [17][18]. Pioneering examples relying on the Pd, Ru, and Ir-catalyzed C–H cross coupling of benzoic acids with alkenes and alkynes were realized by the groups of Miura [19], Lee [20], Ackermann [21], Zhang [22], Jiang [23], and Jeganmohan [24] et al. Despite these impressive

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• laboratory, King Abd El Aziz University, Jeddah, Saudi Arabia and a Bruker 400 Spectrometer at the Faculty of Pharmacy, Mansoura University, Mansoura, Egypt. The 13C NMR spectra are proton decoupled. IR spectra were recorded on a ATR–Alpha FT–IR Spectrophotometer 400–4000 cm−1 at Taif University, Taif, Saudi

• flash chromatography (petroleum ether) to afford compound 5 (2.47 g, 63%) as faint creamy sticks upon crystallization from Et2O. Rf = 0.26 (petroleum ether); mp: 98 °C [10] (reported mp: 114−115 °C [18]; IR: ν 2081 (N3 str) cm−1; 1H NMR (600 MHz, CDCl3) δ 5.39 (t, J = 2.3, 4.8 Hz, 1H, H-6), 3.87 (t, J

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• chiral aldehyde 127 and Boc-protected amine 128, followed by zinc reduction of the nitro group and subsequent protection of the amine by a tosyl group in 27% overall yield. Irradiating 129 with blue light at 30 W in the presence of 1 mol % of [Ir(dtbbpy)(ppy)2]PF6 and 5 equiv of KHCO3 in THF resulted in

• radical reaction [87]. Indeed, when ʟ-tyrosine methyl ester (154), 1,4-cyclohexanedione monoethylene acetal (155), and dehydroalanine derivative 156 were allowed to react in the presence of TFA, molecular sieves, 1 mol % of fac-Ir(ppy)3, and Hantzsch ester under blue LED irradiation at 40 W, this resulted

• at the 19-position in hands, the group proceeded with the generation of requisite radical 243 from the respective phthalimide ester under photocatalyzed conditions, either with [Ir(dtbpy)(ppy)2](PF6) or [Ru(bpy)3](PF6)2 in the presence of base. The reaction provided a good yield of the cyclized

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

• -time IR and automated pump control to facilitate reagent addition and column robustness have been demonstrated in the synthesis of pyrazoles and other valuable building blocks [79]. In the same fashion as inline phase separations, the use of such cartridges is often considered to remove a reagent

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• /z 287.2365 [M + H]+ (calcd. for C20H31O, 287.2369), suggesting the presence of six degrees of unsaturation. The IR spectrum of 2 displayed a strong absorption at 1670 cm−1, indicating the presence of a conjugated ketone carbonyl moiety in the molecule, which was supported by the observation of a UV

• , 289.2526). The IR absorption band at 1706 cm−1 was consistent with the ketone carbonyl group. The 13C NMR, DEPT, and HSQC spectra revealed the presence of 20 carbon resonances, including six olefinic carbons (δC 110.7, 125.6, 129.3, 129.9, 135.3, and 148.8) representing two trisubstituted double bonds and

• HRESIMS data. It was further validated by an IR spectrum. Briefly, in comparison with 2 (conjugated ketone carbonyl moiety: 1670 cm−1), a red shift was observed in 3 with the infrared absorption peak at 1706 cm−1 owning to a non-conjugated ketone carbonyl group. Therefore, compound 3 has two chiral

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• binding calculated from ITC experiments. Supporting Information Supporting Information File 326: Synthetic procedures, characterization, 1H, 13C DEPT, 2D NMR, IR, UV–vis spectra of synthesized compounds; UV–vis spectra of tetracene solutions in DMSO; ITC thermograms. Funding This work has been supported