Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• DMF. The reaction was performed at 130 °C, as we believed that high temperature will promote the cyclization of the sterically hindered intermediate 3a, but no DBDAP was achieved under these conditions (entry 1, Table 3). Next, Pd(OAc)2 was employed under ligand-free conditions, but again the desired

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

• , acrylates, allenes, and alkynes as coupling partners achieving the functionalized C(sp2)–H-olefinated pyridine frameworks via metal catalysis. ortho-C–H Alkenylation In 2012, Huang and co-workers [74] disclosed a ligand-free oxidative cross-coupling reaction of pyridine with acrylates, acrylamides, and

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• cross coupling reaction developed by Kochi, leading to better yields, with no need to use an excess of one of the coupling partners (Scheme 2b) [12]. The yields obtained using this ligand-free method are comparable to those obtained in recent palladium-mediated alkyl–vinyl cross-couplings using

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• were taken as partners in a Buchwald coupling (Scheme 22a) [44]. On the other hand, in 2015, Organ’s group performed a phosphine-ligand free Buchwald amination of 5-chloroindole (164) with amine 165 to give the desired product 167, where the use of the Pd-PEPPSI-IPentCl precatalyst 166 in presence of

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• high importance in the field of Alzheimer’s disease studies [169]. In 2020, Xu and co-workers described an unprecedented dual C–H functionalization of indolin-2-ones and benzofuran-2-ones via an oxidative C(sp3)–H cross-coupling protocol catalyzed by inexpensive FeCl3 and ligand-free conditions (Scheme

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

• Valeria Nori,
• Antonio Arcadi,
• Armando Carlone,
• Fabio Marinelli and
• Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

• catalytic system showed that the ligand-free PdCl2 was the most effective catalyst (Table 1, entry 14). Other catalysts such as Pd(PPh3)4, Pd/C or Pd(OAc)2 provided inferior results (Table 1, entries 11–13). We then examined the reaction of 2a with 1.5 equiv of a variety of arylboronic acids. Using the

• presence of a catalytic amount of the ligand-free PdCl2 in environmentally friendly ethanol, achieve an efficient regio- and stereoselective synthesis of 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones 4. It is worth noting that, during the preparation of this paper, a related article focused on the

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• . Interestingly, this protocol was applied to the total synthesis of (R)-oxiracetam (142), a drug used for the treatment of Alzheimer’s disease [61]. In a similar way, a ligand-free, intramolecular silylarylation of unsaturated amides 143 could be performed, albeit following a radical pathway leading to cyclic

• carbenoid insertions using spiro-bisimine ligand L25 at cryogenic temperatures (Scheme 39A). Ollevier, however, focused on making these reactions more general under ligand-free conditions at ambient temperature, and without the asymmetric component (Scheme 39B). The substrate scope was already broad

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• aromatic or aliphatic, only in case of triazoles substituted with an acetate group the final product was obtained in 66% yield. An open-flask, one-pot, Cu(II)-catalyzed ligand-free approach towards C–N bond formation was reported by Rasheed et al. [116]. The reaction was catalyzed by Cu(OAc)2 with cesium

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• microwave heating [7][8][9][10][11][12][13][14][15], ultrasonication [16][17][18], ligand-free methodologies [19][20][21][22][23][24][25] and the use of water-soluble palladium pre-catalysts/catalysts [26][27][28][29][30]. The latter is the preferred choice since it allows for the reusability of the

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• and lifetime. Apart from that, ligand-free Pd catalysts are also known in the literature [11][12]. However, homogeneous Pd catalysis often requires catalyst loadings in the order of mol % to achieve effective coupling and suffers from catalyst re-use and recycling problems [11][13]. Furthermore

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• was paid on trifluoroacetates. Trifluoroacetate is readily available and one of the cheapest and most convenient sources of the trifluoromethylation for both industrial and medicinal purposes. In 2011, a practical and ligand-free Cu-catalyzed decarboxylative trifluoromethylation of aryl iodides was

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

• Andrea Porcheddu,
• Evelina Colacino,
• Giancarlo Cravotto,
• Francesco Delogu and
• Lidia De Luca

Beilstein J. Org. Chem. 2017, 13, 2049–2055, doi:10.3762/bjoc.13.202

• the bpy/CuI/NMI catalyst system with Fe(NO3)3·9H2O, a cheaper, ligand-free co-oxidant (Scheme 1) [29][30]. This made the oxidative process more appealing for pharmaceutical applications, and specifically beneficial in the preparation of fragrances and food additives [31]. Despite the advances, the

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• media became more and more attractive [11]. Despite there are several strategies for palladium-catalyzed cross-coupling reactions in water, such as microwave heating [12], ultrasonic irradiation [13][14] and ligand-free methodology [15][16], the more efficient and preferable one is the use of water

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• an economic and environmental standpoint, it is highly desirable to develop more environmentally friendly synthetic methodologies. Several studies were dedicated to the design of a novel catalytic system, that are more accessible, robust, efficient and ligand-free [19]. In that sense, nanoparticles

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• , Zhejiang, China 10.3762/bjoc.13.160 Abstract In this paper, the synthesis of a cheap, reusable and ligand-free Pd catalyst supported on MgAl layered double hydroxides (Pd/MgAl-LDHs) by co-precipitation and reduction methods is described. The catalyst was used in Heck reactions under high-speed ball

G-Protein coupled receptors: answers from simulations

• Timothy Clark

Beilstein J. Org. Chem. 2017, 13, 1071–1078, doi:10.3762/bjoc.13.106

• below. Mechanism of G-protein signaling Figure 3 and Figure 4 show modeled structures to illustrate the mechanisms of signaling in GPCRs. In the simulations discussed below, the G-protein is represented only by the α-subunit, which binds directly to the GPCR. In the ligand-free state shown in Figure 3a

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• . Although the ligand highly increased the catalytic activity of the copper catalyst, it was often used in large amount, making the process expensive and difficult in removing it. In this context, some ligand-free protocols have been developed by enhancing the reaction activity in some other ways. In 2011

• noting that the developed protocol could be easily applied to the synthesis of anilines and aryl thiols. In 2014, the Jiang and Han group used a copper-doped graphitic carbon nitride catalyst Cu-g-C3N4, which was prepared from urea and CuNO3, and developed a ligand free protocol for the synthesis of

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• > NO2 > CO2H > OMe > F > H [38][39]. The results of a series of the preliminary reactions are summarized in Table 1 and in Supporting Information File 1. The ligand-free system based on palladium acetate (10 mol %) or palladium chloride (10 mol %) in the presence of K3PO4 and K2CO3 in a mixture of

• toluene/H2O (6:1) was initially tested. Recently, several ligand-free catalytic systems have been applied successfully in Suzuki cross-coupling reaction between various aryl and heteroaryl halides and triflates with alkenyl and arylboronic acids [40][41][42][43]. The evaluation of such catalysts

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• reactions, we hypothesize that the highly electron-donating PyC ligand facilitates the oxidation of gold(I) to gold(III). As triphenylphosphine is known to be easily oxidized to triphenylphosphine oxide under the current oxidative conditions, the ligand-free gold(III) species is thought to be an active

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• the reaction in the synthesis of indoles was later achieved by mean of ligand-free condition via the co-catalysis of Cu(eh)2 (copper(II) 2-ethylhexanoate) and TEMPO under oxygen atmosphere [68]. C(sp)–H bond amidation The C(sp)–H bond in terminal alkynes is more acidic than equivalent alkane and

Coupling of α,α-difluoro-substituted organozinc reagents with 1-bromoalkynes

• Artem A. Zemtsov,
• Alexander D. Volodin,
• Vitalij V. Levin,
• Marina I. Struchkova and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2015, 11, 2145–2149, doi:10.3762/bjoc.11.231

• dimethylformamide under ligand-free conditions. Keywords: 1-bromoalkynes; cross-coupling; organofluorine compounds; organozinc reagents; Introduction gem-Difluorinated organic compounds have attracted increasing attention nowadays due to their applicability in medicinal chemistry [1][2] and other fields. Indeed

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• reaction. Ghosh, Dhara et al. also reported a synthesis of substituted phenanthridines based on palladium-mediated Suzuki coupling (Scheme 14) [34][35]. Aerobic ligand-free domino Suzuki coupling–Michael addition reaction in the presence of Pd(OAc)2 and K3PO4 as a catalytic system in H2O was catalysed by

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• bulky THIQ residue. The group of Sames reported a ligand-free palladium-catalyzed protocol for C2-arylation of 3-substituted indoles [35]. However, this method did not give any conversion to C2-arylated products on our substrates. Yang et al. reported a mild palladium-catalyzed C2-arylation at room