Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• mesoporous system, resulting in a high surface area and uniform pore size. As a result, a high degree of dispersion of the piperazine active sites was achieved, leading to a catalyst exhibiting comparable activity and selectivity to that of a homogenous organocatalyst. Moreover, the hydrophobic surface of

Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles

• Javier Gómez-Ayuso,
• Pablo Pertejo,
• Tomás Hermosilla,
• Israel Carreira-Barral,
• Roberto Quesada and
• María García-Valverde

Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154

• functional group in the resulting Ugi adduct can be exploited in different post-condensation strategies to generate multiple fused nitrogen heterocycles in an easy manner. Fused heterocycles containing the piperazine and diazepine core. X-ray diffraction structures of pyrrolopiperazinones 9a (left) and 10a

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• reactive under the photocatalytic conditions, providing the corresponding 1,2-adducts 6a, 6b, and 6c smoothly in 73%, 93% and 34% yields, respectively. Commercially available amines with a broad range of heterocyclic rings (e.g., morpholine, piperazine, pyrrolidine, homopiperazine) also readily

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

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• mixed with 15 mL of the HDTMA solution under stirring. To this mixture, 50 mL of water, 1.5 mL of an iron chloride solution (1 mM FeCl × 6 H2O in 10 mM HCl), 4.3 g of anhydrous piperazine and 6.25 mL of 12 M hydrochloric acid were added. The resulting mixture was then diluted with water to a final

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

• ) by alkylation of 1a was patented in 1997 [79]. The process involves the alkylation of iminostilbene (1a) as a critical intermediate step (Scheme 33C). The alkyl halide linker of 148 was further functionalised by reaction with piperazine derivative 149 to give opipramol (5). 6.2 C-Functionalisation

Cholyl 1,3,4-oxadiazole hybrid compounds: design, synthesis and antimicrobial assessment

• Anas J. Rasras,
• Mohamed El-Naggar,
• Nesreen A. Safwat and
• Raed A. Al-Qawasmeh

Beilstein J. Org. Chem. 2022, 18, 631–638, doi:10.3762/bjoc.18.63

• MCF7) [13]. In 2008, Muhi-eldeen et al, synthesized a hybrid compound with 1,3,4-oxadiazole moiety and pyrrolidine connected with propargylic moiety showed antibacterial activity against Staphylococcus aureus and E. coli [14]. On the other hand, the coupling of piperazine with heterocyclic compounds

• products derived from piperazine derivatives with aromatic electron-donating (4d), electron-withdrawing (4b, 4c, and 4f), and aliphatic groups (4g, 4i, and 4j) were obtained. Moreover, the reaction with secondary aliphatic amines with various alkyl chains afforded products 4r–u, whereas products 4o and 4p

• piperazines with fluorinated aromatic (4b and 4c), a pyridinyl moiety (4e), and an alkylated piperazine (4i and 4j) were more active against S. aureus as well as derivatives with dialkylamino substituents with alkyl groups containing <5 carbon atoms (4q, 4r, 4s, and 4t) and pyrrolidine (4p). According to the

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• -catalyzed norbornene-mediated C–H activation [35] failed and gave 1,4-bis(2-bromophenyl)piperazine-2,5-dione (22, Scheme 5) as the sole product in 61% yield, which to our knowledge is not documented in the literature yet. Synthetic pathway (c) started from methyl 4-(2-nitrophenyl)-3-oxobutanoate prepared in

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

• Zhen-Sheng Jia,
• Qiang Yue,
• Ya Li,
• Xue-Tao Xu,
• Kun Zhang and
• Bing-Feng Shi

Beilstein J. Org. Chem. 2021, 17, 2488–2495, doi:10.3762/bjoc.17.165

• ][58]. We then explored the scope of multifarious amines. As displayed in Scheme 3, a range of cyclic amines, such as morpholine 4a,b, piperazine 4c, piperidine 4d–j and thiomorpholine 4l,m, reacted smoothly to give the amination products in 23% to 85% yields. A variety of synthetically useful

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

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• )-1-piperazine-ethanesulfonic acid) buffer (dimethylformamide/H2O 1:9) at 45 °C [118]. Initially, a 12-mer sequence containing the nucleobases guanine, thymine, and cytosine was tested by incorporating the earlier reported aminoethyl–PS linkage [118] (modification 82). However, cleavage products

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• . Moreover, TMS-substituted alkyne was suitable for this Huisgen reaction to achieve the desired triazole product. Next, some triazene scaffolds, such as dimethylamino-, pyrrolidine-, piperidine-, morpholine-, and piperazine-derived triazenes were screened. Aryl azides containing Br, I, Me, and MeO as well

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• synthesis has been recently reported by Loesche et al. [43]. The reaction between piperazine and different N-aryl-N’-cyanoguanidines in methanol at 120 °C afforded low to moderate yields for potential new cholinesterase inhibitors (Scheme 17A). Another example of microwave conditions has been provided by

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• )piperazine-N′-(2-ethanesulfonic acid), powder, 99.5%, Corning, NY) buffer solution (20 mM) in 150 mM NaCl was prepared and adjusted to pH 7.4 using 0.1 N NaOH. Chloroform (99.4%) was purchased from VWR (Avantor, Fontenay-sous-Bois). Ultrapure water was obtained from a Milli-Q (Millipore Corp.) system

Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system

• Yamato Fujihira,
• Yumeng Liang,
• Makoto Ono,
• Kazuki Hirano,
• Takumi Kagawa and
• Norio Shibata

Beilstein J. Org. Chem. 2021, 17, 431–438, doi:10.3762/bjoc.17.39

• common nitrogen-containing compounds such as pyridine, pyrazine, 1H-pyrazole, 1H-indole, 1-methyl-1H-indole, piperidine, and piperazine were subjected to screening. Pyridine and piperidine slightly hamper the reaction of 1g (Table 2, entries 2 and 7, 80–82%). Other nitrogen-containing compounds have more

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• shown in Figure 1) together with its IUPAC systematic name [15], SMILES [16] and InChI [17] keys. Chemists immediately recognize the aromatic and heterocyclic rings, the piperazine ring and the chloro-substituent in the 2D structure shown in Figure 3. Although the atomic coloring is not universal, most

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• for the construction of important intermediate 8 are discussed. One procedure involves the amidation of 1-Boc-piperazine with 3-acetyl-18β-glycyrrhetinic acid, prepared by the reaction of 18β-glycyrrhetinic acid with acetic anhydride without any solvent at 130 °C. The other procedure to prepare

• amides of 18β-glycyrrhetinic acid (c) are synthesized using various methods. A method involves the C30-position of the acyl chloride with symmetric piperazine [16][17]. In this case, the acyl chloride can be prepared without purification, and the total yield over two steps can reach 81% [16]. Such

• structures (c) can also be formed by treating the C30 carboxyl group with piperazine in the presence of activators (e.g., 1-ethyl-3-(dimethylaminopropyl)carbodiimide hydrochloride (EDCl), 1-hydroxybenzotriazole (HOBt) and trimethylamine [18]), the yield of piperazinyl amide derivatives was 80.6% [19]. These

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• reacted with 4-aminomethylpiperidine (AMP, 21) or piperazine (PIP) to afford G1-AAA–SBA-15 (G1-AMP–SBA-15, 22, or G2-PIP–SBA-15, 23) materials (Scheme 3). The resulting solid product was then filtrated and washed with methanol, dichloromethane, and tetrahydrofuran. The organic part of the G1-AAA–SBA-15

• containing piperazine), respectively. In the next step, Gx-AAA–SBA-15 was dispersed in an aqueous solution of HAuCl4 and stirred for a short time. The reduction of Au was accomplished using an aqueous solution of NaBH4. The obtained material was then centrifuged and washed with deionized water. The resulting

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• )-(E)-bis(1λ4-piperazine-1-carboxylate) (10): (E)-1,2-Bis(4-chloro-2-methoxyphenyl)diazene (8, 100 mg, 0.32 mmol) was dissolved in toluene in a pressure tube. Then, 1-Boc-piperazine (180 mg, 0.96 mmol), tris(dibenzylideneacetone)dipalladium(0) (29.3 mg, 0.032 mmol), RuPhos (29.8 mg, 0.064 mmol), and

• (3-bromo-5-methoxy-4,1-phenylene)-(E)-bis(1λ4-piperazine-1-carboxylate) (11): Di-tert-butyl 4,4'-(diazene-1,2-diyl)bis(3-methoxy-4,1-phenylene)-(E)-bis(1λ4-piperazine-1-carboxylate) (10, 30 mg, 0.04 mmol) was dissolved in DCM, palladium acetate (1 mg, 0.004 mmol) was added, and the resulting mixture

• ]+ calcd for C32H45Br2N6O6, 767.1767; found, 767.1762. (E)-1,2-Bis(2-bromo-6-methoxy-4-(piperazin-1-yl)phenyl)diazene (5): Di-tert-butyl 4,4'-(diazene-1,2-diyl)bis(3-bromo-5-methoxy-4,1-phenylene)-(E)-bis(1λ4-piperazine-1-carboxylate) (11, 15 mg, 0.02 mmol) was dissolved in 5 mL of DCM, and 0.25 mL of TFA

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• ]. We initially introduced the piperazine unit in a quantitative yield with unprotected piperazine (not shown) [37][38]. However, purification and isolation were problematic and we found it more convenient to use Boc-piperazine (70% yield) to obtain 11. Hydrolysis of the ethyl ester (96%) with LiOH and

• mechanism. a: Rh2(esp)2 (1 mol %), CH2Cl2, rt, Cs2CO3, 50–52%. b: EtOH, reflux, 24 h, 65%. Synthesis of norfloxacin. a: Cl-EDA (1.3 equiv), Rh2(esp)2 (1 mol %), toluene, rt, Cs2CO3, 75%. b: EtOH, reflux, 24 h, 90%. c: EtI, K2CO3, DMF, 90 °C, 24 h, 85%. d: Boc-piperazine, K2CO3, CH3CN, reflux, 3 d, 70%. e

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• aggregation of isotropic nanoparticles, the 1,4-bis(2-(2-(2-(2-aminoethoxy)ethoxy)ethoxy)ethyl)piperazine-based AAP linker molecule (dAAP) has been successfully applied before and it was synthesized as described in detail in the literature [38]. This divalent linker molecule can form a light-responsive 1:2

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• Co., Ltd (Shanghai, China), GC5A [26], P-TPE [73] and TPS [74] were prepared according to the previous literature procedures. Samples The HEPES buffer solution of pH 7.4 was prepared by dissolving 2.38 g of 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES) in approximate 900 mL double

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives

• Peng Li,
• Yongqi Wu,
• Tingting Zhang,
• Chen Ma,
• Ziyun Lin,
• Gang Li and
• Haihong Huang

Beilstein J. Org. Chem. 2019, 15, 703–709, doi:10.3762/bjoc.15.65

• strong nucleophilicity of piperazine and morpholine, the substrates with electron-donating/withdrawing and halogen groups smoothly delivered the N-substituted 2-aminobenzothiopyranones 4j–o and 4t,u in good to excellent yields. Specifically, the substrates containing a strong electron-withdrawing group

Regioselective addition of Grignard reagents to N-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ⁵-2-oxopiperazines

• Valentine R. St. Hilaire,
• William E. Hopkins,
• Yenteeo S. Miller,
• Srinivasa R. Dandepally and
• Alfred L. Williams

Beilstein J. Org. Chem. 2019, 15, 72–78, doi:10.3762/bjoc.15.8

• ; Introduction Pyrazine and piperazine ring systems are key structural elements in a large number of biologically active molecules [1][2][3][4][5][6]. Compounds containing these scaffolds were shown to behave as anticancer agents [2][3][4][5], sodium channel blockers [5], and also display antiviral activity [7