Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• groups in symmetric and asymmetric ligands widely applied in various organic transformations [7]. Especially, bisoxazolines are a kind of widely applied chiral ligands in diverse transition metal-participating asymmetric catalysis [8][9][10]. Several methods have been developed for the efficient

• in the presence of electrophilic reagents [18][19] (Scheme 1d). Aziridines can be considered as the NCC structural fragment after ring-opening and have been applied in the synthesis of aziridine-imine-containing chiral tridentate ligands [20], 2-alkylideneoxazolidines [21], and N-vinylamides [22]. We

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• )benzimidazole or its N-alkylated derivatives as the ancillary ligands (N^N) [43]. The prepared Ru(II) derivatives were found efficient in the synthesis of α-amino nitriles from amines via a one-pot strategy. This synthetic pathway comprises two consecutive reactions including photooxidation of the amine and the

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• , C. tropicalis, and C. glabrata standard strains. A deep conformational survey was monitored using DFT calculations with the aim to explain the importance of the final conformation in the biological experimental results. Keywords: antituberculosis; bidentate ligands; DFT; nickel; palladium

• ligands that could coordinate several metal centers with the aid of sulfur, nitrogen or oxygen donor atoms that allow multiple bindings [13]. Moreover, compounds bearing a –C(O)NHC(S)– moiety and their metal complexes have assorted biological and pharmacological properties such as anti(myco)bacterial

• Discussion Synthesis of L1-M, L2-M, and L3-M According to our experience, concerning the most bioactive structural arrangement, the ligands L1, L2, and L3 were selected for this study (Scheme 1). Using the known methodology developed by our group, the starting compounds endo-prolinates 1, generated by 1,3

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• electron-withdrawing group that enhances the effects of many bioactive molecules due to a significant improvement in stability, lipophilicity, and resistance to enzymatic degradation [17][18]. Also, it has been widely applied as a special alkyl substituent for ligands of phosphorescent heavy metal

Me₃Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines

• Krishna M. S. Adusumalli,
• Lakshmi N. S. Konidena,
• Hima B. Gandham,
• Krishnaiah Kumari,
• Krishna R. Valluru,
• Satya K. R. Nidasanametla,
• Venkateswara R. Battula and
• Hari K. Namballa

Beilstein J. Org. Chem. 2021, 17, 2765–2772, doi:10.3762/bjoc.17.186

• ] receptors. They are useful in the synthesis of phosphorescent materials [22][23][24], fluorosensors [25]. and also found as chiral ligands in a variety of transition metal catalysts [26][27][28][29][30]. Given the pharmacological promiscuity of this scaffold, extensive efforts from different groups led to

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• active compounds in medicinal chemistry and as chiral ligands in asymmetric catalysis. Chiral phosphoric acids are recognized as efficient organocatalysts for a variety of enantioselective transformations. In this review, we summarize the recent development of chiral phosphoric acid-catalyzed synthesis

• construction of axial chirality [7][8][9][10][11][12][13][14]. Axially chiral biaryl and heterobiaryl units are widely used as basic building blocks for chiral ligands [14], chiral catalysts [14][15][16][17] (Figure 1), various natural products, drugs and bioactive molecules [18][19], pharmaceutical agents [20

• ][21] (Figure 2), and chiral building blocks in modern organic synthesis [5]. During the past decades, both C2 and non-C2 symmetric axially chiral biaryl compounds such as BINAP, BINAM, NOBIN and their derivatives BINOL have played a crucial role as ligands in the development of transition-metal

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• first step, vinyl triflate undergoes oxidative addition to give complex 4, which subsequently transmetalates with arylboronic acid to form palladium complex 5. In the case of Pd(PPh3)4, reductive elimination occurs to give enamide 2. However, using catalysts with very bulky ligands, such as Pd(dppf)Cl2

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• terminal alkynes has been achieved in a continuous-flow microreactor through 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)/copper relay catalysis. The reaction is easily scalable and requires low concentration of supporting electrolyte and no external chemical oxidants or ligands, providing straightforward

• electrocatalytic dehydrogenative cross-coupling reaction of tetrahydroisoquinolines with terminal alkynes in continuous flow (Scheme 1D). These reactions require low loadings of supporting electrolyte and proceed through Cu/TEMPO relay catalysis without need for additional ligands. Results and Discussion The

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• solubilizers, bile acids are now recognized as metabolism regulators through specific receptors: farnesoid X receptor (FXR) and Takeda G protein receptor 5 (TGR5) [1][2][3]. Research efforts to find ligands for these receptors initiated several synthetic studies where bile acids are being used as a starting

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• catalyst in the presence of a substrate possessing a prochiral migrating group or (2) stereospecifically by means of a chiral α-ketol. As an example of an enantioselective rearrangement, complexes of nickel(II) with a series of chiral 1,2-diaminopropane or pyridineoxazoline ligands were evaluated for their

• with greater than 80% ee. As a third example of an enantioselective α-ketol rearrangement, Dai et al. used a chiral Al(III) catalyst to induce the rearrangement of 3 (Ar = Ph) and several aryl derivatives 9 (Figure 4) [6]. Among the N,N′-dioxide ligands explored, 11, which was derived from ʟ

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

• alter cryogel pore size and mechanical properties. In addition, Tam et al. demonstrated the optical transparency with three-dimensional spatial control of immobilised bioactive growth factors using multiphoton patterning and cellular response to immobilised ligands as shown in Figure 6 [94]. Researchers

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• cooperative steric hindrance based on bulky substituents at the 2,9-position of the phenanthroline moiety [32][33]. Alternatively, heteroleptic CuI complexes with phenanthroline and bulky chelating phosphine ligands were also synthesized [30][34][35]. The photophysical properties are dramatically modified by

• requirements of a given photochemical process. The different ligands and CuI complexes are shown in Scheme 3 [21][30]. The catalysis mechanisms of these CuI complexes are discussed in the following sections. 2. Mechanisms underlying the photoredox catalysis of copper complexes The mechanisms underlying the

• photoredox catalysis of CuI complexes with different ligands were investigated by Reiser’s group [21]. Other studies have since provided more information on the photoredox mechanisms underlying the catalysis of copper complexes [37]. In general, redox-active copper complexes include CuI and CuII complexes

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• vinylindoline derivatives 125 was achieved by utilizing chiral ligands like chiral binaphane (Scheme 37) [91]. They had observed that the formation of six- and seven-membered rings required elevated temperatures. Subsequently, the same group studied the cyclization of arylene 126 to furnish naphthalene

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• , resulting in a multitude of applications in dyes [11], molecular electronics [12], and oxidants or ligands in organic chemistry [13][14]. This wide range of applications has long fueled an interest in exploring innovative ways of functionalizing quinones. However, arylation of (benzo)quinones has proven to

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• increase activity [11][12]. These nanoparticles have been decorated with targeting ligands to enhance the accumulation of the drug in cancer tissue. The activity of arsenic drugs could, however, also be enhanced by targeting mitochondria inside the cells, the target of action of arsenic drugs. To the

• efficiency. Micelles are ideal carriers when designing a nanoparticle with an abundance of functional groups on the surface, which could be conjugated with targeting ligands such as TPP. Moreover, they have already been used to successfully deliver arsenic drugs [28][29][30][31][32], highlighting their

• explore if the attachment of mitochondria targeting ligands can enhance the activity of PENAO using the nanoparticles that were recently described in our group [28][42]. Results and Discussion Synthesis of Micelles by PISA Initially two nanoparticles were prepared that had comparable particle sizes, which

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• (preQ1) [1]. Thus far, present-day riboswitches have only been known to bind – but not to be able to react – with their ligands [2][3]. This new finding now opens exciting avenues for the development of RNA labeling tools [4], in particular, for RNA methylation, and more generally, for RNA alkylation. To

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• catalysis (Scheme 17) [71]. The reaction relied on the chiral biimidazoline ligand 30, which gave the best results among various tested chiral bioxazolines and chiral biimidazoline ligands. Notably, the aryl substituent at the imidazoline nitrogen of the ligands significantly affected the product yields and

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• observed selectivities in metathesis reactions, H-bonding interactions between chloride ligands as H-bond acceptors and OH or NH functions in the metathesis intermediate appear to be determining [35][36]. Selectivity derived from chelation is considered to be an another important contributor. Through the

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

• have been used as additives in these reactions and are suggested to act as ligands, assist proton transfer and promote the formation of oligovanadates by decreasing the pH value of the solution. The mechanisms of some vanadium-mediated oxidation reactions of alkanes have been studied, most of them

• compounds to produce the corresponding biaryl products with high enantiopurity using vanadium chelated with chiral ligands, such as tridentate asymmetric imine ligands, have been reported. For instance, (S)-binol derivatives could be successfully prepared from 2-naphthols using a dimeric vanadium complex

• -rich ligands along with the addition of Brønsted and Lewis acids, such as acetic acid and LiCl, was suggested to account for the suitability of the method for the coupling of oxidatively resistant substrates. The usefulness of this method was demonstrated in the preparation of the bicarbazole moiety

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• . The efficiency of the solvent radical cage in maintaining the geminate radical pair could be modulated by stereoelectronic changes in the ligands of the transition-metal complexes to favor a desired pathway. One reaction particularity that was sensible to the solvent cage efficiency was the

One-step synthesis of imidazoles from Asmic (anisylsulfanylmethyl isocyanide)

• Louis G. Mueller,
• Allen Chao,
• Embarek AlWedi and
• Fraser F. Fleming

Beilstein J. Org. Chem. 2021, 17, 1499–1502, doi:10.3762/bjoc.17.106

• etomidate [4] and the antileukemia agent nilotinib [5]. The outstanding and diverse bioactivity of imidazole-containing pharmaceuticals [6], as well as their role as ligands for transition metals [7], and organocatalysis [8], has stimulated an array of creative syntheses [9][10]. Among the numerous routes

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