Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• bonds. This protocol involves the visible light-assisted Sonogashira coupling of aryl bromides and terminal alkynes in the presence of the Co(C9H9NO2)3 complex as the catalyst (Scheme 34) [45]. This novel catalytic system provided 23 alkyne products in a substrate scope study using ethylene glycol as

• additive and K2CO3 as base in DMF under visible light irradiation. The reaction of Co(OAc)2·4H2O with 2-(hydroxyimino)-1-phenylpropan-1-one in EtOH resulted in the formation of the Co catalyst. The coupling strategy exhibited only poor activity by the use of pure Co salts and the reaction was promoted by

• -substituted bromobenzenes with phenylacetylene in the presence of Co(C9H9NO2)3. Possible mechanism for the visible light-assisted cobalt complex-catalyzed Sonogashira coupling. (Reproduced with permission from ChemCatChem. 2018, 10, 758–762.) Sonogashira cross-coupling of aryl halides and phenylacetylene

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• of the material (Figure 3a and Figure 3b). The TEM images showed agglomeration of spherical NPs, leading to the formation of multiple scaffolds. In the SEM images, the presence of spheres of 40–60 nm was clearly visible (Figure 3c and Figure 3d). Often, these small NPs were agglomerated to form

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

• product (Table 1, entry 5). However, tertiary amines with a benzyl group reacted very slowly and afforded the expected product in moderate yield (Table 1, entry 6). The reason for the incompatibility of tributylamine towards this method has yet to be explored. A synthesis of allylic cyanides via visible

• conditions, readily available reagents, lower catalyst loading, and the use of cost effective atmospheric oxygen and visible light are the most attractive characteristics of this reaction. Xu et al. in 2016 discussed the deboronative cyanation of alkyltrifluoroborates using [Ru(bpy)3](PF6)2 as the photoredox

• catalyst [41]. This method provides an efficient pathway to 1°, 2°, and 3° alkyl nitriles using p‐toluenesulfonyl cyanide (TsCN) in CH2Cl2/H2O under visible-light irradiation (Scheme 17). 1‐Acetoxy‐1,2‐benziodoxol‐3‐(1H)‐one (BI‐OAc) was chosen as the oxidant and TFA as the additive in this method. A lower

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

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• structure stacking diagram of the CPE@Q[8] host–guest complex along the c-axis. It can be clearly seen that small hexagonal holes are formed between the complexes, which are expected to have potential applications in molecular adsorption and drug delivery. UV–visible spectroscopy The interaction between Q[8

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

• chloroform solutions were measured with a Cary50 Eclipse Fluorescence Spectrophotometer (excitation/emission; slit 2.5 mm). All spectra can be found in Supporting Information File 1 (Figures S2–S7). Photostability assays were performed using white-light LED array system irradiation (visible range) at 25 mW

A tribute to Carsten Schmuck

• Jochen Niemeyer,
• Ivo Piantanida and
• Thomas Schrader

Beilstein J. Org. Chem. 2021, 17, 2795–2798, doi:10.3762/bjoc.17.190

• had very intensive international collaborations with many group leaders all over the world, easily visible from scientific publications and from a recent review article [1]. Moreover, Carsten also took a prominent part in several formal EU collaboration schemes, giving a notable contribution to the

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

• -planar geometry, thereby resulting in a shorter excited state lifetime compared with ruthenium and iridium-based photocatalysts and thus limiting the application of CuI complexes to visible-light-mediated organic syntheses [22][31]. Homoleptic CuI bisphenanthroline complexes were designed with

• homolysis to produce CuI species and radical intermediates. These intermediates can initiate productive organic transformations [39]. 2.1 Visible-light-mediated Cu(I) catalytic cycle Upon the absorption of a photon (Scheme 4), CuILn forms a singlet MLCT state, which subsequently yields the excited triplet

• , in path b (a rebound cycle), CuI* is trapped after a SET by the radical intermediate to generate a CuIII species, which undergoes ligand exchange with the nucleophile and reductive elimination to produce the target product and the regenerated CuI catalyst [37][38][40]. 2.2 Visible-light-mediated Cu(I

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• visible light photoredox-catalyzed cyclizations also afforded phenanthridines (Figure 2, reaction 3) [11]. Inspired by the Rodrıguez and Walton approach, we sought to synthesize the nitrogen analogue of an angucycline known as phenanthroviridone 6, [12] from oxime 7 (Scheme 1). Based on the results

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• associated with antineurodegenerative diseases. Experimental General experimental procedures. Optical rotations were measured on a JASCO P-2000 polarimeter. IR spectra were acquired with a JASCO FT/IR-4600 spectrometer. UV spectra were obtained on a Shimadzu UV-1601 UV–visible spectrophotometer. NMR spectra

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

• salts are generated in situ and converted to radicals through irradiation with visible light. Reaction products precipitate from the solvent, eliminating the need for purification and thus providing a novel green method for the synthesis of versatile bis-electrophiles. Keywords: benzoquinone; diazonium

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

• binding of biorecognition molecules on a PEG nanoparticle to its target only works when the PEG chain length is less than the polymer chain to which the ligand is attached. Otherwise, the long PEG chain will intercept ligand binding [50]. It is also reasonable to think that TPP is barely visible on the

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

• developments in the field of photoredox nickel-catalyzed C‒H functionalization reactions with a range of applications until summer 2021. Keywords: C–H activation; functionalization; nickel; photocatalysts; photoredox; visible light; Introduction During the last decades, transition-metal-catalyzed

• developments, which enables a diverse range of previously inaccessible organic transformations in milder reaction conditions [31][32][33][34][35][36][37][38][39][40]. Here, by absorbing visible light, a photocatalyst can function as a single-electron redox mediator through an oxidative or reductive quenching

• were found to be suitable to achieve the transformation in satisfactory yields under visible light irradiation (Scheme 2). The authors hypothesized that the key α-nitrogen carbon-centered radical 5 could be generated via a photoredox-driven N-phenyl oxidation and α-C–H deprotonation sequence from

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

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• conversions. To prevent the use of harmful UV light, different longer-wavelength photoinitiating systems (PISs) were proposed, e.g., blue light in dental materials [1][2]. Many PISs were developed for visible light, but much less studies are focused on the polymerization using near-Infrared (NIR) sources [3

• obtained with low energy and a moderate device cost contrary to thermal solutions; ii) mild irradiation conditions: safer and cheaper systems; and iii) the curing of thick and/or filled systems that cannot be addressed with UV or even visible-light-sensitive systems. Thus, the NIR curing of thick and

• (wavelength of the irradiation used). The visible–NIR spectra of IR 813 (Scheme 2) considered as a reference is given in Figure S1 in Supporting Information File 1. NIR polymerization initiating ability Due to the good NIR absorption properties, the proposed dyes have been tested as photoinitiators in

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

• more effective in the CM transformations. Note, that first-generation catalyst HG-1 did not afford cross-metathesized products. Our data allows to summarize some clearly visible general trends. First of all, most CM reactions of compounds (±)-4 and (±)-5 were only slightly regioselective

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• employed palladium(II) acetate and visible light under O2 in the reactions between ethyl acrylate (192) and substituted diaryl carboxylic acids 193, to produce anthraquinones 194 in low to moderate yields (30–68%). In a direct comparison with the methodology proposed by Hong for the synthesis of

• anthracenes, previously shown in Scheme 7 [41], the key to obtaining anthraquinones was the photooxidation induced by visible light, which afforded the substituted anthraquinones 194. In this case, the effect of the aromatic ring substituents also affected the yield of the anthraquinones, as can be seen from

• multicomponent reactions employing 2-hydroxy-1,4-naphthoquinone (186), β-naphthol (181), and aromatic aldehydes. Synthesis of substituted anthraquinones catalyzed by an AlCl3/MeSO3H system. Palladium(II)-catalyzed/visible light-mediated synthesis of anthraquinones. [4 + 2] Anionic annulation reaction for 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

• has been selectively feasible without activating a C(sp2)–H bond in the arene moiety. Verma and co-workers [91] have reported the use of VO(acac)2 immobilized over graphitic carbon nitride (VO@gC3N4) under visible light irradiation to perform a photocatalytic C–H activation of arene methides and

• are crucial. In 2018, Ackermann and co-workers described a novel room temperature C–H arylation by using a continuous visible light photo-flow technique, allied with a manganese photocatalyst CpMn(CO)3 [142]. The new flow protocol enabled the synthesis of several arene- and heterocyclic-based

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• , azidated N-protected memantine 13a was successfully generated by employing electricity and visible-light irradiation in the presence of a Mn catalyst. High regioselectivity was observed at tertiary or benzylic positions (see 13a–c). For commercially available drug derivatives, methyl esters of ibuprofen

• excluded. This late-stage process by Mn catalysis, electrochemistry, and visible-light catalysis exhibits high value as a sustainable tool to investigate problematic synthetic transformations. Recently, the Ackermann group disclosed a convenient manganese-catalyzed late-stage C–H azidation of bioactive

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• ; aldehydes; cerium; oxidation; ketones; visible light; Introduction The selective oxidation of alcohols to carbonyl compounds [1][2] is an important process for producing a wide range of value-added fine chemicals [3][4][5][6]. In the traditional oxidation process stoichiometric amounts of oxidants such as

• acting as the terminal oxidant [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Most aerobic oxidation reactions utilize either metal complexes and nanoparticles or persistent radical reagents as catalysts [21]. In the past ten years, visible light-induced

• generating oxygen-centered radicals, that lead to carbon-centered radicals through intra/intermolecular hydrogen atom transfer (HAT) processes, radical decarboxylative or radical deformylation [57][58][59]. In continuation of our research interest on visible-light-driven cerium photocatalysis [59][65], we

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• may be due to the low hole conductivity, a decrease in the HOMO level of the polymer, and a narrower band gap of visible light absorption [51]. Within the framework of the study of the prospects for polymer derivatives of isoindigo in organic photovoltaics and avoiding the use of the fullerene

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• naphthoquinone-derived products and low-intensity bands in the visible region (≈400 nm) for the anthraquinone series. Keywords: [3 + 2]-cycloadditions; fluorinated compounds; fused pyrazoles; N-heterocycles; nitrile imines; 1,4-quinones; Introduction The 1,4-quinone scaffold belongs to the most important

• absorption in the visible range at ≈410 nm and medium-intensity absorption between 310–340 nm. In the latter region, a significant hypsochromic shift of the maxima with increasing electron-withdrawing character of the substituent X could be observed (Figure 3). Remarkably, the 1,4-anthraquinone-derived

• products 9i, 9k, and 9l exhibit two overlapping absorption bands in the visible range with maxima at λmax ≈ 400 nm and ≈ 425 nm, respectively. Conclusion The presented study demonstrated that 1,4-quinones undergo efficient [3 + 2]-cycloadditions with in-situ-generated electron-deficient

Substituted nitrogen-bridged diazocines

• Pascal Lentes,
• Jeremy Rudtke,
• Thomas Griebenow and
• Rainer Herges

Beilstein J. Org. Chem. 2021, 17, 1503–1508, doi:10.3762/bjoc.17.107

• makes them promising candidates for applications in photopharmacology. The halogen substituents allow further functionalization via cross-coupling reactions. Keywords: bridged azobenzene; diazocine; photopharmacology; photoswitch; triazocine; visible light switch; water-soluble switch; Introduction

• ) with light in the visible region [1]. Moreover, the Z-boat configuration is the thermodynamically stable isomer [2][3][4][5][6][7][8][9]. The latter property (i.e., the inverted stability compared to azobenzenes) makes them promising candidates for applications in photopharmacology. In the majority of

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature

• Fabian Rami,
• Jan Nowak,
• Felix Krupp,
• Wolfgang Frey and
• Clemens Richert

Beilstein J. Org. Chem. 2021, 17, 1476–1480, doi:10.3762/bjoc.17.103

• -crystals as more and more of the DCM evaporated. Changes in the content of guest molecules without loss of macroscopically visible crystallinity have been observed before [13]. Independent of what the pathway to co-crystallization was in the present case, the slow crystallization with solvent, as compared