Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• compound obtained using approaches for activating silent genes, Wang et al. discovered SF2768, a metabolite produced by Streptomyces thioluteus that chelates copper as a chalkophore [63]. However, it has been suggested that activation of secondary metabolism in actinomycetes may depend on various metals

• . Indeed, it has been reported that adding to the culture medium rare metals not normally used as medium components can activate secondary metabolite biosynthetic genes. For example, Kamijo et al. found that Streptomyces sp. YB-1 produced reddish-purple pigment(s) only in the presence of a rare earth metal

• , ytterbium (Yb), but not in the presence of other metals. Structural analyses revealed that this pigment is a type of naphthoquinone similar to nanaomycin (24) [64]. Furthermore, Tanaka et al. showed that low concentrations of the rare earth elements scandium (Sc) and/or lanthanum (La) markedly activate (2.5

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• to the employment of GO–CuBr without overshadowing its applications [113]. Shirini et al. utilized the polymer poly(4-vinylpyridine) (P4VPy) for the immobilization of nanoparticles in lieu of silica, due to the strong affinity of the pyridyl group towards metals and its ability to undergo hydrogen

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• -catalyzed asymmetric hydrogenation of indoles to synthesize chiral indolines has been widely studied (Scheme 1a) [21][22]. Representative examples include Ir- or Ru-catalyzed asymmetric hydrogenation of 2,3,3-trisubstituted 3H-indole [23][24]. Generally, these methods employ precious metals and/or

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

• relevant heterocycles in high efficiency [10]. The Chan–Lam coupling is considered a greener alternative to traditional C–N coupling reactions, as it can be carried out under mild reaction conditions (room temperature and short reaction times, etc.), plus it does not require expensive metals like Pd, being

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• to furnish trifluoromethylated dihyropyrido[1,2-a]indolones under mild conditions, without the need of photocatalysts or transition metals [28]. Results and Discussion We initialized our study by employing Ru(bpy)3Cl2·6H2O and Umemoto’s reagent to generate trifluoromethyl radicals via a photo

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• ., Yekaterinburg 620002, Russia Innovation Center for Chemical and Pharmaceutical Technologies, Ural Federal University, 19 Mira st., Yekaterinburg 620002, Russia Department of Medical Biology and Genetics, Ural State Medical University, 3 Repina st., Yekaterinburg 620028, Russian Sustainable Chemistry for Metals

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• ], Pd(II) [31][32][33], Pt(II) [34][35], Fe(III) [36][37], Cu(I) [38][39][40][41], Co(III) [42][43][44], as well as other metals, have been widely studied. In addition, methods involving Brønsted acids, alone or in presence of Lewis acids as co-catalysts, have been developed [45][46][47][48][49][50][51

Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

• Nedra Touj,
• François Mazars,
• Guillermo Zaragoza and
• Lionel Delaude

Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145

• -dithiocarboxylate zwitterions (Figure 2) [30][31][32][33][34][35][36][37][38][39][40][41][42][43]. These 1,1-dithiolate inner salts strongly bind main group elements and transition metals through various coordination modes. Indeed, we and others have already reported the synthesis of diverse metallic complexes

• metals. Details of these studies will be disclosed in a forthcoming publication. Various types of stable singlet carbenes and their acronyms. Various types of NHC·CS2 zwitterions and their coordination modes. ORTEP representations of zwitterions 4a (CAAC-Mes-Cy·CS2, top) and 4c (CAAC-Die-MePh·CS2, bottom

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• achieved using highly reducing metals, molecular reductants can potentially enable more selectivity, as required for the use of such reactions in the synthesis of molecules bearing various functional groups. In particular, Wanzlick dimers (C=C-bonded dimers of N-heterocyclic carbenes, Figure 1a, i) have

• electropositive metals and may be of use in more elaborate chemical transformations. Mechanism of dark reactions Doping of organic semiconductors by (Y-DMBI)2 dimers [18][39] or by various dimers formed by 18-electron sandwich compounds [18][40][41], as well as redox reactions of other dimers formed by organic

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• naphthazarin and triptycene units (Scheme 14) [48]. Naphthazarin derivatives are known to complex with boron moieties and metals to form electron-poor acene units. Through the Diels–Alder reaction involving dienophile 66, which was formed via the tautomerization of compound 65, and diene 67, compound 68 was

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• their structural stability, flexibility, or complexing ability with transition metals [6][7][8][9][10][11][12]. meso-Aryl-substituted dipyrromethanes or tripyrranes are the most commonly used starting materials in hexaphyrin syntheses [13][14][15][16]. Osuka et al. made significant contributions to the

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• utilities, there are still a few drawbacks associated with these photoredox reactions. One of the main limitations is the reliance on precious metals such as Ir, Ru, and Pd, or elaborate organic dyes that act as photosensitizers, which are either limited in abundance or require additional synthetic steps to

• decarboxylative alkylation reaction that was facilitated by the synergistic action of a cost-effective and easily accessible NaI/PPh3 catalyst system (Scheme 1). This system offered an alternative to the use of precious metals or complex organic dyes as catalysts. The developed NaI/PPh3-based system not only

• light irradiation at either 440 nm or 456 nm, and they occurred in acetone at room temperature, without the need for transition metals or organic dyes as photosensitizers. Interestingly, it was discovered that solvation played a vital role in the overall process. These findings shed light on the

Selectivity control towards CO versus H₂ for photo-driven CO₂ reduction with a novel Co(II) catalyst

• Lisa-Lou Gracia,
• Philip Henkel,
• Olaf Fuhr and
• Claudia Bizzarri

Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129

• ]. Among the most employed earth-abundant metal-based PS, Cu(I) complexes have the first place, not only in artificial photosynthesis, but also in a large variety of photo(redox)catalyses [12][13][14][15][16][17]. On the other hand, several complexes based on 3d transition metals, like manganese [18], iron

• [19][20][21], cobalt [22][23], and nickel [24][25], have been designed as CO2 reduction catalysts. This (supra)molecular approach is appealing for gaining a structure–property understanding with the goal of tunable and efficient activity. Among the 3d transition metals, cobalt is relatively abundant

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• oligo(ethylene glycol) segment. These hybrid systems constitute a broad group of compounds, including crowned porphyrins, crownphyrins, and calixpyrrole-crown ether systems forming Pacman complexes with transition metals. Their unique nature accustoms them as excellent ligands and hosts capable of

• metals. In this perspective article, the overview of both the early designs of porphyrin-crown ether hybrids, as well as the most recent advances in the synthesis and characterisation of this remarkable group of macrocyclic systems, are addressed. The discussion covers the strategies employed in

• of the ring and incorporated entities, they can present relative rigidity or flexibility [17]. The adaptable molecules of crown ethers render them excellent hosts for a wide range of alkali- or alkaline earth metals and organic guests with which they typically interact through hydrogen bonding

C–H bond functionalization: recent discoveries and future directions

• Indranil Chatterjee

Beilstein J. Org. Chem. 2023, 19, 1568–1569, doi:10.3762/bjoc.19.114

• the abstraction of intramolecular hydrogen atoms. Radical chemistry is a viable alternative to the two-electron process, involving C–H bond functionalization in the absence of any ligand and using low-cost redox-active metals (Fe, Cu, Mn, etc.) rather than heavy metals (Rh, Ir, etc.). Although radical

Lewis acid-promoted direct synthesis of isoxazole derivatives

• Dengxu Qiu,
• Chenhui Jiang,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2023, 19, 1562–1567, doi:10.3762/bjoc.19.113

• nitrite as a nitrogen-oxygen source, and solely using aluminum trichloride as the additive. This approach circumvents the need for costly or highly toxic transition metals and presents a novel pathway for the synthesis of isoxazole derivatives. Keywords: aluminum trichloride; Lewis acid; isoxazole

• derivatives; sodium nitrite; transition metals; Introduction The isoxazole derivatives not only exist in many natural products [1][2][3] and pharmaceutical intermediates [4][5][6][7], but also have great application values in organic synthesis [8][9] (Figure 1). In the past decades, many methods have been

• nitrogen source (Scheme 1, reaction 2). In 2017, Xu and co-workers [19] developed a copper-mediated annulation reaction to synthesize isoxazoles from two different alkynes. In fact, most methods mostly used highly toxic transition-metal catalysts such as copper metals. In order to develop cheaper and more

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• in DMF at 100 °C for 5 h [30]. We hypothesized that electron-withdrawing p-cyanophenyl azide 2b, would be better suited for optimizing the reaction conditions compared to the unsubstituted phenyl azide 2a. Taking a clue from the literature, we looked at transition metals that facilitate

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• . A number of excellent reviews on different aspects of NHC chemistry has been published during this period [12][13][14]. NHCs have been widely employed in homogeneous catalysis [12] and as ligands for the preparation of coordination compounds of different metals [13]. The M–NHC bond is relatively

• (I) complexes are frequently used to prepare NHC complexes of late transition metals [37]. As mentioned earlier, Diez-González et al. prepared some NHC–Cu(I) complexes, such as 69 through transmetallation by reacting [(SIPr)AgCl] 68 with the corresponding copper salt at rt (Scheme 23). However

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• compete with classic phosphorescent emitters that employ scarce metals such as iridium and platinum [7][8][9]. Since its first report in 2012 by Uoyama et al., 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) has been a benchmark TADF emitter due to its high quantum yields and excellent

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• interest in developing novel methodologies in this field of organic chemistry. Keywords: alkylation; cross-dehydrogenation coupling; ether; non-noble metals; Introduction Since the 1970s, organic chemists have developed many selective cross-coupling methods for the construction of C–C bonds, such as the

• overcome the shortcomings of the above coupling reactions, organic chemists have envisaged the construction of C–C bonds directly through C–H bond activation [5]. Fortunately, scientists have used various transition metals as catalysts to realize the activation of various types of C–H bonds, and have

• . Route b: the α-C(sp3)–H bonds are activated by a combination of transition metals and radical initiators to give the alkyl radicals, which are coupled with other radical receptors to afford the target product. Cu-catalyzed reactions Copper (common oxidation states are +I, +II and +III) has a

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• literature examples of nitrate oxidation of different transition metals, such as palladium. Control reactions further supported this proposal, including the inability of alternative Fe(III) salts (e.g., FeCl3) to form more than stoichiometric azide product in the absence of added nitrate. We believe this

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

• half potential (*E1/2 = −3.36 V vs SCE) even more negative than alkali metals including lithium, making it one of the most potent chemical reductants ever reported. Owing to this exceptional reductive redox power, hydrodehalogenation of various electron-poor and electron-rich aryl bromides and

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• considerable attention by organic chemists because of the strategic importance of this process as well as the ability to synthesize functionalized aromatic molecules in a straightforward way. Many organic name reactions have been discovered utilizing the C–H bond functionalization concept [1]. Metals were

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

• including transition metals and rare earth metals has been described and some other organometallic systems also were shown to have catalytic reactivity. Adopting this catalytic reactivity of organometallics and also the special bidentate nature of phosphinoamide ligands, in 2021, Chen and group [58

• metals inhibits the metal–chiral ligand coordination, thus making the C–H alkylation of pyridine substrates challenging. In addition, transition-metal-catalyzed enantioselective C–H alkylation reactions of pyridine still remain a great challenge. In this regard, in 2022, Ye and co-workers [60] reported

• iridium catalysis was achieved by Shi [61] in 2010 through an unusual meta-selectivity for the first time (Scheme 11a). To achieve meta-selectivity, the group has screened various transition metals and revealed that a silyl-iridium complex promoted the addition of meta-pyridyl C–H bonds to aldehydes 50

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• high potential for further optimization. Aerobic oxidation using transition metals instead of TEMPO was also investigated. Pd(OAc)2 (Table 1, entry 6) [42] and Cu(OAc)2 (Table 1, entry 7) [43], and Ni(OH)2 (Table 1, entry 8) [44] left the starting material 1a. Pd(OAc)2 led to moderate conversion, but