Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• ]. Behrouzi et al. reported the electrochemical hydrogenation of carbonyl and amido compounds using nickel electrodes and water as the proton and electron source [42]. Furthermore, the carbonyl and amido compounds used in these electrochemical hydrogenation studies are more structurally similar to organic

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• ], Liu [35], and Yang [36] achieved similar transformations through visible-light photocatalysis. In addition, Guo [37][38] improved the protocol by using low-cost nickel and iron catalysts. However, most of these advancements mainly relied on the excellent redox potential manipulation of cyclic oxime

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

• DFT calculation, a plausible mechanism (Scheme 10b) has been proposed. Initially, a reversible ligand-to-ligand H-transfer process occurs for C–H activation between the intermediates 46 and 47. Next, isomerization of the η1-allyl complex 47 forms the η3-allylic nickel complex 48, which on reductive

• nickel Lewis acid catalyst with amino pendant linked NHC complex (Scheme 21). In addition, the authors were able to isolate the bimetallic intermediate structure η2,η1-pyridine–Ni(0)–Al(III) complex 112, as a support for their mechanism for the para-C–H functionalization. They further investigated the

• sterically bulky additive MAD coordinates to the pyridine nitrogen, which pushes the tethered alkene close to the nickel center subsequently providing the intermediate 201. Then, the C–D bond on cleavage via oxidative addition of Ni(0) forms the Ni–D species 202 which after anti-Markovnikov hydronickelation

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

• yield proved to be good to excellent and sterically hindered aryl rings were tolerated. This method was applied by Huang et al. [74] to prepare a series of fluorescent compounds in excellent yield. Copper- and nickel-catalysed arylation were reported as alternatives to the Pd-catalysed arylation of 1a

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• benzyl fragment was observed. This indicated that H-2 is located on the same side of the nickel coordination plane as the benzyl substituent at the proline nitrogen atom, leading to the ʟ-configuration of the α-amino acid stereocenter. Notably, the major stereoisomer of all thiolated compounds (RCysNi)L7

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• ][19][20][21][22][23][24][25][26][27]. In this section, we summarize recent progress in Ni, Fe, Cu, and Co-catalyzed domino reactions of strained bicyclic alkenes. Nickel-catalyzed reactions Without close inspection, nickel might seem like the peculiar younger sibling of palladium within the field of

• transition-metal catalysis. Nickel lies directly above palladium in the periodic table, as such, it readily performs many of the same elementary reactions. Because of their reactive commonalties, nickel is often seen as the budget-friendly replacement; however, this misconception will clearly be refuted in

• this section, showcasing several diverse nickel-catalyzed domino reactions. In 2001, Rayabarapu and co-workers investigated the Ni-catalyzed ring-opening/cyclization cascade of heterobicyclic alkenes 1 with alkyl propiolates 2 for the synthesis of coumarin derivatives 3 (Scheme 1) [28]. The reaction

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• °C [34] (Scheme 8). Further, nickel derivatives 44b–48b were also obtained from their zinc analogues by demetallation with concentrated HCl and metalation with nickel acetate. The preliminary photophysical results revealed a significant intramolecular energy transfer between the porphyrin core and

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• –Hiyama–Kishi (NHK) reaction is an interesting coupling reaction involving the addition of a halogeno derivative (either bromide or iodide) to an aldehyde in the presence of nickel and chromium salts, typically NiCl2/CrCl2, generating an alcohol. In its original version, the stereochemistry of the adduct

• ). Interestingly, the reaction was carried out under UV irradiation and in the presence of catalytic nickel diiodide allowing formation of the expected compound in 63% yield [67]. 4.2 SmI2-mediated ketyl addition: discussion around pleuromutilin scaffold access Despite the promising results of the SmI2-mediated

• (Scheme 30). 4.3 Nickel-catalyzed reductive cyclization: mutilin and pleuromutilin C12-epimers access In view of maximizing the scope of accessible pleuromutilin epimers from one single synthetic pathway, Herzon’s group reported a modular and convergent route, where the eight-membered ring was built

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• chemoselective and stereospecific mild hydrodesulfurization with Raney nickel in acetic acid affords the target compound 59 as a single Z-diastereomer. Interestingly, glacial acetic acid proved to be the only solvent that could avoid both undesired overreduction and cis–trans isomerization of the alkene bond. It

• . This was required to avoid undesired hydrogenation of both the vinyl and the cyclopropane moieties, which both proved sensitive to the action of Raney nickel. A particularly troublesome episode that demonstrates the problems one can encounter in dithiane desulfurizations, was encountered in our labs

• controlled alternative for the often troublesome, but nevertheless highly chemoselective hydrodesulfurization with Raney nickel would be a highly valuable addition to the organic synthesis tool box. Few good or general alternatives for this method seem to exist [114], and for very sensitive substrates

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• nickel-mediated decarboxylative Giese reactions and decarboxylative radical zinc-mediated cross-coupling reactions of redox-active esters, established from previous works of the group [27][28], for the key C–C bonds of the diverse congeners. To this end, a hypothetical intermediate 3 was envisioned for

• allylation using achiral H-PHOX followed to produce 16, without being isolated. From this point of divergence, Baran’s group managed to reveal the requisite phthalimide carboxylates for each precursor of the diverse natural products and transformed it carrying out Giese reactions or nickel-catalyzed radical

• an electrochemical method to provide the desired coupling towards 56 in 62% yield. Radical reduction by Mn(dpm)3 afforded stypodiol (57) after BBr3-mediated deprotection. Nickel-catalyzed coupling under a Weix procedure [31] was selected in order to elaborate the cores of taondiol (53) and chevalone

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• differed from the above path by leaving the hydroxy group of all intermediate 4-hydroxypyridine derivatives 12–15 unprotected [19]. Moreover, instead of azo coupling or nitroso formation, a simple nitration protocol with nitric acid to give the nitro derivative 13 and subsequent reduction with Raney nickel

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• ][25][26]. These catalytic cross-coupling reactions tend to follow similar pathways to the Michaelis–Arbuzov reaction, with the inclusion of a catalytic intermediate step. A number of suitable catalysts have been identified, ranging from nickel(II) bromide and nickel(II) chloride, to palladium(II

• , respectively), which allows for reactions to be run at high temperatures, thus enhancing the rate of the reaction. While the reaction mixture is refluxing, the alkyl phosphite is added in several small portions. The work we present differs from the conventional nickel-catalyzed cross-coupling reaction in two

• simplification of the workup procedure. Second, there is no dilution of the reaction mixture, which lends itself to an increased reaction rate. Contrary to the conventional method, this alternative method starts with the nickel(II) precatalyst and the alkyl phosphite, triisopropyl phosphite in our case, being

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• and scalable reaction conditions. Here, we report a continuous-flow approach to metallaphotoredox catalysis using a heterogeneous catalyst that combines the function of a photo- and a nickel catalyst in a single material. The catalyst is embedded in a packed-bed reactor to combine reaction and

• catalytic approaches [9]. Especially the combination with other transition metal catalysts (metallaphotoredox catalysis), such as nickel complexes, resulted in a vast number of new methods to achieve cross-couplings under mild conditions [10]. However, the conditions of these methods are often hard to

• combination of solid photocatalysts (i.e., semiconductors) and homogeneous nickel complexes are feasible, but the fact that the nickel complex is in solution reduces the benefits of packed-bed reactor types [19][23][24]. Recently, several bifunctional heterogeneous catalysts that combine the photo- and the

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• , 20 mM imidazole, pH 8.0). After ultrasonic cell crushing, the cells were centrifuged at 24,000 rpm for 60 min to remove cell fragments. The supernatant was filtered through 0.22 μm of the filter membrane and then loaded into the nickel column of the rebalanced lysate (HisTraqTM FF, GE Healthcare

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• oxidation of BF4− was required as the counter electrode reaction, and 10% of methanol was added to the anolyte solution. In this case (Table 1, entry 2) 13% of thione was obtained and the electrode did not show any signs of consumption. The same yield (13%) was obtained using nickel as cathode material

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• of up to 0.35 kg/h for enone 4. In the second step, the obtained 4-aryl-3-buten-2-ones 3 and 4 are selectively hydrogenated in flow using a packed-bed reactor with Raney nickel as catalyst affording raspberry ketone (5) in 91% yield and raspberry ketone methyl ether (6) in 94% yield, respectively

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• ferromagnetic or ferrimagnetic nanoparticles into these materials. For this purpose, superparamagnetic iron oxide nanoparticles (SPION) are most commonly used, of which the main forms are magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3). Although cobalt and nickel are also highly magnetic materials

• temperature control can be ensured, e.g., by IR pyrometers. 2.2 Application of trickle bed reactor systems for isopulegol production Berenguer-Murcia et al. [25] developed a near isothermal micro trickle bed reactor operated by radiofrequency (RF; 300 kHz) heating of nickel ferrite particles (110 µm

• ) deposited in the fixed bed. To achieve near-isothermal conditions at a reactor length of 50 mm, at least three heating zones were set up. The fixed bed was composed of alternating catalyst and heating zones. The heating zones consisted of a mixture of nickel ferrite particles and glass spheres with a

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• energies [53], however, it should be sufficient for brief analysis. Procedures and product characterization 4,6-Bis[3,6-di(tert-butyl)-9H-carbazol-9-yl]-5-methylpyrimidine (1). Compound 1 was synthesized in a manner similar to [30]. A mixture of compound tCbz-mPYR (90 mg, 0.13 mmol, 1 equiv), Raney nickel

• (270 mg, 3 equiv by mass), prepared before reaction according to [54], and methanol (3 mL) were placed in a screw-cap vial equipped with a magnetic stirring bar. The reaction mixture was heated at 90 °C under stirring for 2 h. Then, Raney nickel was filtered off and washed with hot chloroform. The

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• -stereocontrolled ring-opening reactions of oxa- and azabicyclic olefins with dialkylzinc reagents catalyzed by a nickel compound (Scheme 1) [60]. The reaction was entirely stereoselective; however, unsymmetrical OBDs 5 produced mixtures of regioisomers 6 and 7. In the same year, Hill and co-workers published a

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

• bare chitosan was carried out, and the spectrum exhibited characteristic peaks for the O–H and N–H stretching vibrations in the range of 3300–3400 cm−1 (Figure 1b). For the chitosan-supported nickel catalyst, the band around 3400 cm−1 became much sharper and stronger compared to bare chitosan (Figure

• similarity of the two spectra may have been due to the low content of nickel in the catalyst. To understand the crystallinity of the material, we carried out a powder XRD (PXRD) analysis (Figure 2). Chitosan, in general, gives rise to a characteristic, partially crystalline phase by virtue of intramolecular

• dry conditions. As such, we observed different particle sizes in the SEM and TEM analyses. Since small particles of 40–60 nm were present consistently throughout the grid, they fell within the definition of NPs. The EDX study of the catalyst (Figure 4) confirmed the presence of nickel in this sample

Earth-abundant 3d transition metals on the rise in catalysis

• Nikolaos Kaplaneris and
• Lutz Ackermann

Beilstein J. Org. Chem. 2022, 18, 86–88, doi:10.3762/bjoc.18.8

• industries as one of the most powerful methods for molecular assembly. With regard to the cost of goods and the allowance of trace metal impurities in medicinally relevant compounds, 3d transition metal complexes, such as those of iron, copper, cobalt or nickel, represent exciting, more sustainable

• nickel-catalyzed C–H functionalization [10]. Iron complexes are typically cost-effective and nontoxic, and therefore, their use in domino processes represents an outstanding prospect for sustainable organic syntheses [11]. Directed C–H activations have been developed as increasingly amenable tools for

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• )phenyl]ethylene in acetic acid efficiently produced 4-vinyl-1,2-naphthoquinones 55 and 4-aryl-1,2-naphthoquinones 56a,b, respectively, under nickel(II) catalysis, forming a C–C bond (Scheme 16) [103]. When the reaction was carried out in 10% aqueous methanol solution at room temperature for 5 hours, 56b

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• strategy for aldehyde C–H activation. The acyl radicals generated in this step were arylated with aryl bromides through a well stablished nickel cross-coupling methodology, leading to a variety of interesting aryl ketones in good yields. We also performed computational calculations to shine light in the

• through this step were used in a well-stablished nickel-catalyzed cross-coupling reaction [19][27][28][29][30] with aryl bromides as a proof of concept, leading to the synthesis of aryl ketones. We also present computational calculations of the HAT reaction step with the DABCO radical cation as the

• addition experiment with methyl acrylate (Supporting Information File 1, Table S5), along with the strong dependence of aryl bromide electronics on the yield indicate the protagonism of the nickel-aryl bromide system. We hypothesized a HAT step by the bromine radical, generated by nickel complex photolysis

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

• ], nickel [20][21][22][23], and iridium [24][25][26][27] have taken center stage when it comes to the development of synthetic methodology. Although these late TMs have contributed enormously to the various fields of organic, inorganic, and organometallic chemistry, growing concerns regarding their economic