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

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

• Avanzada (ORFEO-CINQA) and Instituto de Síntesis Orgánica (ISO), PO Box 99, 03080 Alicante, Spain 10.3762/bjoc.17.192 Abstract A series of novel palladium(II) and nickel(II) complexes of multifunctionalized aroylaminocarbo-N-thioylpyrrolinates were synthesized and characterized by analytical and

• , 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

• results of its corresponding nickel(II) [18] and palladium(II) [19][20] complexes with the analogous tests obtained in the case of having a benzylic substituent at the same position. Also, DFT calculations are run in order to study the conformational analysis of the synthetized complexes. Results and

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

• rearrangement. Nickel(II)-catalyzed enantioselective rearrangement of ketol 3 to form the ring-expanded and chiral product 4. Enantioselective ring expansion of β-hydroxy-α-dicarbonyl 6 catalyzed by a chiral copper-bisoxazoline complex. Enantioselective rearrangement of ketols 9 and 12 and hydroxyaldimine 14

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• esterified pyridines 29 in moderate to high yield. It is worth noting that 1,3-enynes 28 bearing internal alkyne moieties were not tolerated as substrates. In 2016, Aïssa and co-workers reported a nickel-catalyzed [4 + 2]-cycloaddition of 3-azetidinones 30 with 1,3-enynes 31 for the synthesis of 3‑hydroxy

• -4,5-alkyl-substituted pyridines 33 (Scheme 11) [53]. The transformation involved a two-step sequence of successive reactions: Firstly, the nickel-catalyzed [4 + 2]-cycloaddition of 1,3-enynes 31 and N-Ts-substituted 3-azetidinone 30 afforded dihydropyridinones 32 in good yield. The next step involved

• chalcogenoamination. The derivatization of 5‑selenyl- and 5-sulfenyl-substituted nicotinates. The tandem reaction of nitriles, Reformatsky reagents, and 1,3-enynes. Nickel-catalyzed [4 + 2]-cycloaddition of 3-azetidinones with 1,3-enynes. Electrophilic iodocyclization of 2-nitro-1,3-enynes to pyrroles. Electrophilic

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

• potassium sodium tartrate solution (Rochelle salt) to furnish the aldehyde 5. Then, transformation of the 7-formyl into the 7-aminomethyl group proceeded via oxime formation, applying hydroxylamine hydrochloride in methanolic ammonia, followed by reduction with Raney nickel to yield the tritylated precursor

• ) hydroxylamine hydrochloride (21 mg, 0.300 mmol) was added. A clear solution was obtained shortly thereafter. The reaction was stirred for two hours at room temperature. Tetrahydrofuran (4 mL) and damp Raney-Nickel (approximately 200 mg) were introduced and the reaction was continued for one hour. The reaction

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

• metallaphotoredox catalysis enabled C‒H functionalizations with unique reaction pathways under mild reaction conditions. Given the relative earth-abundance and cost-effective nature, nickel catalysts for photoredox C‒H functionalization have received significant attention. In this review, we highlight the

• 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

• of synthetic routes for modern pharmaceuticals [21][22]. Over the past two decades, nickel has emerged as an attractive alternative to palladium due to its relative earth-abundance, less toxicity, and inexpensiveness. Despite the fact that the nickel-catalyzed cross-coupling reactions represent a

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

• ] cyclotrimerization reactions in the presence of nickel and cobalt catalysts [38]. First, they employed diyne 15 in the reaction with a series of alkynes (16) or nitriles (17) bearing a variety of functional groups including alkyl and alkene chains, hydroxy groups, and benzene and pyridine rings, to achieve the

• oxidative benzannulation reactions of 1-adamantoyl-1-naphthylamines with internal alkynes. Gold/bismuth-catalyzed cyclization of o-alkynyldiarylmethanes. [2 + 2 + 2] Cyclotrimerization reactions with alkynes/nitriles in the presence of nickel and cobalt catalysts. Cobalt-catalyzed [2 + 2 + 2

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

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

• obtained triazoles 178 were then transformed into the corresponding 5-aminotriazoles 179 by reduction with Raney nickel in MeOH at 60 °C. In addition, the further transformation of 5-aminotriazoles 179 into more complex derivatives, such as 180–183, was explored [68]. The Huisgen reaction of structurally

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• ] auxiliaries (Figure 1a). Besides, the cobalt(II)- [31] or nickel(II)-catalyzed [32][33], pyridine oxide (PyO)-directed tandem alkynylation/annulation was realized by Niu and Song et al., which also provided the 3-methyleneisoindolin-1-one scaffolds (Figure 1b). Notably, a sustainable cupraelectro-catalyzed

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

• C, which undergoes an oxidation process to generate carbocation D. A proton abstraction from D then affords the observed product. Cross-coupling reaction between unactivated olefins and alkyl halides under nickel catalysis The use of alkyl halides in transition-metal-catalyzed cross-couplings to

• ]. Nickel catalysis is a viable alternative for this kind of cross-coupling reactions due to its particular radical mechanism, instead of the common metal-oxidative addition to organohalides [102][103][104]. Examples of the coupling between primary, secondary, and even tertiary alkyl halides with

• olefins 84 as nucleophile partners and racemic secondary and tertiary α-bromo-N-protected β-lactams 83 under nickel catalysis, along with the chiral bis(oxazoline) ligand 85 and triethoxysilane (Scheme 32) [108]. Substrate structural variations on 84 had only a small impact on the reaction

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

• electrophiles to afford imidazoles. In situ cyclization to the imidazole is promoted by the conjugate acid, hexamethyldisilazane, which facilitates the requisite series of proton transfers. The rapid formation of imidazoles and the interchange of the anisylsulfanyl for hydrogen with Raney nickel make the method

• to substituted imidazoles. Raney nickel hydrogenolysis was effective in interchanging the C4 anisylsulfanyl group for hydrogen (Scheme 3); attempted lithium–anisylsulfanyl exchange [19] or palladium- [22] or nickel- [23] anisylsulfanyl cross coupling was not successful. Raney nickel reduction of 7f

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