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

Copper-catalyzed N-arylation of amines with aryliodonium ylides in water

• Kasturi U. Nabar,
• Bhalchandra M. Bhanage and
• Sudam G. Dawande

Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76

• .19.76 Abstract Copper sulfate catalyzed an efficient, inexpensive, and environment-friendly protocol that has been developed for N-arylation of amines with 1,3-cyclohexadione-derived aryliodonium ylides in water as a green solvent. Aromatic primary amines substituted with electron-donating as well as

• bond formation. However, these methods suffer from limitations such as moisture sensitivity, the requirement of specific ligands, and the use of expensive palladium catalysts [17]. Also, Chan Lam, Evans, and other research groups have developed copper-catalyzed C–N bond formation reactions by careful

• tuning of the ligand and base combinations [18][19]. Thereafter, copper-catalyzed C–N bond-formation reactions have experienced unprecedented development due to mild reaction conditions and the low cost of copper salts [20][21][22]. On the other hand, hypervalent iodine reagents serve as versatile tools

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• at 60 °C (Scheme 15). Among the different solvents used to optimize the reaction conditions, H2O turned out to be a better and greener solvent compared to other organic solvents (e.g., MeCN, C6H6, CH2Cl2, THF, EtOH, EtOAc). Deng et al. [69] brilliantly described an expedient copper-catalyzed Clauson

• synthesis and proposed mechanism of N-substituted pyrroles 29. Magnetic nanoparticle-supported antimony catalyst used in the synthesis of N-substituted pyrroles 31. Iron(III) chloride-catalyzed synthesis of N-substituted pyrroles 33. Copper-catalyzed Clauson–Kaas synthesis and mechanism of pyrroles 35. β-CD

• -SO3H-catalyzed synthesis and proposed mechanism of pyrroles 37. Solvent-free and catalyst-free synthesis and plausible mechanism of N-substituted pyrroles 39. Nano-sulfated TiO2-catalyzed synthesis of N-substituted pyrroles 41. Copper nitrate-catalyzed Clauson–Kaas synthesis and mechanism of N

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

• 1,4-dioxane the transformations performed the best (Table 1, entries 3–5). A series of copper catalysts such as CuI, CuCN, and Cu2O was screened, in which some showed good catalytic activity (Table 1, entries 6–9), and Cu2O was identified as the most effective catalyst for the desired transformation

• Scheme 5. Under the promotion of the base, cyclobutanone oxime preliminarily reacts with SO2F2, generating the activated precursor fluorosulfonate, which further reacts with the alkene 2a in the presence of the copper catalyst under Ar atmosphere for 9 h (Scheme 5a). The corresponding product was

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• frameworks (MOFs) [16][54] has allowed the dynamics of the different counterparts in the solid state, as well as some advanced applications [55][56][57][58][59][60][61]. Berna and colleagues prepared a copper-organic framework (UMUMOF-(E)-3) containing the interlocked fumaramide (E)-3 as the organic ligand

• (Figure 3a) [62], forming rhombohedral grids connecting four different rotaxane derivatives to distinct copper-paddlewheel clusters (Figure 3b). Upon irradiation at 312 nm using a photoreactor equipped with UV lamps, 20% of the fumaramide stations were photoconverted into the corresponding intertwined

• the solid structure of UMUMOF-(E)-3 showing a rhombohedral metallogrid; and (c) cartoon representation of the operation mode of UMUMOF-(E)-3 as a molecular nanodispenser [62]. Colour key of the solid structure: light blue = carbon atoms; purple = nitrogen atoms; red = oxygen atoms; and grey = copper

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

• and the base the initial direct C–H activation of the ylide 12 gives the copper pyridinium ylide 15. The latter reacts with the diazo compound formed through reaction of hydrazone 13 with the base to give the copper–carbene species 16. Then, the intermediate 16 undergoes a Cu–carbene migratory

• and 163 through a two-fold C–H activation under palladium catalysis. Silver carbonate and 2,6-lutidine were found to be an effective base and ligand, respectively, for providing the desired products 164 and 165 in good yields (Scheme 31). In 2015, an economic route for copper-catalyzed biaryl coupling

• plays a role as an activator and is subsequently eliminated via deoxygenative elimination furnishing the C-2-functionalized pyridines 167. The reaction mechanism (Scheme 32b) involves the initial C–H-cupration of 166 producing an oxazolyl–copper intermediate 168. Nucleophilic addition followed by C–H

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

• . From the viewpoint of application to pharmaceutical manufacturing, the residual amount of copper must be controlled according to ICH Q3D [41]. Iron and zinc have low toxicity and are not listed in ICH Q3D. In comparison with the initial reaction rate of 60 min, Fe(NO3)3/TEMPO in Table 1, entry 3 shows

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

• disorders) [16] (Figure 2). 10,11-Dihydrodibenzo[b,f]azepine-based ligand 7 and a methyl analogue thereof are known to form pincer complexes with Pd, Ir, Rh and Ln [5], whereas a copper(II) wagon wheel complex of 8 was reported in a molecular organic framework (MOF) (Figure 3) [6]. 4,4'-(5-(Pyridin-2-yl

• copper-catalysed oxidative conditions to effect the transformation to 30 and 31. 2.3 Ring expansion from N-arylisatins Elliott et al. [47] reported the four-step synthesis of fluorinated 5H-dibenzo[b,f]azepine 38 from N-arylisatin 34 via Wagner–Meerwein rearrangement of 9-acridinemethanol 37 [43] (Scheme

• synthesised via a copper-catalysed Ullman-type coupling or a palladium-catalysed Buchwald–Hartwig amination (Scheme 9). Performing the rearrangement at high temperatures resulted in the undesirable formation of acridine byproducts 44. Cleaner reaction profiles could be obtained at a lower temperature (100 °C

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• oligomers 5 can be synthesized by a Glaser oxidative dimerization of monomers 6 (Scheme 1). The obvious route for the synthesis of the latter is the sequential alkynylation of 2,7-diiodonaphthalene 8. In accordance with this strategy, diiodide 8 was cross-coupled with copper(I) arylacetylides (Castro

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• measured on a high-sensitivity fluorescence spectrometer HORIBA Fluorolog-3. TEM experiments. The morphology and size of TBTQ-C6/CS-TPE nanoparticles were studied by use of a Talos F200X G2 field emission transmission electron microscope (TEM). The sample solution was dropped on a copper net and then dried

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• all possess helpful and, to an extent, specific reactivity characteristics. Interesting boron and silicon enolates can be generated by asymmetric conjugate boration [16], or silylation [17]. From several potentially catalytically active transition metals, copper combines beneficial properties for both

• benzaldehyde (51) (Scheme 13a). Related to this work, Feringa´s team realized also the conjugate addition to chromone (53) [44]. The enolate was again trapped with benzaldehyde in an aldol reaction (Scheme 13b). Naphthol derivatives 55 bearing an α,β-unsaturated ester group undergo a copper(I)-catalyzed

• asymmetric conjugate addition. The magnesium enolates 56 then participated in a copper(II)-mediated intramolecular oxidative coupling to afford benzofused spirocyclic cycloalkanones 57 (Scheme 14) [45]. Our team became interested in domino reactions of metal enolates generated by Cu-catalyzed asymmetric

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• difluoromethylphosphonate groups at the ring might be possible by using our newly developed bench-stable diazo reagent CF3C(N2)CF2P(O)(OEt)2. Therefore, we report herein our preliminary results toward this goal via copper iodide-catalyzed cyclopropanation reaction of an acceptor carbene precursor with selected terminal

• surprise, the application of Rh2(OAc)4 did not lead to the desired product neither in dichloromethane nor in toluene (Table 1, entries 1 and 2). Switching the catalyst to copper(I) iodide in refluxing DCM, did not result in the formation of product 6a, as well (Table 1, entry 3). However, when CuI was used

• amino group to the copper centre of an intermediately produced metallocarbene, thus favouring the formation of one diastereoisomer of 7g [50]. In addition, the cyclopropanes 7a–g were always obtained as mixtures of two diastereoisomers in different ratios and all attempts to separate them using column

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

• final ring-opened adduct 37. Copper-catalyzed reactions In 2009, Pineschi and co-workers explored the Cu-catalyzed rearrangement/allylic alkylation of 2,3-diazabicyclo[2.2.1]heptenes 47 with Grignard reagents 48 (Scheme 8) [41]. The reaction is thought to proceed via the Lewis acid-catalyzed [3,4

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• incorporation of the SCF3 residue on various molecules has known a tremendous expansion [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113]. Copper catalysis: In 2012, Daugulis and co-workers reported the copper

• -metal-catalyzed dehydrogenative 2,2,2-trifluoroethoxylation reactions have been reported. In 2021, the palladium-catalyzed ortho-2,2,2-trifluoroethoxylation of 3-arylcoumarins was depicted by the group of Kumar (6 examples, up to 69% yield) [162]. Further developments unveiled the use of copper

• catalysts for such functionalization. In 2013, the group of Daugulis described the copper-catalyzed ortho-2,2,2-trifluoroethoxylation of a 3-trifluoromethylated benzamide derived from 8-aminoquinoline, giving the corresponding product in 73% yield [149]. The group of Baidya showed that the dehydrogenative

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• , Germany 10.3762/bjoc.19.34 Abstract A protocol for the mechanochemical synthesis of copper(I)/N-heterocyclic carbene complexes using cheap and readily available K3PO4 as base has been developed. This method employing a ball mill is amenable to typical simple copper(I)/NHC complexes but also to a

• sophisticated copper(I)/N-heterocyclic carbene complex bearing a guanidine moiety. In this way, the present approach circumvents commonly employed silver(I) complexes which are associated with significant and undesired waste formation and the excessive use of solvents. The resulting bifunctional catalyst has

• been shown to be active in a variety of reduction/hydrogenation transformations employing dihydrogen as terminal reducing agent. Keywords: ball mill; bifunctional catalysis; catalytic hydrogenations; copper; mechanochemical synthesis; N-heterocyclic carbenes; Introduction Prominent goals of green

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

• connect two diverse moieties in a single framework. Therefore, this review focuses on the synthesis and photophysical studies of β- and meso-substituted and 1,2,3-triazole-fused porphyrin conjugates. All of the porphyrin conjugates discussed here are synthesized via a copper(I)-catalyzed Huisgen 1,3

• connect a porphyrin with a chromophoric group. Among these, the copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction [1][2] of azides with terminal alkynes is a popular and well established process to link a porphyrin with other moieties via 1,2,3-triazole group [3] (Figure 1). The term “click

• ] exploited the concept of “click chemistry” for the construction of β-substituted-triazoloporphyrins 3a–c in 65–95% yield by the reaction of β-azidotetraphenylporphyrins 1 with various arylalkynes 2a–c via copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction in DMF at 50 °C in the presence of CuSO4

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• to iodide and bromide were performed giving the salts 10a and 10b in excellent yields [27]. A copper-catalyzed iodination gave the diiodinated product 11 in quantitative yield [42]. Finally, N-methylation of 5aa was performed, to yield the dicationic salt 5av in 56% yield without decomposition of the

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

• polyene 14 (prepared in two steps) in multigram quantities [23]. The reaction employed a divided cell with substoichiometric amounts of magnesium(II) acetate (0.5 equiv) and catalytic copper(II) 3,5-diisopropylsalicylate (0.02 equiv) to allow the redox radical cyclization of polyene in 42% yield. A Tsuji

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• AlMe3 to 4,4-dimethyl-2,5-cyclohexadienone in the presence of a copper salt/chiral ligand and silylating reagent [37][38]. The racemic conjugate addition of nucleophiles to 5 was first investigated, starting with the Gilman reagent which was used in Takemoto and Iwata study (Scheme 6). In addition, a

• screening of various organocopper reagents (prepared from MeLi, EtMgBr, ZnEt2 or AlMe3 and copper halide or thiophene-2-carboxylate (CuTC)) was conducted, to no avail. In most cases, the starting material was recovered without indication that the pyrone ring interacted instead with the reagent. To decrease

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• -butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine on polystyrene) which is valuable for reaction scale-ups [75] is used. Alternatively, a CuAAc (copper-catalyzed azide–alkyne cycloaddition) reaction has been demonstrated where the copper catalyst is supported on an Amberlist A-21 resin

• continuous flow synthesis focus on palladium [85], cobalt [86], or copper (particularly useful for the widely used CuAAc) [87]. Nevertheless, the use of metal scavengers in large scale applications is limited as often discussed [88]. The use of a homogeneous scavenger as part of batch-based offline

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• reductively closed using SmI2. The synthesis of fragment 25 began with commercially available cyclohexenone (21), which underwent a copper-catalyzed vicinal difunctionalization with vinylmagnesium bromide and DMPU and trapping using methyl cyanoformate, leading to the formation of ketoester 22 (Scheme 4

• and 23 steps) to access grayananes with a cyclopentenone moiety on the A ring. It should be noted that although this is a racemic synthesis, intermediate 37 was also synthesized in enantioenriched form using a chiral copper catalyst for the cyclopropanation and a chiral auxiliary on the ester moiety

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• chiral copper complex. An extraordinary example of an asymmetric difluorination of alkenes with the migration of aryl or methyl groups was shown using a chiral aryl iodide catalyst [149][150] (Scheme 35). Depending on the nature of the migrating group, two mechanisms are possible that determine the

A novel bis-triazole scaffold accessed via two tandem [3 + 2] cycloaddition events including an uncatalyzed, room temperature azide–alkyne click reaction

• Ksenia Malkova,
• Andrey Bubyrev,
• Vasilisa Krivovicheva,
• Dmitry Dar’in,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1636–1641, doi:10.3762/bjoc.18.175

• in Scheme 1 speaks for the unusual facility with which the intramolecular azide–alkyne click reaction took place. Normally, intermolecular click reactions are copper-catalyzed [17][18][19][20]. Intramolecular positioning of the click reaction partners may eliminate the need for the metal-based

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

• reports found in the literature suffer from the requirement of hazardous intermediates and harsh reaction conditions. Here, we report a new six-step synthesis for c1G base, starting from 6-iodo-1-deazapurine. The key transformations are copper catalyzed C–O-bond formation followed by site-specific

• intermediates. Here, we present a new tactic for the syntheses of 1-deazaguanine and 1-deazahypoxanthine stimulated by a recently published route of our research group for the corresponding nucleosides [16][17], employing the same key reaction, namely the copper-catalyzed coupling of an aryl iodide with benzyl

• 3,4-dihydropyran in dimethylformamide to obtain the corresponding tetrahydropyranyl-protected amine 17. Subsequently, a copper-catalyzed C–O bond formation at C6 using benzyl alcohol in the presence of caesium carbonate, copper(I) iodide, and 1,10-phenanthroline furnished benzyl ether 18 in excellent

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• propargyl-containing compounds, including other CDs, to form a dimer [12]. Usually, such reactions proceed with a Cu(I) catalyst [27]; however, Cu(I) can be generated in situ by the reduction of Cu(II) [12][28] or by the dissolution of metal copper [29]. Moreover, the load of the catalyst varies from

• most crucial restriction in coupling two CD units by propargyl ether is the volatility of the latter compound. Thus, we discovered that performing the reaction at room temperature, prolonging the reaction time, and using an equivalent amount of the copper catalyst resulted in the best yields. Another

• slower and gives a lower conversion. Mourer and co-authors [12] also have reported varying reactivity of 6-azido permethylated CD over 6-azido CD in click reactions, claiming the presence of hydroxy groups on the secondary face reduces the catalytical activity of copper. Compound 11, prepared by standard