Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

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

• limited to electron-poor arenes like diazonium/iodonium salts or aryl iodides with electron-withdrawing substituents as aryl radical precursors, due to the limited accessible reducing power of photocatalysts that relied on a monophotonic excitation event. However, the vast majority of inexpensive

• reductants as a theme of ongoing debate [39]. Nonetheless, this protocol enabled the reduction of various electron-poor aryl iodides and aryl bromides and, for the first time, the reduction of aryl chlorides (albeit electron-poor ones) via visible light PRC in good to excellent yields (35–98%) (Figure 4A

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

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

• current as terminal oxidants were developed [139][140][141][142][143][144][145]. The key step in the catalytic cycle involving aryl iodides is the formation of iodine(III) species. Enantioselective oxidative processes mediated by chiral hypervalent iodine compounds were reviewed recently [146]. In the

• following example of styrene diamination by a chiral aryl iodide, the higher efficiency of the proposed catalyst compared to simpler aryl iodides was attributed to the additional stabilization of the I(III) intermediate by chelation via n–σ* interactions and hydrogen bonding [147] (Scheme 33). The

• configuration of the final product. A fundamentally different mechanism distinguishes the 1,2-diiodo-4,5-dimethoxybenzene catalyst from other aryl iodides. In contrast to the standard mechanism, in which iodine(III) is an active intermediate species, in the case of 1,2-diiodo-4,5-dimethoxybenzene, the iodine

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

• Mio Matsumura,
• Kaho Tsukada,
• Kiwa Sugimoto,
• Yuki Murata and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

• for the synthesis of unsymmetrical selenides with imidazopyridinyl groups substituted at position 3. Guo and Li et al. reported the reaction of Se powder with imidazopyridine and aryl iodides in the presence of KOH (2 equiv) as base using Cu(OAc)2 catalyst to form aryl imidazopyridinyl selenides [15

• powder with imidazopyridine and aryl iodides or alkyl halides in the presence of Na2CO3 (2 equiv) using the NiBr2/2,2-bipyridine system to give aryl or alkyl imidazopyridinyl selenides [24]. In these reactions, aryl iodides, arylboronic acids, and alkyl halides are coupled with Se powder to form diaryl

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• substrates (1n–p), and the desired borylation products (3n–p) were obtained in good yields. We also investigated the solid-state borylation reactions of aryl iodides and chlorides (Scheme 4). The reaction of 4-iodo-N,N-diphenylaniline (1q) under the optimized conditions at 130 °C for 30 min proceeded

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

• steric effects. Anilkumar and co-workers reported an iron-catalyzed Sonogashira coupling of aryl iodides with terminal alkynes in the presence of a catalytic system made up of the greenest solvent, water, in the presence of 10 mol % FeCl3·6H2O and 20 mol % 1,10-phenanthroline as ligand under aerobic

• conditions [13]. This system is applicable to sterically hindered aryl iodides or substituted aryl iodides with terminal arylalkynes (Scheme 2). K3PO4 was the effective base for the reaction of 4-iodoacetophenone with phenylacetylene. Ligands such as DABCO and trans-1,2-diaminocyclohexane were also tested

• the bench stability of the nanoparticles, and hence methylmagnesium bromide was introduced to retain the catalytic activity. Heterogeneous green protocols Rizi and co-workers reported a silica-supported green heterogeneous Fe(III) catalyst for the cross-coupling reaction of aryl iodides and

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

• with aryl iodides to generate intermediate D, which then undergoes reductive elimination to generate the desired products (Scheme 23). In 2017, Evano’s group [55] established a photoinduced, copper-catalyzed C–C cross-coupling of aryl halides, and heteroarenes. The cyclization of N-allyl-o-iodoanilines

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

• iridium(III) photocatalyst 2-I. Subsequently, Ahneman and Doyle reported a related process for the synthesis of a variety of benzylic amines 7 by the arylation of α-amino C(sp3)‒H bonds with aryl iodides 2 involving photoredox nickel catalysis (Scheme 4) [55]. In this protocol, bis(oxazoline) (BiOx) was

• photocatalyst. [PC] = photocatalyst, A = acceptor, D = donor. Proposed catalytic cycle for the photoredox-mediated HAT and nickel catalysis enabled C(sp3)‒H arylation. Proposed mechanism for photoredox nickel-catalyzed α-amino C‒H arylation with aryl iodides. Proposed catalytic cycle for the C(sp3)−H arylation

• benzylic C(sp3)‒H bonds with aryl bromides. Photoredox arylation of α-amino C(sp3)‒H bonds with aryl iodides. Nickel-catalyzed α-oxy C(sp3)−H arylation of cyclic and acyclic ethers. Photochemical nickel-catalyzed C–H arylation of ethers. Nickel-catalyzed α-amino C(sp3)‒H arylation with aryl tosylates

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

• -workers reported a one-pot synthesis of substituted anthracenes 37 from o-tolualdehyde 34 and aryl iodides 35 via a palladium-catalyzed C–H arylation with a silver oxidant (Scheme 8) [42]. During optimization studies, the authors noted that steric and electronic effects strongly affected the cyclization

• ] cyclotrimerization reactions with bis(trimethylsilyl)acetylene (23). [2 + 2 + 2] Alkyne-cyclotrimerization reactions catalyzed by a CoCl2·6H2O/Zn reagent. Pd(II)-catalyzed sp3 C–H alkenylation of diphenyl carboxylic acids with acrylates. Pd(II)-catalyzed sp3 C–H arylation with o-tolualdehydes and aryl iodides

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

• aryl iodides containing electron-donating and electron-withdrawing groups exhibited good to excellent results in the reaction. Notably, the yield of the Click reaction with 2-iodotoluene decreased due to the steric effects. Moreover, the utilization of an efficient heterogeneous catalyst and

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• ], aryl sulfonates [36], and in aryl trifluoroethyl sulfate [37], Scheme 1a) followed by the reaction of the thus formed aryl cation with an aromatic substrate. In an alternative approach, aryl radicals may be generated under photoredox catalysis conditions (mostly from arene diazonium salts or aryl

• iodides) [30][31] or by the direct photolysis of arylazo sulfones [38][39][40] and employed for the desired arylations. These reactions have the advantage of being applied to non-functionalized arenes but have the drawback to require a large excess of the nucleophilic reagent (the arene Ar–H) in up to 10

Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• the reaction towards various substrates under the optimized conditions (Figure 2). Electron-deficient aryl iodides were well tolerated furnishing the corresponding trifluoromethylation products in high yields. Among the tested nitrophenyl derivatives, p- and o-nitrophenyliodide gave the products in

• -donating ligand was more effective than an electron-deficient one (Table 2), and the reaction with benzimidazoline proceeded rapidly (Figure 4), the oxidative addition was suggested to be the rate-determining step. Conclusion In conclusion, we have developed a catalytic trifluoromethylation of aryl iodides

• , hexafluorobenzene was added as an internal standard and the mixture analyzed by 19F NMR spectroscopy for the calculation of the NMR yield. Then, the crude products were purified by preparative TLC to give pure products 3. Trifluoromethylation of aryl halides. Scope of aryl iodides. Yields determined by 19F NMR

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• ], (c) carbon–sulfur bond-forming reactions [9], (d) directed ortho-metalation and nucleophilic acyl substitution strategies [10], (e) Pd-catalyzed aminocarbonylation of aryl iodides, Suzuki–Miyaura and Sonogashira cross-coupling reactions [11][12][13], (f) Cu-catalyzed C–N coupling reactions [14], and

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• the nature of the halide: as a trend, aryl iodides are easier to reduce than aryl bromides and aryl chlorides [67][77]. Under organophotocatalytic conditions, the reduction can be achieved following two main strategies for accessing stronger reduction potentials: (a) tuning the electronics of the

• organic dye or b) tuning the stability of the reduced photocatalyst, allowing a second photoexcitation. For an example of the first strategy, Zhang and co-workers designed a new photocatalyst: Py-BTz-Py (OD19, Scheme 12), which was reducing enough (E(PC•+/PC*) ≈ −2.0 V) to activate the aryl iodides 12.1

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• reactivity of the complex was then studied in stoichiometric reactions with aryl iodides and iodonium salts. The difluoromethylation reaction was smoothly carried out at 90 °C with electron-rich and electron-poor aryl iodides. However, the reaction was more efficient with electron-poor aryl iodides (Scheme 1

• excess of TMSCF2H, might act as a reservoir of the unstable and reactive CuCF2H species. Xu and Qing reported a similar strategy for the difluoromethylation of electron-poor (hetero)aryl iodides at room temperature, using only 2.4 equivalents of TMSCF2H [40]. Note that the use of a strong base (t-BuOK

• functional group tolerance and was efficiently applied to the synthesis of CF2PO(OEt)2-containing (hetero)arenes, alkenes and alkynes (Scheme 7, reactions b–d) [50]. Later on, the same group depicted the Pd-catalyzed introduction of the CF2PO(OEt)2 residue on (hetero)aryl iodides [51] by using an in situ

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• of China, Beijing 100872, China 10.3762/bjoc.16.61 Abstract The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine

• ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the

• industrial waste and other side products. Particularly, the reductive carbonylation of aryl iodides to produce arylaldehydes with CO and H2 was seldom reported. Some homogeneous and heterogeneous catalytic systems based on palladium species using CO and H2 to complete the reductive carbonylation of aryl

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• , trimethylsilylacetylene (TMSA) was selected for coupling with aryl iodides in the presence of a catalytic amount of Pd–Cu/C and PPh3 using Et2NH as a base in methanol at 120 °C under microwave irradiation for 20 min. In the next step, the azide derivative was added to the reaction mixture. Finally, the reaction mixture

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• corresponding aryl iodide. The aryl radical can then add to the allylating reagent, which, after tosyl radical elimination, provides the desired product. Finally, the active catalyst is regenerated thanks to the use of DIPEA as a sacrificial reductant. Note that this reaction was inefficient with aryl iodides

• and alkyl iodides and bromides catalyzed by a heteroleptic copper complex, [Cu(I)(bcp)(DPEPhos)]PF6, under blue light irradiation (Scheme 20) [36]. The reduction of aryl iodides proceeded well, regardless of the electron density of the aromatic ring, and the products were isolated in good to excellent

• aryl iodides and bromides into the corresponding aryl radical to use the latter in further transformations (Scheme 21). First, a 5-exo-trig cyclization was carried out to access indolines, dihydrobenzofurans, indanes, cyclopentane, and pyrrolidines. The cyclized products were isolated in good to

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• -promoted and copper-catalyzed processes for the introduction of SeCF3 groups Copper(I) trifluoromethylselenolate complexes Copper(I) trifluoromethylselenolate was first prepared in 1985 by the group of Yagupolskii [12]. Then, CuSeCF3·DMF was tested in the trifluoromethylselenolation of (hetero)aryl iodides

• and showed promising results. However, the reactions were performed mainly with activated aryl iodides, and a high temperature was required to achieve acceptable yields. Three decades later, the group of Weng reported the synthesis of discrete SeCF3-containing copper/bipyridine (bpy) complexes [13

• tandem formation of C–Se and Se–fluoroalkyl bonds have emerged in the last five years. In 2014, Hor and Weng reported the trifluoromethylselenolation of (hetero)aryl iodides and alkyl bromides with the Ruppert–Prakash reagent, TMSCF3, elemental selenium, potassium fluoride, and silver carbonate under

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• -ethoxyvalerate as a partially bio-based solvent can be utilized as alternative reaction medium for copper- and auxiliary base-free Pd-catalyzed Sonogashira coupling reactions of aryl iodides and functionalized acetylenes under mild conditions. Twenty-two cross-coupling products were isolated with good to

• alkoxyvalerate anion with HI that formed during the reaction could be assumed. Conclusion In conclusion, we have demonstrated that a γ-valerolactone-based ionic liquid, tetrabutylphosphonium 4-ethoxyvalerate can be utilized as an alternative solvent for Pd-catalyzed Sonogashira coupling reactions of aryl iodides

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• )2 and P(2-furyl)3 with aryl iodides 19a and 19b led to the expected biaryls 20a and 20b in moderate yields (Scheme 3). All these reactions proceeded without byproducts being observed. In all cases unreacted substrate 9d was recovered in correspondent quantity. With the 5-(hetero)aryl-substituted 4

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165