Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• peracetic acid as a terminal oxidant [20]. Recently, Kočovský et al. disclosed a method employing 2-methylbenzamide and benzonitrile to yield 3-aryl-substituted isoquinolinone derivatives in the presence of n-butyllithium [21]. On the other hand, the intramolecular oxidative cyclization is also a viable

• ) diacetate (PIDA) [22][23]. And more recently, Du and our group have developed a method for the chemoselective cycloisomerization of o-alkenylbenzamides to 3-arylisoquinolinones, using PhIO as oxidant in combination with a catalytic amount of trimethylsilyl trifluoromethanesulfonate [24]. Although

Novel oxidative routes to N-arylpyridoindazolium salts

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

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• -pyridine substituted diarylamines, either using bis(trifluoroacetoxy)iodobenzene as an oxidant, or electrochemically, via potentiostatic oxidation. Electrochemical synthesis occurs under mild conditions; no chemical reagents are required except electric current. Both approaches can be considered as a late

• salts. The oxidative behavior of substituted diarylamines is known to be very diverse and strongly influenced by the substituents in the phenyl rings as well as by the type of the oxidant. Diarylamines can serve as precursors for a wide variety of practically useful compounds such as diarylnitroxides

• containing electron-donating and electron-withdrawing groups were taken as the starting compounds (Scheme 2). As an oxidant, bis(trifluoroacetoxy)iodobenzene (PIFA) was used. It allowed obtaining the targeted heterocyclic cations in practical 49–54% yield for all starting diarylamines. Notably, a minor

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• into pentacycles 67. The same products were obtained when CoBr2 was used as external oxidant in the one-pot cascade reaction (Scheme 24, conditions b). No substantial improvement in the yields of 67 and 69 was observed when the synthesis was carried out in two steps, performing the GBB reaction under

• inert atmosphere and oxidizing 64 in the presence of CoBr2 (Scheme 24, conditions c and d; one-pot: 10–43%, two steps: 11–37% yields). Interestingly, polycycles 69 were formed when I2 was employed as the oxidant (Scheme 24, conditions e), which was presumably due to the coordination between the oxidant

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• optimized conditions, revealing the tetrazole-substituted iodane 1a to be the best oxidant for this reaction (Table 2). The two suitable methods (A: HCl in EtOAc; B: TBACl in MeCN) were then applied to a variety of activated alcohols. The best option is shown in Figure 5. Model substrate 4a could be

• was investigated, potentially leading to the formation of a hydroxy(chloro)iodane intermediate. This intermediate either liberates hypochlorous acid as the terminal oxidant or undergoes a direct ligand exchange with the alcohol, followed by oxidative elimination to form the aldehyde. Thus, these

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• membranes to ensure a high proton conduction or leading to an efficient reaction production of hydrogen and oxygen gases, with no risk of electrolyte leakage and restricted gas-crossover [15][16][17]. Also, besides their conductivity and their low permeability to fuel and oxidant, the chemical and

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• iodine as a super-stoichiometric oxidant. The catalyst system has precedent for also facilitating oxygenation reactions [82], which was observed as a competing pathway under these conditions. The catalytic cycle proposed by the authors begins at resting state I (Figure 31), which is generated in situ and

• is subsequently oxidised to Mn(V)-oxo species II by hypervalent iodine oxidant PhIO. This can perform a HAT from the benzylic substrate, in turn generating a benzylic radical and Mn(IV)-hydroxy species III. Ligand exchange with the fluoride source affords complex IV, which performs FAT with the

Tetrabutylammonium iodide-catalyzed oxidative α-azidation of β-ketocarbonyl compounds using sodium azide

• Christopher Mairhofer,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1510–1517, doi:10.3762/bjoc.20.135

• ammonium iodides [40]. Interestingly, designer catalyst C1 was found being catalytically superior compared to Bu4NI (TBAI) when using H2O2 as the oxidant. Furthermore, it turned out that addition of PBN (phenyl N-tert-butylnitrone) has a beneficial effect on the reaction and that carefully buffered

• conditions are best-suited. We have recently established the use of dibenzoyl peroxide (DBPO) as a very powerful oxidant for oxidative heterofunctionalization reactions using simple nucleophilic inorganic salts as heteroatom transfer reagents [39][41]. This was successfully demonstrated for the non-catalyzed

• Bu4NI allowed for the clean and selective formation of 1a, we observed significant amounts of the α-I-ketoester 3 when using KI instead. Having established the combination of DBPO and Bu4NI as the best-suited catalyst/oxidant combination for the α-azidation of 1a using NaN3, we finally optimized

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

• Ziya Dağalan,
• Muhammed Hanifi Çelikoğlu,
• Saffet Çelik,
• Ramazan Koçak and
• Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

• alkenes. We previously developed a dihomohalogenation method using selectfluor as an oxidant [27]. Herein, we synthesized bicyclic oxy- and alkoxyfluorine compounds using selectflour as an electrophilic fluorination reagent, water and various alcohols as an nucleophile. Results and Discussion In this

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl₂ and NH₄SCN/KSeCN

• Jialiang Wu,
• Haofeng Shi,
• Xuemin Li,
• Jiaxin He,
• Chen Zhang,
• Fengxia Sun and
• Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

• oxidant. This metal-free approach was postulated to involve the in situ generation of reactive thio/selenocyanogen chloride (Cl–SCN/SeCN) from the reaction of PhICl2 and NH4SCN/KSeCN, followed by an electrophilic thio/selenocyanation of the pyrazole skeleton. Keywords: PhICl2; pyrazoles; selenocyanation

• oxidant (Scheme 1a–c) [49]. For example, Xu reported that a series of 4-thiocyanated 5-hydroxy-1H-pyrazoles was synthesized by a K2S2O8-promoted direct thiocyanation of pyrazolin-5-ones at room temperature, using NH4SCN as thiocyanogen source (Scheme 1a) [20]. Similarly, utilizing NH4SCN and K2S2O8

• NH4SCN (Table 1, entries 4–6). Next, other oxidants including phenyliodine(III) diacetate (PIDA), phenyliodine(III) bis(trifluoroacetate) (PIFA), iodosobenzene (PhIO), and NCS were applied, and the results indicated that PhICl2 was the most effective oxidant (Table 1, entries 7–10). Later on, when the

Hypervalent iodine-catalyzed amide and alkene coupling enabled by lithium salt activation

• Akanksha Chhikara,
• Fan Wu,
• Navdeep Kaur,
• Prabagar Baskaran,
• Alex M. Nguyen,
• Zhichang Yin,
• Anthony H. Pham and
• Wei Li

Beilstein J. Org. Chem. 2024, 20, 1405–1411, doi:10.3762/bjoc.20.122

• hypervalent iodine catalyst precursor, Selectfluor as the oxidant, and LiBF4 as the lithium salt for hypervalent iodine activation, we were gratified to observe the formation of the desired oxazoline 3 in 59% yield as the major regioisomer in nitromethane (MeNO2) solvent (Table 1, entry 1). To further improve

• entry 7 in Table 1, resulting in the formation of the desired oxazoline product 3 in 61% isolated yield. Control reactions in the absence of either the precatalyst or oxidant afforded no product formation (Table 1, entries 11 and 12). The control reaction in the absence of the lithium salt only afforded

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• breakdown of ethyl vinyl ether and trapping of ethanol, yielding radical 84. To regenerate the photocatalyst, PhSSPh functioned as an oxidant. After protonation upon the β-elimination step, PhS− contributed a hydrogen atom to both 83 and 84, alongside regeneration of the HAT catalyst. Lastly, the acetal

Rhodium-catalyzed homo-coupling reaction of aryl Grignard reagents and its application for the synthesis of an integrin inhibitor

• Kazuyuki Sato,
• Satoki Teranishi,
• Atsushi Sakaue,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai,
• Hiroyuki Takeda,
• Tatsuo Kinashi and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 1341–1347, doi:10.3762/bjoc.20.118

• yields, especially 1,2-dibromoethane was the best oxidant. The reaction proceeded in good yield, even if 0.5 equiv of 1,2-dibromoethane were used in this reaction, as shown in Table 1, entries 7 and 8. However, it has been confirmed that this reaction did not proceed when no alkyl halide was added to the

• yield. It is interesting that the reaction proceeded without adding the oxidant (1,2-dibromoethane) when 1,2-dichloroethane was used as the solvent, although a slight decrease in yield was observed (Table 2, entry 14). Based on these results, we selected RhCl(PPh3)3 as the Rh catalyst and THF as the

• Grignard reagents. Rh-catalyzed one-pot Ullmann-type reaction with bromobenzene under optimized reaction conditions. Synthesis of compound 10n as a candidate for an integrin inhibitor. Examination of various alkyl halides as an oxidant. Examination of various Rh catalysts and solvents. Supporting

Oxidative hydrolysis of aliphatic bromoalkenes: scope study and reactivity insights

• Amol P. Jadhav and
• Claude Y. Legault

Beilstein J. Org. Chem. 2024, 20, 1286–1291, doi:10.3762/bjoc.20.111

• ). We then explored catalytic conditions for the generation of the iodine(III) reagent. Remarkably, when catalytic PhI (0.2 equiv) was employed for in situ generation of Koser’s reagent by using m-CPBA (1.2 equiv) as an oxidant, almost similar results were obtained (Table 2, entry 1) with those obtained

• type haloalkenes. (b) Fate of unsymmetrical dialkyl ketones on direct bromination. (c) This work. Substrate scope. Unless otherwise stated 0.2 mmol of 1 was used and the isolated yields are given. Proposed catalytic cycle. Conditions screening (without oxidant)a. Conditions screening (with oxidant)a

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• selenious acid containing polyaniline via chemical oxidation of aniline with SeO2 as oxidant [45]. Further, Tanini et al. described that selenium dioxide has potential to oxidize aniline to form nitrobenzene in aqueous medium [46]. These findings irrevocably confirmed that aniline undergoes significant

• interactions are rarely reported and currently gaining interest [59]. Computational studies To comprehend the role of electron-donating and -withdrawing groups in arylamine oxidation using SeO2 as oxidant, DFT calculations were carried out on the arylamines and SeO2 using Gaussian 16 [60]. The molecular

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• positions (Equation 3). In the context of the radical process, it is noteworthy that a standard household LED lamp can serve as an efficient initiator, capable of triggering bromine photolysis (Equation 3, top) [45]. Hence, no oxidant-derived residues apart from water are formed and, at the end of the

• reaction time (4 h overall, entries 3 and 4 in Table 1). In these last experiments a whitish solid appeared during addition of the oxidant, initially observed in the one with lower water amount (Table 1, entry 3). The 1H NMR confirmation of the nature of the solid as 3a, makes clear that phase separation

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• ., in two different periods, reported two paradigmatic examples for indole syntheses. In 2010, they developed the synthesis of 1-(alkoxyarylmethyl)indole-3-carboxylic esters from 2-alkynylaniline imines by using PdI2/KI as catalyst system and oxygen as oxidant [15]. In particular, the reaction was

• indole derivatives were obtained by catalyzing the reaction with 5 mol % of Pd(tfa)2 (palladium(II) trifluoroacetate) and 1.5 equivalents of p-benzoquinone as oxidant in a 1:5 DMSO/MeOH solvent mixture at a temperature between 0 °C and 15 °C and, for a time between 48 and 120 hours depending on the

• ] as catalyst to achieve an NH-indole–C–H carbonylation [57]. A base was added to improve the efficiency of the process and an oxidant to restore the catalytic active species. The reaction was carried out under a low pressure of CO (1 bar) at 110 °C in xylene for 24 hours (Scheme 26). In 2018, the Zhou

Regioselective quinazoline C2 modifications through the azide–tetrazole tautomeric equilibrium

• Dāgs Dāvis Līpiņš,
• Andris Jeminejs,
• Una Ušacka,
• Anatoly Mishnev,
• Māris Turks and
• Irina Novosjolova

Beilstein J. Org. Chem. 2024, 20, 675–683, doi:10.3762/bjoc.20.61

• were oxidized to the corresponding sulfonylquinazolines 8. Inspired by our previous work [19] a TFAA/H2O2 oxidizing system was tried first but yielded several side-products, such as the hydrolysis product and unwanted oxidation of the quinazoline N3 position. Changing the oxidant to mCPBA (with 96

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• unreacted Li+@C60 serves as an oxidant for the reduced monoadducts potentially generated by SET from reactants to monoadducts. These factors contribute to the suppression of multiadduct formation, resulting in the selective generation of the target monoadducts. Specifically, Li+@C60, influenced by the

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

• atmosphere which is an environmentally benign oxidant. Further screening using dioxane as solvent resulted in an increase in the yield to 55%, whilst DMF gave access to 3a in a lower yield (30%) (entries 2 and 3, Table 4). Next, we considered testing the performance of copper iodide (CuI, 20 mol %) as

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

• and colleagues introduced an interesting metal- and oxidant-free photocatalytic C–H alkylation method for coumarins 18 [17]. The method utilized triphenylphosphine and sodium iodide, along with readily available alkyl N-hydroxyphthalimide esters (NHPIs) 3 as the alkylation reagents (Scheme 10

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

• oxidant to generate an oxygen-radical cationic intermediate, which undergoes abstraction of a hydrogen radical (or loses a proton first, followed by an electron) to afford an oxonium ion intermediate. Finally, the oxonium ion is attacked by various nucleophiles to obtain the target functionalized product

• benzylic ethers occurs at room temperature in the presence of Cu(OTf)2/InCl3 as catalysts and DDQ as oxidant (Scheme 3) [51]. By this route, a series of 2-alkoxymalonate diester derivatives was synthesized through direct CDC reaction. The mechanism study showed that the first step of the catalytic cycle

• oxidative alkylation of cyclic benzyl ethers with malonates or ketones. Oxygen is used as a terminal oxidant at atmospheric pressure. The key intermediate of this oxidative coupling reaction is benzyl alcohol intermediate C (Scheme 4) [52]. The generation of N–O radicals from NHPI in the presence of oxygen

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

• molecular iron catalyst II and stoichiometric hydroxyiodinane as a terminal oxidant [38]. It is proposed that an azidoiodinane is generated in situ and serves as the radical initiator, generating an azido radical which adds to the less substituted position on the alkene. The resultant transient radical is

• in linear internal alkenes. Building on this key iron catalysis result, our group and that of Shi contemporaneously reported the photochemical diazidation of alkenes using stoichiometric iron and no external oxidant or ancillary ligand, providing a simple protocol for the preparation of vicinal

• azides for a wide range of both activated (benzylic) and unactivated carboxylic acids. Control reactions support the intermediacy of alkyl radicals and the absence of carbocation rearrangements in a variety of probe substrates disfavor the reaction proceeding via RPC. Intriguingly, no additional oxidant

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

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• chromophores, which are coupled through a Buchwald–Hartwig coupling reaction (another NI-PTZ paper) [39]. The oxidation of the PTZ unit was readily performed by treatment with H2O2 as oxidant (Scheme 1). All compounds were obtained with satisfactory yields and the molecular structures were fully characterized

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

• ], antiviral [11][12], antibacterial [13][14][15], antimalarial [16][17], anti-inflammatory [18][19], anti-oxidant [20][21][22], antifungal [23][24] and antibiotic [25][26] and as enzyme inhibitors [27][28]. Several pharmaceuticals, polymers and naturally occurring compounds, including heme, chlorophyll