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

• previous results [21][22]. Consequently, we propose the reaction mechanism as shown in Figure 2. In the initial step, the Rh catalyst reacts with the Grignard reagent 4 to give the Rh(I)–aryl complex 7. Oxidative addition of 1,2-dibromoethane onto complex 7 then generates Rh(III)–aryl complex 8 along with

• . Conditions: a) The reaction was carried out at rt for 1–3 h without Mg. b) The side product 6h by SNAr reaction onto 3h was obtained in 8%. Tentative reaction mechanism. Ullmann and Ullmann-type homo-coupling reactions. Rh-catalyzed homo-coupling reactions. Rh-catalyzed homo-coupling reaction by using

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• hydrazone 3a. Synthesis of hydrazone 3b using phenylhydrazine hydrochloride. Synthesis of target 1,2,3-triazoles 4. Reaction conditions: 1 (0.5 mmol), arylhydrazine hydrochloride (0.55 mmol), EtOH (5 ml), then K2CO3 (1.5 mmol, 0.21 g), EtOH (5 ml). Proposed reaction mechanism. Reaction of 1d with hydrazine

• hydrate a. Synthesis of products 6. Reaction conditions: 1 (0.5 mmol), hydrazine hydrate (1.5 mmol, 0.08 g), EtOH (5 ml). Proposed reaction mechanism for the formation of products 6. Synthesis of methylated product 7. Optimization of the reaction conditionsa. Supporting Information Supporting Information

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• , providing the corresponding product 3aa in 74% yield. Several control experiments were conducted to gain insight into the reaction mechanism of the electroreductive process. The hydroarylation of cyclopropane-substituted styrene 2l resulted in the formation of ring-opening product 3al’, and the simple

Sustainable tandem acylation/Diels–Alder reaction toward versatile tricyclic epoxyisoindole-7-carboxylic acids in renewable green solvents

• Ayhan Yıldırım

Beilstein J. Org. Chem. 2024, 20, 1308–1319, doi:10.3762/bjoc.20.114

• 2.160 Å. These bond lengths support path I, which is a more valid pathway in the reaction mechanism. As can be seen in Figure 4, the energies of both the exo transition state and the exo product are lower than those of the endo, which also supports the experimental results. Conclusion Vegetable oils

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• , yielding clear-cut evidence for the proposed reaction mechanism [47][48][49][50][51][52][53][54][55][56][57]. We found that quenching of the singlet-excited Aza-H by 4-cyanopyridine is the main pathway for the 3-CR, while the triplet state of our catalyst, which is formed with a quantum yield as high as

• contrast to all previous measurements, no signal of the Aza-H radical cation generated through two-photon absorption is detected. This can be easily rationalized as the radical cation is most likely rapidly quenched by TsNa (compare the proposed reaction mechanism regenerating the oxidized catalyst). That

• underlying reaction mechanism. On the other hand, the relatively high triplet formation quantum yield of Aza-H along with its triplet energy on the order of 2.3 eV permit efficient and metal-free reactions via energy transfer catalysis, as shown for the photosensitized isomerization of stilbene and cinnamyl

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

• rise to either diaryl selenoxide via dehydration or diaryl monoselenide via reductive elimination by eliminating H2O2 [39]. Observation of m/z peaks for compound 8 clearly confirmed the formation of diaryl selenoxide in the reaction. Mechanism for the formation of oxamides The possible reaction

• anthranilate with SeO2. Reaction mechanism for the formation of diaryl monoselenides. Reaction mechanism for the formation of oxamides. Reaction mechanism for the formation of quinone 10. Resonance structures for the delocalization of the nitrogen lone pair into the π-system. Summary of NBO analysis. Single

• mechanism for the formation of oxamide is shown in Scheme 6. Formation of acetanilide in the reaction of aniline and acetonitrile is known to occur in the presence of Lewis acid catalyst Al2O3 [55]. In our case, either SeO2 (Lewis acid) or H2SeO3 (Brønsted acid) may act as acid catalyst to convert aniline

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• . The regioselectivity in the addition reaction of 1 with C70 was explained earlier in terms of the interaction between the HOMO of 1 and the LUMO of C70 [16]. The reaction mechanism of ethylene with a silylene substituted with thiolate ligands has been studied using theoretical calculations, in which

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• mesitylene (Scheme 13). The formation of manganese(III) alkoxide intermediate Mn7-a, was believed to be the first step in the reaction mechanism which then releases the aldehyde under formation of hydride complex, Mn7-b. Then, the alcohol reacts with the hydride complex under release of hydrogen gas and

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• , there exists a competition for the dissociation of the β or γ-bond that yields undesired thermal degradation products through pathway A or the parent diene via pathway B, respectively. This dissociation follows a highly asynchronous but concerted reaction mechanism and may involve bispericyclic post

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

• reaction mechanism proceeds with an initial reduction of Pd(II) to Pd(0) followed by oxidative addition on the ArCH2–Cl bond to form the ArCH2–PdII–Cl complex. Then, insertion of CO, from TFBen, takes place followed by nucleophilic displacement and reductive elimination. The obtained compound undergoes

• . Meanwhile, they also discovered that by conducting the reaction under non-oxidative conditions the reaction mechanism changed, leading to the formation of indol-2-acetic esters via the H–PdII–I species formed in situ [19]. The reaction was performed in the presence of PdI2 and KI (2 mol % and 20 mol

• the catalyst undergoes reduction, therefore, rather using only CO, a mixture of CO–air (12:48 bar) was used with the aim of oxidizing the Pd(0) species in order to restore the catalyst able to catalyze the process again. The reaction mechanism proceeds with an initial interaction between the Pd(II

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• 82 and 83 by TSs led to the production of ruptenes including compounds 84–90, which revealed the structure of the proposed intermediates for the cyclization reactions and therefore provided important insights into the reaction mechanism [49] (Figure 6c). With the aid of artificial prenyl analogs, a

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

• Lilian M. Maas,
• Alex Haswell,
• Rory Hughes and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2024, 20, 921–930, doi:10.3762/bjoc.20.82

• fluoride product (Table 1, entry 9). Although representing a considerable drop in efficiency compared to using 1.25 equiv of BT-SCF3, this observation provides an interesting insight into the reaction mechanism (vide infra). Changing the solvent from DCM to THF or MeCN resulted in no significant change in

• , replacing the benzylamine coupling partner with phenylalanine methyl ester provided dipeptide 5t in 67% yield (Scheme 3b). With the scope of the deoxyfluorination process established, our attention turned to an investigation of the reaction mechanism (Scheme 4). As demonstrated in our previous work

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• -positions to the ester group were all well-tolerated (Table 3). To gain further insights into the reaction mechanism, we conducted control experiments. Given the utility of diaryliodonium salts in radical chemistry, we introduced 2 equivalents of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) or 2 equivalents

• tested in the reaction under the standard conditions, however, product 3aa was not obtained. Based on the literature known results and the experimental evidences [35][36], we proposed a plausible reaction mechanism (Scheme 2b). The reaction started with the formation of radical intermediate A from

• protocol enables the efficient formation of two chemical bonds in one pot, representing a valuable tool for the synthesis of polycyclic benzocoumarins. Our ongoing research endeavours are dedicated to explore the detailed reaction mechanism with the ultimate aim of broadening the scope and applicability of

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• [32][33][34][35][36][37][59][60][61][62], upon the loss of dinitrogen. The radical I further adds to the terminal position of 1,3-butadiene (2a) to produce hybrid allylPd radical II, which would exist in equilibrium with π-allyl complex III. Following the classical Tsuji–Trost reaction mechanism, a

HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines

• Luan A. Martinho and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55

• report from the literature [24] a plausible reaction mechanism is shown in Scheme 6. It involves the nucleophilic attack of the aminopyridine 1 to the HPW-activated carbonyl compound 2, followed by iminium ion formation (iii) and [4 + 1] cycloaddition with the isocyanide. A 1,3-hydrogen shift yields the

• scale-up of the HPW-catalyzed GBB reaction (5.0 mmol) between 2-aminopyridine (1a), 4-nitrobenzaldehyde (2a) and cyclohexyl isocyanide (3) in EtOH under μw heating. Plausible reaction mechanism for the HPW-catalyzed GBB reaction. Optimization of the reaction conditions.a Comparison of reaction

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• , rendering this protocol applicable for the chemoselective conversion of aromatic aldehydes to corresponding bis(indolyl)methanes in the presence of aliphatic aldehydes and ketones [81]. The proposed reaction mechanism for this protocol is showcased in Scheme 5. At the beginning of the reaction, the bromide

• electron-withdrawing substituents. The reaction mechanism is based on the activation of the carbonyl group by molecular I2, through the formation of a halogen bond, which lowers the LUMO of the carbonyl moiety, increasing its electrophilicity, and thus allowing the addition of the indole group (Scheme 7

• excellent yields (85–98%) in a more facile manner. The reaction mechanism is similar to other halogen-bond donor catalysts (Scheme 14). While the broad substrate scope is a crucial benefit of this approach, the use of a toxic solvent and the slow reaction rates were some of the drawbacks that would need to

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

• Stern–Volmer constant (Ksv = 1146 M−1 with acid vs Ksv = 603 M−1 without acid). The reaction mechanism continues with the fragmentation of 33 into radical 34. From radical 34 the annulation reaction initiates via intermolecular radical addition, resulting in the formation of intermediate 35. After

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• 4aa [35] was isolated in 62% yield (Scheme 4). On the basis of the transformation of 3aa to 4aa, a tentative reaction mechanism is proposed. As shown in Scheme 5, the spiropyridazine-benzosultam 3aa was firstly oxidized to intermediate A. Next, an aziridine was formed with the hydrolysis of the amide

• regioselectivity. Comparision of previous work with this work. The effects of substituent groups on the [4 + 2] annulation reaction. Reaction conditions: 1 (1.0 mmol), 2 (1.5 mmol), Et3N (2.0 mmol), MeCN (10.0 mL), 25 °C, 2.0 h. Gram-scale synthesis of 3aa. The transformation of 3aa. The reaction mechanism of the

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• into the corresponding bis(fulleroid) product after 4 h of reaction (Figure S1 in Supporting Information File 1). Importantly, the observation of this intermediate represents an experimental proof of the proposed reaction mechanism. Confirmation that only one unit of 1a reacted with C70 in the reaction

•  1), unveiled the following reaction mechanism: initially, an oxidative coupling of the two alkyne moieties of our model 1a leads to the formation of INT 1, as previously reported [33]. This step, with a Gibbs energy barrier of 25.7 kcal·mol−1, is the rate-determining step for this process. Next, INT

Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

• Youlong Du,
• Haibo Mei,
• Ata Makarem,
• Ramin Javahershenas,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2024, 20, 212–219, doi:10.3762/bjoc.20.21

• . Control experiments. Proposed reaction mechanism. Scale-up synthesis. Optimization of reaction conditions.a Supporting Information Supporting Information File 8: Experimental details and spectral data. Funding We gratefully acknowledge the financial support from the National Natural Science Foundation

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• structure and the reaction mechanism are the keys to understanding chemical reactivity and selectivity [65][66][67]. In the area of carbohydrate chemistry, a lot of efforts are devoted to finding relationships between the fine details of molecular structures of both glycosylation partners (glycosyl donor

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• photooxygenation, Hock rearrangement and Friedel–Crafts reaction, which is supposed to proceed through aldehyde 3 (see further discussion below on the reaction mechanism). To complete this exploratory work, we envisaged to add an external aromatic nucleophile to the reaction mixture, namely 1,3,5-trimethoxybenzene

Copper-promoted C5-selective bromination of 8-aminoquinoline amides with alkyl bromides

• Changdong Shao,
• Chen Ma,
• Li Li,
• Jingyi Liu,
• Yanan Shen,
• Chen Chen,
• Qionglin Yang,
• Tianyi Xu,
• Zhengsong Hu,
• Yuhe Kan and
• Tingting Zhang

Beilstein J. Org. Chem. 2024, 20, 155–161, doi:10.3762/bjoc.20.14

• gram-scale preparation was carried out using 1a, that afforded the desired product in 96% yield (Scheme 4, reaction 4). To gain more insight into the reaction mechanism, several control experiments were carried out (Scheme 5). On one hand, the failure of substrates 10–15 to participate in the reaction

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• generalizing the elucidated reaction mechanism to other [2 + 2] CA–RE reactions involving TCNE and TCNQ as electrophiles might be difficult. They emphasized the significance of considering a pre-equilibrium state of the charge-transfer complexes between the alkynes and alkenes and mentioned that the

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• derivatives. UV–vis spectra of substrates; [1a] 0.33 M, [2a] 0.11 M. Selected works for the construction of dihydropyrido[1,2-a]indolones and current methodology. Substrate scope of the cascade reaction. Radical trapping experiment. Plausible reaction mechanism. Optimization of reaction conditions.a