Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• carbohydrates [44][45]. The C–C bond lengths within the pyran rings of halogenated analogues are between 1.50 and 1.54 Å, which is similar to native talose (18, 1.52–1.53 Å) (Table 1, entries 1–4). However, all specified bond lengths within the pyran rings are shorter for halogenated analogues compared to α-ᴅ

• to the non-halogenated compound. The puckering amplitude for an ideal cyclohexane chair, with C–C bond lengths of 1.54 Å, is 0.63 Å [50]. The azimuthal angle (θ) represents the distortion of the ring. For pyranose rings, an azimuthal angle of θ = 0° represents a perfect 4C1 chair, and an angle of θ

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• iminoiodinane reacts directly with the olefin to generate a short-lived alkyl-bound iodinane 7 or iodonium species 8 (Scheme 4f). Ligand coupling from 7 or extrusion of iodobenzene from 8 would furnish a carbocation intermediate 9 which could undergo C–C bond rotation prior to ring closure to form the aziridine

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• unit allows for spin localization at the 10-position of anthracene through C–C bond rotation, resulting in a tail-to-tail σ-dimer (Figure 1b). The σ-dimer exhibits an equilibrium state between the monomer radical and the σ-dimer in solution, and mechano-stimulus-induced C–C bond fission in the solid

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• mainly via metal-catalyzed C–N or C–C bond formation. Despite recent advances in the area of remote C–H functionalization, this strategy still requires some pre-functionalization of the starting material or the use of directing groups [28][29][30][31][32]. An alternative strategy is based on aromatic

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• -difluoroethylene and the disappearance of vinyl protons resonances in the 1H NMR spectra [78]. Addition to the C=C bond Halogen addition: 1,2-Difluoroethylene was reported to react with chlorine [46][79] and bromine [51] under irradiation, yielding 1,2-difluoro-1,2-dihaloethanes in moderate to high yield (Scheme 9

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

• predominately considered to be stable to isolation conditions, secondary and tertiary suffer from the elimination of HF, especially in the presence of silica gel or glass vessels. Therefore, benzyl fluorides have been derivatised, for example in C–O, C–N and C–C bond-forming reactions [18][19][20], thereby also

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

• [28] introduced the photoredox-catalyzed hydroacylation of styrene derivatives via deoxygenation of challenging aliphatic carboxylic acids (Scheme 1). The deoxygenation was promoted by phosphine reagents to form acyl radicals. The acyl radicals reacted with the C=C bond and formed the expected product

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

• halides, which involved a rhodium-bis(benzyl) complex (Scheme 2) [21]. Following these outcomes, as part of a research program aimed at a wide range of Rh-catalyzed C–C bond-formation reactions, in this paper, we report a Rh-catalyzed Ullmann-type homo-coupling reaction of aryl Grignard reagents. Results

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

• that a reductive radical-polar crossover pathway is likely to be involved in this transformation. Keywords: aryl halides; C–C bond formation; electroreduction; radicals; visible light; Introduction Alkene hydroarylation is an attractive method for the construction of alkylarenes, which serve as

• . Recently, the groups of Lin and Lambert [48] and Wickens [49] independently demonstrated that aryl chlorides with highly negative reduction potentials engaged in C–X (X = P, Sn, B) and C–C bond formation reactions involving aryl radical species by integrating photochemistry and electrochemistry [50][51][52

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

• position (ortho or para) available for electrophilic substitution [36]. They found that solvent played a significant role in directing the outcome of the reaction. In protic solvents, biphenols were selectively formed through C–C bond formation, whereas in pyridine, the generation of diaryl selenide

• P21/c [49]. It adopts a transoid geometry around the oxamide C–C bond with nearly 180° torsion angle. This provides the molecule with a planar geometry. It shows intermolecular hydrogen bonding between the amide O and NH moieties. (Figure S35, Supporting Information File 1). Oxamide 9 crystallized in

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• distinctive subset of compounds, including jadomycin, gilvocarcin, kinamycin, fluostatin, and lomaiviticin, arises from typical angucycline intermediates via oxidative C–C bond cleavage and subsequent ring rearrangement reactions. These atypical angucyclines exhibit intriguing chemical structures and various

• , Supporting Information File 1) [21][22]. In this study, we reveal the previously undisclosed facet that AlpJ-family oxygenases can function as cofactor-independent oxygenases when the hydroquinone intermediate CR1 (8) serves as the substrate. In this context, the enzymes autonomously catalyze oxidative C–C

• bond cleavage, ring opening, and rearrangement reactions, yielding the respective products. Furthermore, the reactions of 8 catalyzed by JadG and AlpJ could be quenched by superoxide dismutase (SOD), supporting a catalytic mechanism involving the generation of a substrate radical and the superoxide

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

• ions of 3. Finally, the structure of 3 was established by single-crystal X-ray structure analysis. The ORTEP diagram of 3 is presented in Figure 5 with the selected bond lengths and angles collected in Table 1. The cage C–C bond lengths of the addition sites are C1–C9: 1.623(2) Å and C21–C40: 1.6282(19

• ) Å, which fall within the range of the corresponding values reported for the crystal structures of methano-derivatives of C60 [5][21][22][23][24][25][26][27][28][29][30][31][32][33]. It is noteworthy that these C–C bond lengths are longer than those of the reported siliranes [34][35][36][37][38][39

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

• alcohols and afforded a good to excellent yield. Unfortunately, aliphatic amines such as isopropylamine and cyclohexylamine showed poor activity. C–C Bond formation via borrowing hydrogen Building C–C bonds by selective, efficient, and environmentally benign processes has been challenging and the most

• , which leads to the formation of a considerable amount of waste [52][53][54]. The BH approach allows a sustainable way for building C–C bonds by coupling abundant and cheap alcohols with ketones, nitriles, esters, and amides [4]. C–C Bond formation via alkylation of ketones with alcohols Several

• of t-BuOK (1.5 equiv) at 125 °C for 18 h (Scheme 28B). The proposed mechanism suggested the formation of α,β-unsaturated ketones as the intermediates, similar to the previous report [58] and the selective hydrogenation of the C=C bond was the last step. In 2018, Banerjee’s group developed the

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

• –C bond formation has received great interest due to the broad applications of functionalized indole derivatives. In this context, many groups developed different routes to 3-substituted indoles. In this mini-review, we just show the carbonylative approaches. Xing and co-workers presented a

• process was catalyzed by visible light in the presence of Mo(CO)6 (1 equiv) as CO source, I2 (2 equiv), and K2CO3 (3 equiv) at 120 °C in an inert reaction environment (N2) and in DMSO as solvent (Scheme 38). Functionalization through direct C–H carbonylations The direct functionalization of indoles via C

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

• depyrophosphorylation, whereas class II TSs utilize a general acid (a key Asp residue) to protonate the terminal C=C bond or epoxide group to yield a tertiary carbocation. The highly reactive carbocation is then converted to different carbocation intermediates, facilitated by the hydrophobic pocket of the TSs, which

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• motif in bioactive compounds and the synthetic utility of its olefinic C=C bond. The most extensively explored approach to this transformation is the transition metal-catalyzed C–N coupling between azoles and vinylating agents, including vinyl halides [4], boronates [5], sulfonium salts [6][7][8], and

• , producing the vicinal N-heterocycle-substituted olefin 9 as a mixture of stereoisomers in 65% yield. Finally, 4aa proved to be a viable nucleophilic VBX for the carboiodanation of 3-methoxybenzyne [35], furnishing the new ortho-alkenylated arylbenziodoxole 10 with exclusive C–C bond formation at the distal

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• substituted ortho-benzene. Stephenson and co-workers accessed 1,2-BCHeps 79a–c by insertion of alkenes into BCPs 78, and proposed the 1,2-BCHeps as isosteres of ortho-benzenes (Scheme 7A) [46]. The reaction proceeded via homolytic cleavage of a C–C bond adjacent to the imine functionality and stepwise alkene

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

• techniques employing transition-metal and photocatalysis [15][16]. These methods facilitate C–C bond formation, enabling the introduction of alkyl groups at the C2 position of quinazoline derivatives. While arylsulfanyl group rearrangement reactions have been documented by us for modifying 2,4-substituted

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

• likely due to the steric effect caused by the methyl group directly connected to the alkenyl C=C bond in reactant 1. After optimizing the reaction conditions, compounds 5a and 5b were isolated in 71% and 53% yields, respectively. Importantly, the generation of multiadducts in the thermal [2 + 2

Recent developments in the engineered biosynthesis of fungal meroterpenoids

• Zhiyang Quan and
• Takayoshi Awakawa

Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50

• molecular species withdraws a hydrogen atom, and the generated radical induces various reactions such as hydroxylation, unsaturation, epoxidation, halogenation, endoperoxidation, and C–C bond reconstruction, leading to the formation of diverse chemical structures [22][26][27][28][29][30][31]. Structure

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

• Yasuhiro Oishi,
• Motoharu Kitatani and
• Koichi Kusakabe

Beilstein J. Org. Chem. 2024, 20, 570–577, doi:10.3762/bjoc.20.49

• activation barrier. This steric hindrance effect is analogous to the well-known steric hindrance effect of the rotation around the C–C bond in ethane. Indeed, on the graphene surface, the possible conformations resulting from the rotation are effectively limited to conformation 2, due, in part, to the

• rotation at the alkyl chain (conformation II), as shown in Figure 1d. Rotational motion at the alkyl chain inevitably involves steric hindrance effects around the C–C bond. In particular, for motions corresponding to rotations around the C–C bond in PASE represented by the solid red line in Figure 1a and b

• how an activation barrier appears on the potential energy surface in PASE adsorbed on graphene. The conformational change between two bi-stable PASE structures can be regarded as rotational motion around a C–C bond in the alkyl chain. An origin of an activation barrier is the steric hindrance coming

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• from each of the bromo-substituted alcohols used by us have two main pathways of transformation under the action of base: 1) exo-tet cyclization with substitution of the bromine atom and formation of the spirocycle, and 2) migration of the exocyclic double C=C bond into the imide cycle (the process is

• )ethanol. In the latter case, the predominant process was found to be the base-promoted migration of the C=C bond of the arylidene fragment into the cycle. Examples of biologically active compounds and natural products based on THF/THP spiro-conjugates with pyrrolidine rings. DAS spirocyclizations reported

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• a terminal phenanthroline receptor substituent was synthesized. Upon irradiation in acetonitrile or DMSO with light of 436 nm, they underwent Z–E isomerization of the C=C bond, followed by very fast N→O migration of the acyl group and the formation of nonemissive O-acylated isomers. These isomers

• vibrations of the thiophene and amide carbonyl groups were observed at 1663–1678 and 1705–1713 cm−1, respectively. The 1H NMR spectra contained signals of methine protons (=CH–) in the region 7.92–9.02 ppm, which corresponded to the Z-configuration of the C=C bond. According to data previously obtained [14

• photoisomerization of the C=C bond, followed by very fast thermal N→O migration of the acyl group and the formation of O-acylated isomers. This rearrangement was accompanied by a decrease of the initial fluorescence intensity at 465–468 nm up to zero, since the resulting OAc− form was nonemissive. The reverse

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• their solvation sphere occupy part of the cavity and prevent non-coordinating guests from entering the binding cavity. By extending the spacer between the terpy and the arms from a single C–C bond to an amide functional group that also participates in the coordination of the Zn2+, non-coordinating