Synthetic applications of the Cannizzaro reaction

• Bhaskar Chatterjee,
• Dhananjoy Mondal and
• Smritilekha Bera

Beilstein J. Org. Chem. 2024, 20, 1376–1395, doi:10.3762/bjoc.20.120

• synthetic tool for the construction of functionalized molecules. Dating back to the 19th century, this reaction, though initially used for the synthesis of an alcohol and acid functionality from aldehydes, has henceforth proven useful to generate diverse molecular entities using both intermolecular and

• aldehyde molecules, forming an alcohol and an acid [1][2][3][4]. Since its discovery in 1853, the Cannizzaro reaction has emerged as an important reaction in synthetic organic chemistry with intermolecular, crossed, and intramolecular versions as demonstrated by numerous applications. Notably, the

• Cannizzaro reaction has come across with subtle developments and changes in base modifications leading to compounds of potential interest [5][6]. The intermolecular Cannizzaro reaction is a chemical process in which two molecules of a non-enolizable aldehyde (2R1CHO) are disproportionated by a base to

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

• organic dye Mes–Acr–MeClO4 as photocatalyst (Scheme 5). They demonstrated intermolecular radical cyclization of o-hydroxybenzoic acid derivatives with terminal alkynes to afford flavone derivatives. Here, functionally diverse flavonoids were synthesized in moderate to excellent yield by reacting various

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

• by preventing overreduction [39]. While the metal-catalyst-free radical cyclization of alkene-tethered aryl halides has been well documented in the literature [40][41][42][43], the efficient intermolecular hydroarylation of alkenes still relies on the use of transition-metal catalysts, including Pd

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• 1b and SWNTs in these samples. The difference in the intensity and Raman shift of the signals in the radial breathing mode (RBM) region would be another evidence for the strong intermolecular interaction between Cu-nanobrackets 1b and SWNTs. The interlocking of the SWNTs may restrict its radial

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• para-substituents were used and the reaction from FIDO to FIDS was found to tolerate both electron-donating and -withdrawing functional groups as shown in Table 2. It is well known that functional groups with larger steric hindrance can reduce intermolecular forces. Consequently, a tert-butyl

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

• 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

• a monoclinic crystal system in the space group P21/c. The structure was similar to the structure of oxamide 3 (Figure 2). The hydrogen of the NH unit was concealed by the oxygen atoms of the C=O and OMe units. Consequently, it did not engage in intermolecular hydrogen bonding. Due to the planar

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

• compound E. Cyclization occurred via dehydrogenation and intramolecular aldol condensation and in the last step hydrogen transfer provided the desired cyclic product H (Scheme 35). In 2020, Maji and Adhikari reported a phosphine-free N,N-amine–manganese complex-catalyzed stereoselective intermolecular and

Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines

• Vladislav V. Nikol’skiy,
• Mikhail E. Minyaev,
• Maxim A. Bastrakov and
• Alexey M. Starosotnikov

Beilstein J. Org. Chem. 2024, 20, 1069–1075, doi:10.3762/bjoc.20.94

• molecule is not shown), 13c (top right), and 13d (bottom) with thermal ellipsoids set at a 50% probability level. Intermolecular hydrogen bonds are drawn with dashed lines. Methods for the synthesis of isoxazolo[4,5-b]pyridines: (A) annulation of an isoxazole fragment to a pyridine ring; (B) annulation of

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• molecules; N-heteroacenes; hydrogen bonding; optoelectronic properties; organic field-effect transistors; organic semiconductors; Introduction The role of weak intermolecular interactions in tuning the properties of organic semiconductors has garnered significant attention in the past two decades, owing to

• constructed via intermolecular N–H∙∙∙N interactions. However, vacuum-deposited films afforded poor hole transport. In separate work, Bunz et al. reported the serendipitous and understated synthesis of an H-bonding capable 1,4-dihydropyrazino[2,3-b]quinoxaline-2,3-dione (Figure 1a) [23]. In 2018, Takeda et al

• respect to the carbonyl groups (Figure 6b) and 5.25° concerning peripheral rings 1 and 3 (Figure 6c). The unit cell is composed of a dimer of 2b held together by intermolecular N–H∙∙∙N and C–H∙∙∙O=C H-bonds with average distances of 2.30 Å and 2.28 Å, respectively (Figure 6d and 6e). The herringbone

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

• difunctionalization of alkynes with various heteroatom and carbon nucleophiles [27][28][29][30][31][32][33][34]. Specifically, intermolecular trans-iodo(III)functionalization of alkynes has been achieved using oxygen nucleophiles such as alcohols [28][32], ethers [33], carboxylic acids [31], phosphate esters [31

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• . Developing more efficient and diverse macrocyclization strategies is urgently needed to overcome issues such as insufficient regioselectivity, intermolecular oligomerization, the overuse of protective groups, and other drawbacks [8]. In the biosynthetic logic, these natural products are produced by the large

• the current issues, such as insufficient regioselectivity, intermolecular oligomerization, and the overuse of protective groups. The biosynthetic studies demonstrated that thioesterase (TE) domains exhibit a high level of chemoselectivity and regioselectivity in late-stage macrocyclizations. This

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• seen with imidazolidines (cf. for IPr TEP[Ir] = 2050.2 cm−1) [34]. A benchmarking exercise was then performed looking at the reactivity of 13 compared against reaction of symmetrical IPrAuCl across a range of known gold-mediated transformations of alkynes featuring intermolecular attack [35

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

• °, fold angle 4.38°). The molecular packing of compound 3b was characterized by the presence of numerous π–π interactions (Figure 4). Intermolecular interactions in the benzo[b]thiophene fragment (red planes in Figure 4) were characterized by the following parameters: plane centroid–plane centroid

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

• tweezers with tert-butyl groups positioned farther from the salphen via alkyne spacers were synthesized [42]. While, like in the parent tweezers 12, no intercalation of aromatic guests was observed in the closed form, strong intramolecular and intermolecular Pt–Pt bonds were achieved in the solid state

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• require geminal substitution or backbone heteroatoms, internal alkenes are often not tolerated, and intermolecular reactions require high temperatures which can lead to significant catalyst decomposition [20]. This is usually addressed by employing bulky or strong donor ligands [21][22]. Novel strategies

• )-catalyzed alkene hydroamination were intermolecular additions by He [15][16] and intramolecular additions by Widenhoefer [12][13] in 2006, each catalyzed by phosphine ligand supported gold triflate (Ph3PAuOTf). Shortly after, arguments were made that reaction profiles were indistinguishable from those

• tropos BIPHEP-gold(I)-catalyzed hydroamination of alkenylureas in 2012 [9]. Michon [5][6][7][8][10] and Widenhoefer continued to make advancements in asymmetric intra- and intermolecular variants, and unique solvent and anion dependencies continue to be examined from a theoretical standpoint. For example

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• intermolecular interactions with an aryl ring in an adjacent molecule. The two aryl rings within the molecule are near-perpendicular to each other and this conformation leads to enhanced, orthogonal π-stacking interactions. We next turned our attention to difluorination of related 2-ketoester substrates

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• palladium-catalyzed direct intermolecular arylation, followed by a direct intramolecular arylation step. As the C–H bond activation of several benzene derivatives remains very challenging, the preparation of fluoranthenes from 1,8-dibromonaphthalene via Suzuki coupling followed by intramolecular C–H

• synthesis of polyaromatic compounds [6][7][8][9][10][11][12]. Since the seminal results of Fagnou et al. in 2006 on the Pd-catalyzed C–H arylation of polyfluorobenzenes [13][14][15][16], several groups have described conditions enabling the direct intermolecular Pd-catalyzed arylation of arenes [17]. In

• intermolecular Suzuki coupling with an intramolecular C–H arylation, it should be possible to access numerous fluoranthene derivatives from commercially available 1,8-dibromobenzene in a single manipulation (Scheme 1d). Here, we describe i) conditions enabling the annulative π-extension of 1,8-dibromonaphthalene

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

• CO2. Radical 12 undergoes intermolecular addition to the olefin acceptor 13 to form radical intermediate 14. Finally, under reductive conditions radical 14 can undergo hydrogen atom transfer (HAT) or sequential electron transfer and proton transfer (ET/PT) to form the conjugate addition product 15

• 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 π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• devices [1][2][3][4][5][6][7][8]. In this regard, the planar character of most (non-substituted) π-CPCs represents a challenge, as it results in very low solubility in common organic solvents due to favorable intermolecular π–π stacking interactions. This inherently hampers the purification of the target

• conformation of the thiepine ring, thus weakening the π–π stacking intermolecular interactions. Finally, solid-state S-extrusion could be triggered in a controlled way upon thermal activation of 21, as observed in thermogravimetric analysis, with the loss of sulfur detected at 223 °C to yield the planar S

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

• to be able to produce meaningful changes in the reactivity of the cage [28][29][30][31][32]. In 2018, our group reported a catalytic process to transform C60 in bis(fulleroid) derivatives [33][34][35]. This transformation encompassed a partially intermolecular Rh-catalyzed [2 + 2 + 2] cycloaddition

• explore, both experimentally and computationally, the Rh-catalyzed intermolecular [2 + 2 + 2] cycloaddition reaction between diynes and C70 as a new procedure to generate C70 bis(fulleroids). We are particularly interested in the analysis of the regioselectivity of this [2 + 2 + 2] cycloaddition. Results

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• 5. As the XRD study of the crystals showed (Figure 3), the molecular and crystal structure of the isolated compound is strongly dominated, on the one hand, by intra- and intermolecular hydrogen bonds with the participation of N, Cl, and O heteroatoms (forming an endless slightly corrugated ribbon

• the present work, we succeeded in filling this gap by growing crystals of base 5 from pure acetonitrile. It turned out that molecule 5 is capable of self-association through multiple C–H…N–H-bond-like contacts involving pyridyl C(3)H and C(4)H protons (Figure 5). These intermolecular contacts, whose

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• melting point of indigo is bifurcated intra- and intermolecular hydrogen bonding [11], and face-to-face π–π stacking of parallel aromatic rings (Figure 2) [12]. Single crystal X-ray diffraction analysis showed that the indigo molecule is almost planar and exists in the E-conformation. The central C=C bond

• the Z-isomers in comparison with the E-forms [62]. In 2018, Nagasawa and co-workers provided a detailed investigation of the influence of solvent polarity and intermolecular hydrogen bonding on the photoisomerization of N,N'-diacetylindigo (9a) by transient absorption spectroscopy [63]. In principle

• , it was already known that the intermolecular hydrogen bonding with solvent molecules may hinder the photoisomerization of indigo derivatives [46]. Nagasawa and co-workers found that the photoisomerization of 9a was inhibited by polar DMF due to formation of weak hydrogen bonds with formyl groups

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

• substrates to be submitted to the one-pot tandem transformation (Scheme 5). With only a few exceptions, the presence of ortho (R1), meta (R2), or para (R3) substituents on the benzyl moiety generally allowed the intramolecular Friedel–Crafts reaction, after the first intermolecular one in the presence of

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• intramolecular proton transfer and the methanol-mediated proton transfer, can occur. It has been described that intermediate B is more stable with enolizable electron-withdrawing groups such as esters [50] when compared to, e.g., a nitrile [49]. Accordingly, the intermolecular proton transfer pathway should be

• carbonyl moiety and for the intermolecular proton transfer in the presence of the hydrogen-donor solvent methanol. Yields and characteristic 1H, 13C, and 31P NMR shifts of compounds 2a–i. Supporting Information Accession codes CCDC 2287962 and 2287963 contain the supplementary crystallographic data for 2a

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• the following section. Small differences between the results obtained for the solutions and films appear to be due to different intermolecular interactions, which differ in solid films (between target molecules only) and solutions (between target molecules and molecules of the solvent) of the