Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• stoichiometric quantities of a copper reagent [3]. This pioneering work, known as the “classical Ullmann reaction”, was extended by Ullmann and Goldberg to enable the C–N and C–O bond formation [4][5][6]. Subsequently, key developments in Cu-catalyzed cross-coupling reactions were achieved, including the

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• -disubstitution on the diaryliodonium salts. The reaction mechanism involves the deprotonation of the phenol 61 and diaryliodonium salts 73 via base under high temperature to get phenolate I and benzyne intermediate II, respectively. The phenolate nucleophile reacts with the benzyne intermediate to create a C–O

• bond, leading to the formation of the carbanion intermediate III. Lastly, this intermediate is protonated by bicarbonate to yield the final product 74 (Scheme 30). Furthermore, Wang and his team introduced a novel method to synthesize ortho-iodo diaryl ethers 77 using intramolecular aryl migration in

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• remarkable 96%ee yielded by the catalyst. Schematic representation of an (A) 2D and a (B) 3D volcano plot. The abbreviation “cat.” stands for catalyst. (A) Structure of PO annotated with the C–O bond distances and electron densities at the BCPs. BCPs are indicated by green spheres and the ring critical point

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• functionalization method where primary, secondary, and tertiary alkyl radicals can be readily generated through the sequential anodic oxidative fragmentation of alkyl carbazates, enabling the functionalization of N-heteroarenes [7]. This transformation is particularly valuable as the cleavage of the C–O bond to

• celestolide showed high yields and good selectivity (Scheme 9). The Lei group also disclosed another C(sp3)–H functionalization involving C–O-bond formation [18]. The reported method allows the straightforward preparation of α-acyloxy sulfides from ubiquitous carboxylic acids and sulfides, providing an

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• used as substrate, selective C–O bond cleavage, followed by fixation of carbon dioxide, occurred at the benzylic C(sp3)–O bond rather than the C(sp2)–O bond on the phenyl ring to give the corresponding diphenylacetic acid 2h in 45% yield. Not only a secondary alcohol but also a tertiary alcohol was

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

• substrate 1c may act as an electrophilic center, forming a C–O bond with the alkenyl group to give the isochromen-1-one oxime product 2c'. When wet HFIP was used as the solvent, the reaction followed a different pathway. HFIP, a strong hydrogen bonding donor [26][27][28], interacts with the amide moiety of

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

• bond formation to afford the acyloxylation product was observed, and favoured when using directing groups with less steric bulk. This product had the opposite stereochemistry to the fluorination product suggesting it occurred via a competitive SN2 pathway. This is supported by the selectivity for C–O

• on the arene were unsuccessful. Without substituents on the ring, aryl C–H activation and subsequent C–O bond formation occurred along with benzylic fluorination (7) (low efficiency). The presence of a p-methoxy group resulted in a switch in selectivity to acyloxylation 8’ as the major product. The

• was effective for the stereoselective fluorination of benzylic positions ortho to aldehyde substituents (Figure 9). The choice of a bulky amino, transient, directing group dictated the stereochemical outcome and promoted the C–F reductive elimination through an inner-sphere pathway. A competitive C–O

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

• that can produce reactive radicals by homolysis of the C–O bond. These radicals can then go through a variety of transformations that are beneficial for the construction of synthetic materials that are otherwise difficult to access. This study summarizes current developments in the use of organic

• photocatalytic and electrochemical deoxygenation of acids and alcohols has attracted significant attention as the strategic cleavage of the C–O bond is quite challenging and opens up new possibilities for constructing useful compounds [12][13][14]. The use of photogenerated carbon-centered radicals, such as acyl

• and acyl radicals and maintaining a high degree of selectivity with respect to the desired outcome are key obstacles to the growth of alkyl and acyl radical chemistry. With this in mind, the emergence of new chemical transformations involving radicals generated via C–O bond cleavage by visible light

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

• assigned to the charge transfer band of the C=S bond in t-Bu-FIDS, which was stronger than that of the C=O bond in t-Bu-FIDO [30]. Interestingly, the maximum absorption band observed in t-Bu-FIDO at 432 nm, which is a characteristic feature of 58π-fullerene derivatives with a 1,2-addition pattern, was

• -addition pattern of t-Bu-FIDS (Figure 2a,b). The shortest π–π distance between the two fullerene molecules of t-Bu-FIDS in a unit cell was 3.14 Å, while that in t-Bu-FIDO was 2.974 Å [19]. The C=S bond length was 1.627 Å and was clearly longer than the C=O bond in t-Bu-FIDO. We consider that this longer

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

• Naziha Tarannam,
• Prashant Kumar Gupta,
• Shani Zev and
• Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

• (GPP, FPP, GGPP) undergo highly complex cyclisation cascades forming terpenes and terpenoids that often have great structural complexity. For class I terpene synthases this multistep process is initiated by a heterolytic C–O bond cleavage, separating the diphosphate and isoprenoid ion pairs [3][4]. The

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• the C=O bond. In this manner, the asymmetric induction results in the restricted addition of nitromethane influenced by imidazolidin-4-one moieties. The higher enantioselectivity of complexes of the ligands with cis-cis configuration could be explained by the fact that the larger (RL) alkyl group is

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

• the C=O bond. Thus, an innovative approach on nanocatalysis was introduced, incorporating solid grinding in catalyst-free conditions with the challenge of a high catalyst loading and lack of aliphatic aldehydes or ketones being utilized as substrates for the formation of their respective BIMs [118

Nucleophilic functionalization of thianthrenium salts under basic conditions

• Xinting Fan,
• Duo Zhang,
• Xiangchuan Xiu,
• Bin Xu,
• Yu Yuan,
• Feng Chen and
• Pan Gao

Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26

• accessible and have significant importance in the pharmaceutical industry, positioning them as appealing candidates for C(sp3) coupling due to their availability as a common chemical feedstock. However, due to the high bond dissociation energy of the C–O bond and the poor leaving ability of the hydroxy group

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• possible, that the N-benzyl group attached to the 1,2,3-triazole moiety is partially removed under these conditions and/or that even the C–O bond connecting the 1,2,3-triazole part with the aminopyran part is reductively cleaved since this bond also has benzylic character. In earlier investigations with

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

• of ethers to obtain symmetric and asymmetric 1,1-bis-indolylmethane derivatives (Scheme 23) [84]. The reaction proceeds through the tandem oxidative coupling of the C–O bond and cleavage of the C–H bond. Fe plays a dual role in catalysing the C–C bond coupling and C–O bond cleavage as Lewis acid

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

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• split over two positions yielding in total 5.75 mol of water per CO2. The hydration is similar to that of native α-CD [13] and that of the krypton inclusion complex which has 5.28 water/Kr [14]. The CO2 molecule refines with an optimal occupancy of 0.84 and linear geometry (178.2(6)o) with C–O bond

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• and NaCl. Only one example was reported for this class of the synthesis via C–C bond formation (Scheme 10) [30]. 1.2 Synthesis via C–O bond formation Halocyclization has been widely applied in the syntheses of phostone and phostine derivatives via C–O bond formation [13][17]. Both bromo and iodo

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• the 3d5/2 orbital was 280.94 eV, which corresponds to Ru(0). Double bonds π C=C were also detected in the sample at 285.49 eV, reflecting the presence of the PPh3 groups, but no C=O double bonds could be observed (while the presence of a C=O bond was clearly observed on the XPS spectrum of comp4 (see

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

• into the C–O bond of the oxabicyclic alkene 30a to afford the σ-allyl intermediate 38 which can isomerize to the more stable π-allyl intermediate 39. Addition of the α-amino radical to the Ni(II) center generates the Ni(III) complex 41. Reductive elimination, followed by protodemetalation, leads to the

• (Scheme 19) [62]. Similar reactivity trends were observed in both accounts. Mechanistically, the transformation was proposed to begin with the coordination of Cp*RuI to the exo face of the bicyclic alkene. Oxidative addition into the C–O bond, which is proposed to be the enantiodetermining transition

• final product, and previously reported Rh-catalyzed ARO reactions, the authors hypothesized the reaction begins with the oxidative addition of the Rh(I) catalyst into the bridgehead C–O bond of the oxabenzonorbornadiene producing 148 which is considered the enantiodetermining step. The isocyanate anion

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• OH groups from water molecules), CH bonds (especially from the CH2 and CH3 groups), bands corresponding to the aromatic CC bonds, and the carbonyl C=O bond. The most relevant FTIR band for these compounds is the asymmetric stretching vibration of the C=O bonds, νasC=O, which appears around 1633–1651

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• a semipinacol rearrangement leading to 95, followed by subsequent cyclization to natural products guignardone A (96) and C (97). This process involved 1,2-allyl migration and C–O bond formation through a semipinacol rearrangement and a cyclodehydration cascade reaction (Scheme 8). Following the same

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• , respectively. At this stage, we started to investigate alternative methods to cleave the amide via reduction. Achieving selective C–N-bond cleavage of amides under reductive conditions is still a largely unsolved problem since a C–O-bond cleavage is typically the preferred mode of reactivity, especially when

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• reports found in the literature suffer from the requirement of hazardous intermediates and harsh reaction conditions. Here, we report a new six-step synthesis for c1G base, starting from 6-iodo-1-deazapurine. The key transformations are copper catalyzed C–O-bond formation followed by site-specific

• 3,4-dihydropyran in dimethylformamide to obtain the corresponding tetrahydropyranyl-protected amine 17. Subsequently, a copper-catalyzed C–O bond formation at C6 using benzyl alcohol in the presence of caesium carbonate, copper(I) iodide, and 1,10-phenanthroline furnished benzyl ether 18 in excellent

• ) starts from the tetrahydropyranyl-protected 6-iodo-1-deazapurine 17 which was converted into the O6-benzyl derivative 31 using the copper-catalyzed C–O-bond formation as described above (Scheme 6). Without purification the crude product was treated with hydrochloric acid in methanol to remove the