Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• , combining the specificity of antibodies with the potency of cytotoxic drugs to enhance therapeutic efficacy while minimizing off-target effects. The development of new chemical methods for bioconjugation is essential to generate ADCs and to optimize their stability, efficacy, and safety. Traditional

• proteins. By harnessing light to drive chemical transformations, photoredox techniques can facilitate the synthesis of antibody bioconjugates. This perspective will discuss the drive to develop and empower photoredox methods applied to antibody functionalization. Keywords: antibodies; bioconjugation

• covalent bioconjugation. Effective bioconjugation has been dramatically facilitated by the development of robust bioorthogonal reactions, which has revolutionized the field of chemical biology [17]. A bioorthogonal reactive group can be introduced into proteins via direct chemical coupling on specific

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

• )–H functionalization C–N coupling reaction by developing an electrochemical method for the bioconjugation of tyrosine in proteins/polypeptides with phenothiazine residues, achieving excellent site- and chemoselectivity (Scheme 4a). This method was inspired by an earlier work from the Gouin group

• , which reported the merger of electrochemistry and bioconjugation in 2018 (Scheme 4b) [11]. In 2020, Zheng and coworkers developed an interesting iodoamination of indoles using unactivated amines and benzotriazoles [12]. This difunctionalization reaction was carried out in an undivided cell with an RVC

• and cross-coupling of different kinds of amines for approaching symmetric and unsymmetric imines [76]. This method achieved the bioconjugation of several amino acids with benzylamine, the use of phenylalanine (Phe), serine (Ser), and isoleucine (Ile) as substrates led to 85%, 59%, and 29% yield

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• the field of bioconjugation and materials research. We previously reported a regioselective double addition of organic azides to octadehydrodibenzo[12]annulene derivatives with electron-rich alkyloxy substituents. In order to increase the reaction rate, electron-withdrawing substituents were

• azide–alkyne cycloaddition; Introduction The strain-promoted azide–alkyne cycloaddition (SpAAC) is one of the most representative metal-free click chemistry reactions [1][2][3][4][5]. SpAAC has been mainly employed in bioconjugation in the fields of chemical biology and medicinal chemistry due to its

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• carborane A3B-porphyrin were also synthesized based on the amino-substituted A3B-porphyrin. The structures of the prepared carboranylporphyrins were determined by UV–vis, IR, 1H, 19F, 11B NMR spectroscopic data and MALDI mass spectrometry. Keywords: bioconjugation; carboranes; fluorine; porphyrin; SNAr

• conjugates with functionalized linker groups suitable for bioconjugation or which may be efficient for PDT and BNCT improvement. Results and Discussion Synthesis Nucleophilic substitution reactions of the four p-fluorine atoms in 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (1) are well studied [15][16

• has become one of the most popular route for the site-selective modification of cysteine residues in bioconjugation technology. We suppose that the maleimide group in porphyrin 11 is a useful target for thiol conjugation via Michael addition reactions [44]. This also concerns biotin-conjugated organic

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• yields, quick reaction times, and excellent regioselectivity, the "click" cycloaddition reaction has enabled the synthesis of several compounds with a wide range of applications in a variety of sectors, including bioconjugation [5][6] drug development [7][8], glycoscience [9][10], porphyrin chemistry [11

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• isoxazoles, an important class of structures found in numerous bioactive natural products and pharmaceuticals. Producing good to excellent yields in short reaction time in aqueous media, our method has the potential for significant applications in biological systems (e.g., click reactions, bioconjugation

Stepwise PEG synthesis featuring deprotection and coupling in one pot

• Logan Mikesell,
• Dhananjani N. A. M. Eriyagama,
• Yipeng Yin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2021, 17, 2976–2982, doi:10.3762/bjoc.17.207

• obtained. However, for many other applications, which include as linkers in organic synthesis and bioconjugation [8], as ingredients in nanomedicines to stabilize nanoparticles and to assist nanoparticle cell entry [9][10][11], and as PEGylation agents to stabilize drugs based on biologic molecules such as

• obtained. We expect that the one-pot PEG elongation approach will be helpful to make monodisperse PEGs more affordable and has a positive impact in areas such as bioconjugation and nanomedicine where monodisperse PEGs are needed. A comparison of the new PEG synthesis method with a typical known PEG

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• Mendal [3], many studies have been dedicated to better understanding of the concept and expanding its scope to be applied in various fields of chemistry including bioconjugation [4], drug discovery [5], materials science [6][7][8][9] and so on [10]. The development of the use of light in click chemistry

• has set a milestone as a new and effective method for the synthesis of macromolecules [11]. Initiation of this reaction photocatalytically provides many advantages for the synthetic methodologies including bioconjugation, labeling, surface functionalization, dendrimer synthesis, polymer synthesis, and

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• the mechanochemical approach (the B & B, ball milling for boronic acid conjugation) as bioconjugation strategy for the labeling of biocompatible carbohydrates. Fluorescent labeling is of key importance to follow up the fate of molecules and (nano)materials inside cells and in the human body. In this

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• similar to the free acids. The future promising candidates which were expected to emerge in the course of synthesis and screening could be eventually transformed to the corresponding carboxylic acids possessing higher solubility in aqueous buffers and reactive groups required for bioconjugation. Results

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• –protein interactions [19][20], CRISPR genome editing [21][22][23], DNA data storage [24][25], synthetic biology [26], bioconjugation [27] and others [28][29][30]. These applications frequently require modified ODNs that contain a wide variety of functional groups including those that cannot survive known

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• such a mild and selective oxidation. MacMillan and co-workers have recently developed a method for the bioconjugation of peptides by radical decarboxylation of the C-terminus of peptides and subsequent Giese-type addition to Michael acceptors. This is performed under blue light irradiation, using

• immediately obvious application of this bioconjugation to biochemistry and molecular biology as a tool for protein labelling, it could also be used as a convenient tool for peptide chemists in medicinal chemistry programs for modification of peptides. 2.2 C(sp2)–C(sp2) bond formation Suzuki–Miyaura and

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

• Takao Shoji,
• Hiroki Fukutomi,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

• directly conjugated. It should be noted that there is no need to pre-install artificial functional groups and undesired and unpredictable perturbations possibly caused by bioconjugation can be minimized. Keywords: alkyl chain soluble supports; artificial bioconjugates; naturally occurring linkages; 5

• bioconjugation product 4 and basic deprotection gave the native form 5 with a naturally occurring linkage in 70% yield over 5 steps. The impurities can reasonably be assigned as the hydrolized and/or oxidized products of the 5’-activated supported trinucleotide 2 [75]. In order to investigate the generality of

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• reaction conditions together with very high and reverse regioselectivity and efficiency (in most cases 85–99% yields) makes the CuSAC reaction a very good alternative to the well-established azide–alkyne click-reaction [117] useful not only in classical organic synthesis but also in bioconjugation

Synthetic mRNA capping

• Fabian Muttach,
• Nils Muthmann and
• Andrea Rentmeister

Beilstein J. Org. Chem. 2017, 13, 2819–2832, doi:10.3762/bjoc.13.274

• for additional bioconjugation reactions. A combination of chemical 5′-cap analogue synthesis followed by enzymatic modifications has further allowed conferring novel functionalities (e.g., photo-crosslinking moieties) which were previously not easily accessible. Combining enzymatic modification at

Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX

• Gergely L. Tolnai,
• Jonathan P. Brand and
• Jerome Waser

Beilstein J. Org. Chem. 2016, 12, 745–749, doi:10.3762/bjoc.12.74

• Givaudan, Chemin de la parfumerie 5, 1214 Vernier, Switzerland 10.3762/bjoc.12.74 Abstract The selective functionalization of peptides containing only natural amino acids is important for the modification of biomolecules. In particular, the installation of an alkyne as a useful handle for bioconjugation

• modified reaction conditions (10 mol % AuCl(SMe2), three equivalents TIPS-EBX (1a) and 2 mol % trifluoroacetic acid as co-catalyst) [39]. They also demonstrated that the obtained silylalkyne products can be easily deprotected with fluoride sources to allow bioconjugation via cycloaddition with azides

• requiring the installation of non-natural amino acids, the transformation will be highly useful for bioconjugation. A current limitation of the developed alkynylation reaction is the requirement for organic solvents. Investigations are currently ongoing in our laboratory for the development of water

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

• Zhan-Jiang Zheng,
• Ding Wang,
• Zheng Xu and
• Li-Wen Xu

Beilstein J. Org. Chem. 2015, 11, 2557–2576, doi:10.3762/bjoc.11.276

• reactions are ideal for bioconjugation where no additional metal is required [31]. In 2012, Beal and co-workers incorporated the terminal alkyne and the activated cyclooctyne with two amide formation reactions [32], and then the SPAAC reaction was performed between the cyclooctyne 35 and the azides under

Copper catalysis in organic synthesis

• Sherry R. Chemler

Beilstein J. Org. Chem. 2015, 11, 2252–2253, doi:10.3762/bjoc.11.244

• . Some of the most highly cited papers of all time on this topic are reviews on conjugate addition, cross-coupling, and [3 + 2] “Click” reaction applied to bioconjugation. The growth in copper-catalyzed organic reactions may be driven by a couple of factors. First, copper chemistry is incredibly diverse

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II)–EDA (EDA = ethylenediamine) complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer

• photogenerated copper(I) being very reactive. On irradiating aqueous reaction mixtures containing 1 mol % of 1 at 365 nm (TLC lamp) for 1 h, click reactions were shown to proceed to full conversion. Keywords: benzophenone photosensitizer; bioconjugation; click chemistry; copper; photoreduction; Introduction

• . A major application of the CuAAC concerns bioconjugation reactions, i.e., the covalent modification of biomolecules [6]. Such reactions typically imply water-soluble alkyne and azide reactants and should thus be performed in an aqueous medium using a water-soluble catalyst. Important limitations for

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• because it reduces nonspecific interactions and also complicates the bioconjugation. To deal with this problem, we adjusted a surface chemistry route including radical generation at the PEG backbone by UV irradiation [15]. This enabled the addition of unsaturated carboxylic moieties onto the PEG scaffold

C-5’-Triazolyl-2’-oxa-3’-aza-4’a-carbanucleosides: Synthesis and biological evaluation

• Roberto Romeo,
• Caterina Carnovale,
• Salvatore V. Giofrè,
• Maria A. Chiacchio,
• Adriana Garozzo,
• Emanuele Amata,
• Giovanni Romeo and
• Ugo Chiacchio

Beilstein J. Org. Chem. 2015, 11, 328–334, doi:10.3762/bjoc.11.38

• assumes particular interest according to its easily access and the well-known biological activity of many derivatives. In these last years, in fact, triazoles have gained considerable attention in medicinal chemistry, bioconjugation, drug-delivery, and materials science [33][34][35][36][37][38]. Moreover

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• pharmaceutical areas not only to enhance water solubility and reduce immunogenicity but also to increase in vivo circulation half-life by preventing enzymatic degradation and renal clearance [4]. Numerous examples of bioconjugation with PEG have been reported including, among others, proteins located in

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• ligands [45]. The authors used the newly developed ligand system in a bioconjugation reaction with a virus. The exterior surface of the coat protein of cowpea mosaic virus was labelled with 60 azide groups as shown in Scheme 3 [45]. Then, the reaction with an alkyne-functionalized dye was carried out in

• CuAAC in the bioconjugation reaction with cowpea mosaic virus (Scheme 3) [45], water-soluble derivatives such as THPTA [70][71][72][73][74][75][76][77][78], BTTP [79], BTTAA [74], BTTES [68], and BTTPS [79] have been applied in CuAAC reactions (Figure 1). Closely related to tris(triazolylmethyl)amines

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• . Interestingly all these compounds are actually pro-drugs hence the common structural features can be rationalised as the molecules undergo an acid-catalysed Smiles-rearrangement prior to bioconjugation to ATPases (Scheme 6). Most of the synthetic routes towards the embedded pyridine heterocycle in these

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• applications in numerous other areas of modern chemical sciences, such as bioconjugation [13], supramolecular chemistry, [14] and polymer sciences [15]. Probably the most useful and powerful procedure for the synthesis of 1,2,3-triazoles is the Huisgen 1,3-dipolar cycloaddition of organic azides with