Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• ). Overall, it was concluded that 7.1 and 7.2 first react to give 7.4 via a dark mechanochemical thiol–yne reaction; the latter is then converted to 7.3 by singlet oxygen generated in situ, by eosin Y. It is important to notice here that the reaction is proposed to proceed according to a different

Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• difluoromethylene (PhCF2) group, stand out as particularly valuable in drug design. The CF2H group can serve as a lipophilic isostere for hydroxy (OH), amino (NH2), and thiol (SH) groups, thereby enhancing the efficacy and selectivity of therapeutic agents [4][5][6]. Similarly, the PhCF2 group offers unique

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• , a plausible reaction pathway is described in Figure 6. Decarboxylation of dioxazolone in INT-22 forms the copper nitrene intermediate INT-23. The thiol then attacks the electrophilic nitrogen center of INT-23, which further leads to the formation of intermediate INT-24. Finally, the desired product

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• ][10][11][12][13][14]. Of particular interest is the difluoromethyl group, CF2H, which exhibits hydrogen bond donating character due to the highly polarized F2C–H bond (Figure 1) [14][15][16][17][18][19][20][21][22][23][24]. This functional group is often used to mimic hydroxy or thiol groups but

• that, although the CF2H group mimics hydroxy or thiol groups, it is a generally less effective hydrogen bond donor. Given that the HB donation ability of a particular functional group usually increases with increasing Brønsted acidity [49] we chose to incorporate the CF2H group into the backbone of N

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• has become an essential structural motif in medicinal chemistry due to its hydrogen-bond donor capacity, its lipophilic character, and as a bioisostere for alcohol, thiol, or amine groups [16][17][18][19]. Thus, the contribution of fluorinated compounds to pharmaceuticals has been crucial for more

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• red light irradiation [97]. Firstly, they evaluated the photoreductant role of metal-free macrocycles, H2TPP (18) and PPIX 78, in the red light-induced C–H arylation of different substrates such as furan, coumarin, thiol, pivalamide, aryl thiaether and the selenium equivalents. Use of both macrocycles

• transformations of biomolecules, such as thiol–yne reaction and decarboxylative alkynylation. The thiol–yne reaction of cyclohexanethiol (90) with phenylacetylene (89) in the presence of 1 mol % of H2TPP (18) under red LED irradiation provided the desired product 91 in up to 85% yield while the decarboxylative

• in red light-induced C–X-bond formation on biologically relevant molecules 95–97, based on a thiol–yne reaction and decarboxylative alkynylation protocol (Figure 17d). Last year, Moyano and colleagues reported on amino-functionalized porphyrins as bifunctional organophotocatalysts, effectively

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

• therapeutics, particularly in antibody–drug conjugates (ADCs). Cysteine (Cys) holds a special place in this context due to the distinctive nucleophilicity of its thiol side chain. The cysteine thiol group offers a reactive handle for site-selective modifications, allowing for the attachment of various

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

• method for the regioselective thiolation of aromatic C–H bonds by activating the thiol rather than the arene [19]. For their developed reaction, Pt electrodes were used in an undivided cell with a mixture of HFIP/DCE 3:1 at room temperature under argon. Late-stage functionalization was demonstrated for

• leads to an intermediate product, which is then deprotonated, generating the thiol radical. This allowed for the preparation of the para-thiolation product (Scheme 11). Sulfonamides are an important class of bioactive molecules. In 2021, the Waldvogel group disclosed the first C(sp2)–H functionalization

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• ring-opening reaction with the same thiol (entries 6–8 in Table 3). It is interesting to note that a longer reaction time was required for these substrates which would be the major reason for the relatively low diastereomeric ratio (especially in the case of entry 8 in Table 3) while the CHF2

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• corresponding thiols. The starting reagents such as substituted 1,3,4-oxadiazole-2-thiols and 4H-triazole-3-thiols are characterized by thiol–thione tautomerism, therefore their reactions with 3,5-di-tert-butyl-6-methoxymethylcatechol can proceed at the sulfur or nitrogen atom. In the case of mercapto

• [25]. A feature of mercapto-substituted heterocycles is the possibility of their existence in two tautomeric forms: thiol or thione [26][27]. The ability to tautomeric transformations affects their biological activity and allows the use of these molecular blocks to design compounds with different

• corresponding thiol [35][36][37][38], in the nucleophilic substitution reaction in the aromatic ring of catechol [39][40] or under electrochemical conditions [41][42][43]. An anodic activation of catechols in the presence of a thiol leads to S-functionalized catechols with triazole, triazine, pyrimidine

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• interrupted CuAAC mechanism [65]. The thiotriazole product of this reaction, which is indistinguishable in the protein-level downstream analysis, is formed by coupling between protein free thiol groups and the triazole–copper adduct (Figure 4). However, its formation can be avoided by eliminating the free

• , in this case, the cysteine thiols were derivatized and the cysteine C–S bond was previously described to be susceptible to fragmentation, the fragments containing the thiol provide the information on the structure of the modified amino acid side chain [107][108]. Although the study was focused on the

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• guanidine motif in AA-3 compared to simple AA-1. Alterations in the thiol structure within thiomalonates significantly impact their stability and reactivity, thereby influencing both reaction efficiency and stereochemical outcome, as demonstrated in the case of catalysis employing bifunctional hydrogen bond

• adduct. Hence, after 24 hours up to 9% of sulfa-adduct was formed (see Supporting Information File 1 for details). Unfavorable in this case is the formation of ketene via thiol elimination [40], leading to the formation of a mixture of products where the thia-Michael adduct predominates over the desired

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• ][62][63][64], we conducted research on their organic reactions in water and reported some good results, such as thioacetalization using ketene dithioacetals as odorless thiol equivalent [65], Friedel–Crafts alkylation of cyclic ketene dithioacetals with alcohols [66], the hydrolysis of chain α-oxo

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• a pioneering study, Ito and Saegusa et al. reported the radical addition of thiols to isocyanides (Scheme 2) [27]. Thermal decomposition of AIBN as a radical initiator generates the 2-cyano-2-propyl radical ((NC)(CH3)2C•), which abstracts hydrogen from the thiol (R’SH) to form the thiyl radical (R’S

• •). The formed R’S• adds to isocyanide (RNC) to generate imidoyl radical intermediate 2 (E = R’S), which abstracts hydrogen from thiol to give the corresponding thioformimidate 3 (E = R’S) with regeneration of R’S•. Thus, the hydrothiolation of isocyanides with thiols proceeds by the radical chain

• by ESR measurement [37]. Similar to the thiol addition to isocyanides, disubstituted phosphines (R’2PH) induce radical addition to isocyanides in the presence of AIBN as a radical initiator yielding the corresponding iminoformyl phosphines, R’2P–CH=NR, (12, R = c-C6H11 or n-C6H11, E = Et2P) in good

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

• 47, can be accessed from polyfunctional hydrazine derivatives via multicomponent reactions. For the preparation of pyrazoles 47, 4-amino-5-hydrazinyl-4H-1,2,4-triazole-3-thiol (44), phenylacyl bromides 45, and benzoylacetonitriles 46 were chosen as starting materials (Scheme 13) [67]. Thereby

• , benzoylacetonitrile and the hydrazinyl moiety constitute the pyrazole nucleus, while phenylacyl bromide condenses with the thiol and amino groups to form the thiadiazinyl moiety. In addition to bromoacetylchromenone, phenylacetyl bromide can also be used as an alternative starting material. 1,3-Dielectrophilic β

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• aromatic substitution; phenol; thiol; Introduction Diketopyrrolopyrroles (DPPs) are a class of organic pigments discovered by serendipity in the 1970s [1][2]. Generally, N-unsubstituted DPP derivatives exhibit high melting points, low solubility in most solvents, and strong absorption in the visible

• excellent nucleophiles and generally react under mild conditions, resulting in the substitution of the 4-F atom of the pentafluorophenyl groups. In this case, reactions with thiols were performed in dry DMF and K2CO3 was used as the base. Three different thiols were tested: pyridine-4-thiol, pyridine-2

• -thiol and 4-(acetylamino)benzenethiol. The reaction with pyridine-4-thiol yielded a mixture of the di- and monosubstituted compounds 3a and 4a in 51% and 23% yields, respectively. Conversely, for the reaction with pyridine-2-thiol, exclusively produced the disubstituted compound 3b in an 85% yield

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• times dehydrated was identified. Cyclization reactions introduced thioether cross-links between dehydrated Thr/Ser residues and specific cysteine thiol groups. However, due to identical masses of dehydrated linear peptides (lacking thioether rings) and cyclic forms (containing Dhb and Dha rings), a

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• studies to establish function, such as thiol S-methylation by SchX in the biosynthesis of the thiopeptide Sch40832, if it is identified at all [135][136]. In this section two S-MTs will be discussed. The first MT is involved in the biosynthesis of an unidentified metabolite in Candidatus Entotheonella

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

• phosphoranyl radical intermediate then undergoes β-cleavage, giving rise to a benzylic radical and triphenylphosphine oxide. A terminal hydrogen atom transfer (HAT), facilitated by an aryl thiol, results in the formation of the desired product with concurrent formation of the thiyl radical. The reduction of

• the thiyl radical by [Ir(II)] generates a thiolate anion and [Ir(III)]. Finally, the thiolate anion is converted to the aryl thiol via proton transfer to complete the catalytic cycle. In 2021, MacMillan and co-workers [55] introduced a cross-coupling reaction of alcohols with aryl halides through

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• the homobenzylic position, engaging in an anti-Markovnikov manner with a formal chloride nucleophile. The ultimate step involves hydrogen atom transfer (HAT) with thiol 148, culminating in the formation of the desired product 147. Therefore, the generation of the vinyl radical cation plays a pivotal

• combination with a chloride anion, regenerates the initial acridinium catalyst 161. The thiyl radical is formed through hydrogen atom transfer (HAT) with thiol 150, thus completing the second catalytic cycle. Hence, the key distinction from Nicewicz's work is that in the Ritter protocol, chloride undergoes

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

• the p-fluorine atom in the pentafluorophenyl substituent with an azide functionality which upon reduction with SnCl2 resulted in the formation of the corresponding porphyrin with an amino group. Pentafluorophenyl-substituted A3B-porphyrins were studied and transformed to thiol and amino-substituted

• 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

• studied the nucleophilic substitution reactions of the p-fluorine atom in the pentafluorophenyl-containing porphyrin 6 with thiol-substituted compounds such as 2-mercaptoethanol (15), cysteamine hydrochloride (16), and 3-chloro-1-propanethiol (17) as shown in Scheme 5. The reactions proceeded readily in

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

• % purity) [26] provided a more selective reaction, no water-based work-up was needed and the pure product was obtained by simple recrystallization from ethanol in yields up to 88%. The oxidation step thiol → sulfoxide was fast and full conversion to the intermediate was achieved in one hour for most

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• quantities of the most active compounds for advanced biological testing. Pleasingly, our four-step approach using a potassium O-ethyl dithiocarbonate-mediated formation of thio intermediates 11a–c (thiol–thione tautomers) with subsequent sulfur removal using iron powder in acetic acid [19] proceeded smoothly

• 11b as thiol–thione tautomer consisting of 6-bromo-5-(2-fluorophenyl)[1,3]thiazolo[4,5-b]pyridine-2-thiol and 6-bromo-5-(2-fluorophenyl)[1,3]thiazolo[4,5-b]pyridine-2(3H)thione (17.20 g, 97%). 1H NMR (400 MHz, CDCl3, δ) 9.96 (br s, 1H), 8.01 (s, 1H), 7.50–7.44 (m, 1H), 7.41–7.38 (m, 1H), 7.29–7.25 (m

• , 1H), 7.19–7.15 (m, 1H). The thiol–thione tautomer 11b (14.55 g, 42.64 mmol, 1.0 equiv) was dissolved in acetic acid (200 mL), and iron powder (35.71 g, 639.61 mmol, 15 equiv) was carefully added in portions. The resulting reaction mixture was stirred at 100 °C for 10 h. After full conversion

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