Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• derivatives lack a covalent attachment handle. By making use of drug conjugates, toxic payloads such as cryptophycins can be selectively delivered to the target site. We present the synthesis of two conjugable cryptophycins with amino groups in unit B, representing potential payloads for drug conjugates

• of N-alkylation on the non-chlorinated unit B derivatives. Results and Discussion For the synthesis of unit B derivatives with amino groups instead of the naturally occurring methoxy group ᴅ-phenylalanine served as the fundamental substrate (Scheme 1). Nitration [23] followed by methyl ester

• values of the primary (IC50 (CCRF-CEM) = 580 pM) and tertiary (IC50 (CCRF-CEM) = 54 pM) amine derivatives (Figure 1B) [20][35], showing a strict increase in cytotoxicity with increasing degree of aniline methylation. The same trend was also observed for unit D derivatives modified with amino groups [19

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• -donating bis(methoxyphenyl)amino groups further improved the PLQY to 73%, displaying a mixed excitonic and charge-transfer character [22]. Additionally, the functionalization of BPP with two methyl benzoate groups enabled the development of hole-selective contact, which was applicable in significantly

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• VIII (named BBX), and investigated its reactivity on the α-amination of indanone-based β-ketoesters (Scheme 1) [4]. Very recently, Minakata’s group also reported iodine(III) reagents with transferable amino groups, particularly a benziodoxolone bearing a transferable NH2 group (IX) [20]. HIRs have been

• benziodoxol(on)es can be found in the literature, including reagents featuring cyclic aliphatic amine moieties (III) [15], phthalimidates (IV) [16], and carbazoles (VII) [19]. Minakata and co-workers proposed an innovative approach for transferring imine groups using iodane-containing (diarylmethylene)amino

• groups (V), which proved to be useful in the transfer of imine radicals [17]. Bolm et al. contributed also to this topic by introducing a sulfoximidoyl-containing benziodoxolone (VI) [18]. Recently, our group disclosed the first HIRs bearing a primary amine moiety, the benzylamine benziodoxolone reagent

Ceratinadin G, a new psammaplysin derivative possessing a cyano group from a sponge of the genus Pseudoceratina

• Shin-ichiro Kurimoto,
• Kouta Inoue,
• Taito Ohno and
• Takaaki Kubota

Beilstein J. Org. Chem. 2024, 20, 3215–3220, doi:10.3762/bjoc.20.267

• existence of a substituted benzenoid chromophore was suggested by the UV absorption maximum at 258 nm. The presence of hydroxy and/or amino groups and a carbonyl group was indicated by IR absorptions at 3337 cm−1 and 1671 cm−1, respectively. The analysis of the HSQC spectrum, along with the 1H and 13C NMR

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• first example of the synthesis of CD-based rotaxanes was reported by Ogino in 1981 (Scheme 1A) [36]. The hydrophobic interaction between the α-CD cavity and the alkyl chain of α,ω-diaminoalkane yielded the inclusion complex structure, and the ligand exchange between the amino groups on the axle ends and

• structure in the early days. Rotaxane bearing a dumbbell comprising only covalent bonds was first reported by Harada and co-workers in 1997 (Scheme 1B) [38]. In this system, the end-capping reaction was based on the nucleophilic substitution of the amino groups on the axle ends. Afterward, such nucleophilic

• synthesis, Harada and co-workers reported the end-capping reaction based on nucleophilic substitution by the amino groups on axle ends (Scheme 2) [43]. Similarly, other highly efficient reactions have been performed as end-capping reactions to produce polyrotaxane [13][14][15]. In addition to the simple

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• short-axis direction of the electron-deficient aromatic ring significantly retards the internal conversion via the formation of H···F hydrogen bonds, leading to a marked blue fluorescence in the crystalline state (Figure 1b) [17][18][19][20]. Recently, the introduction of N,N-disubstituted amino groups

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• %) are nitrogen-containing organic compounds, with many featuring amino groups adjacent to a stereogenic centre. Some reports suggest that 75% of all FDA-approved compounds are alkaloids [2]. The industrial production of amines on a million-ton scale underscores the significance of methods for their

Cage-like microstructures via sequential Ugi reactions in aqueous emulsions

• Rita S. Alqubelat,
• Yaroslava A. Menzorova and
• Maxim A. Mironov

Beilstein J. Org. Chem. 2024, 20, 2078–2083, doi:10.3762/bjoc.20.179

• polysaccharides [18]. Therefore, to stabilize such structures, the Ugi reaction in water was chosen, for which this particular pH value range is optimal [19]. The amino groups of chitosan and the carboxy groups of CMC reacted with each other and formed a stable structure that was no longer sensitive to changes in

• of 1:10 relative to the number of moles of amino groups in the chitosan. For the Ugi reaction to proceed to completion in water, it was ensured that the pH value did rise above 5.5. It should be noted that the reaction proceeded very quickly under these conditions, being completed within 2–3 min

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

• , 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

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• corresponding to the acidic protons in the spectra of the salts excluded protonation of the pyridyl or amino groups. The downfield shift of the signals of both the N-aryl ring (for 0.5–1 ppm) and the pyridyl moiety (for more than 1 ppm) confirmed the positive charge delocalization over both N atoms and the

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

• -dioxaoctane (21) and 1,13-diamino-4,7,10-trioxatridecane (22) in DMSO at 70 °C for 30 min to form amino-conjugates 23 and 24 in 71 and 84% yield, respectively, containing ethylene glycol linkers with terminal primary amino groups (Scheme 6). The presence of ethylene glycol residues in bioactive molecules is

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• molecular structure of 5c was also determined using X-ray crystallography (Figure 4). We assumed that the scope of the reaction shown in Scheme 3 could be expanded via replacement of one of the amino groups of o-phenylenediamine by another strong nucleophilic center. It was earlier found [23] that

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• 1D and 2D NMR spectroscopic data. The 1H NMR spectrum in DMSO-d6 showed signals of two amino groups at 6.15 and 5.46 ppm. The HMBC spectrum demonstrated diagnostic cross peaks between one of these groups (6.15 ppm) and carbons at 148.8 ppm (C) and 143.9 ppm (CH), and the other group (5.46 ppm

• its somewhat anti-aromatic character. Obvious aromaticity of the pyrazole rings is confirmed by the NICS(0) values of −12.64 ppm. Macrocycle 5 has various reactive centers, including two amidrazone fragments with primary amino groups, which makes it possible to modify it in many ways [51][52][53][54

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• in the presence of sodium metabisulfite (Na2S2O5) [29] to obtain the corresponding substituted benzimidazoles (III) in essentially quantitative yield (Scheme 1). In the absence of Na2S2O5, but under otherwise similar conditions, we obtained in some cases the imines in which one of the amino groups

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Cyanothioacetamides as a synthetic platform for the synthesis of aminopyrazole derivatives

• Valeriy O. Filimonov,
• Alexandra I. Topchiy,
• Vladimir G. Ilkin,
• Tetyana V. Beryozkina and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2023, 19, 1191–1197, doi:10.3762/bjoc.19.87

• presented in the literature. These syntheses are multistage [17] or are essentially a transformation of the structure of the previously obtained pyrazoles [18] (Scheme 1A). Methods for the synthesis of pyrazoles containing thioamide and amino groups in a molecule are even less developed than methods for

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• of CS-TPE, i.e., the hydrophilicity of the protonated amino groups in an acidic environment combined with the hydrophobicity of the TPE units. Their morphologies under alkaline conditions were studied to investigate the effect of pH on the stability of the CS-TPE nanoparticles. When the pH of the

• solution was increased to 10.4, the nanoparticles collapsed and aggregated (Figure 3d–f), which could be attributed to the poor solubility of the samples bearing neutral amino groups of CS-TPE under alkaline conditions, leading to the accumulation of molecular chains. The pH-responsive behavior of CS-TPE

• carboxylate functionalities of TBTQ-C6 and the amino groups of CS-TPE. Therefore, we investigated the pH-responsive behavior of the TBTQ-C6/CS-TPE complexes by transmittance and TEM measurements. As displayed in Figure 6e and 6f, the optical transmittance increased when the pH of the solution of TBTQ-C6/CS

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• correlation from the imidazole proton at δH 6.55 to the downfield carbon at δC 146.8 indicated a 2-amino substituted histamine moiety [19]. Finally, the unassigned exchangeable protons at δH 10.11 and 7.36, were assigned to phenol (4-OH) and amino groups (14-NH2), respectively, following comparison of NMR

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• composition studies, A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991, Vavilova str. 28, Moscow, Russian Federation 10.3762/bjoc.18.148 Abstract A synthetic route to 1,4,6,10-tetraazaadamantanes (TAADs) bearing free and protected amino groups at the bridge N-atoms

• corresponding linear tris-oximes) and difficulties in the functionalization of N-hydroxy groups [21]. Currently, our research is focusing on TAAD derivatives bearing protected and free amino groups at the bridge nitrogen atoms (N-TAADs, Figure 1c). Our main interest in these products was due to their potential

• as synthetic receptors to form host–guest complexes based on H-bond interactions with amide/carbamoyl groups [31][32]. In addition, N-TAADs can be viewed as analogs of hexahydrazide ligands, which were reported to stabilize high-valent metal complexes [33][34]. Since N-amino groups can be easily

Amamistatins isolated from Nocardia altamirensis

• Till Steinmetz,
• Wolf Hiller and
• Markus Nett

Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40

• the end product of the pathway in N. altamirensis DSM 44997. Previous studies have demonstrated that, in nature, hydroxamates arise from the oxidation of terminal amino groups in amino acid side chains, followed by formylation or acylation of the resulting hydroxylamines. While the oxidations are

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• (Scheme 21). The product yield was significantly lower only by decreasing the reaction temperature. The amino groups present on the POP backbone enable a suitable electronic surrounding of the cobalt species which promotes the reaction. The catalyst showed excellent recyclability for 8 successive runs

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• used in organic synthesis, they are excellent analytical derivatization reagents to spectrophotometrically determine drugs containing primary and secondary amino groups. This review summarizes the literature involving β-NQS. Keywords: biological activities; derivatization reagents; β-NQS; organic

• drugs containing free primary and secondary amino groups [50][51]. As β-NQS is commercially available, it has become a widely used reagent for the chromogenic determination of pharmaceutical amines by spectrophotometry in pharmaceutical formulations [52]. This method, which uses a reagent to form a

• highlights some important drugs containing primary or secondary amino groups in capsules, tablets, powders, formulations, formulations of associated drugs, injection formulations, and biological fluids [42][58][59][60][61][62][63][64][65][66][67][68][69]. β-NQS reacts with aliphatic and aromatic amines

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• have been applied as fluorescence and electrochemical chemosensors [38][39][40][41][42][43][44][45]. Herein, we wish to report our endeavor in the facile synthesis of a new hemicucurbituril homologue, aminobenzene-containing hemicucurbituril 4 (Scheme 1). It was assumed that the amino groups could act