Synthesis and bioactivity of pyrrole-conjugated phosphopeptides

• Qiuxin Zhang,
• Weiyi Tan and
• Bing Xu

Beilstein J. Org. Chem. 2022, 18, 159–166, doi:10.3762/bjoc.18.17

• -phosphotyrosine, ʟ-phosphoserine, or ᴅ-phosphoserine, respectively. After being protected by an Fmoc group, these phosphorylated amino acids are suitable for solid-phase synthesis. We also used solution-phase synthesis to synthesize NBD-β-alanine according to the reported procedures [66]. We used standard Fmoc

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• analysis, 1H, 13C, and 15N NMR spectroscopy, HRMS, and single-crystal X-ray diffraction data. Keywords: β-enamino ketoesters; heterocyclic amino acids; 15N-labeled 1,2-oxazole; NMR (1H; 13C; 15N); 1,2-oxazole (isoxazole); X-ray structure analysis; Introduction 1,2-Oxazoles (isoxazoles) constitute an

• muscimol (I) and ibotenic acid (II) (Figure 1) have been isolated from several fungal species and are active on the γ-aminobutyric acid (GABA) and glutamate receptors of the central nervous system (CNS), respectively [8][9]. Various unnatural amino acids bearing a 1,2-oxazole moiety, such as

• nonproteinogenic α-amino acids, have been used as excitatory amino acid receptor agonists [10][11][12][13]. For example, (S)-AMPA (III) and (S)-ACPA (IV) are specific agonists of an AMPA receptor that mimic the effects of the neurotransmitter glutamate [14][15][16]. Unnatural heteroarene amino acids have also been

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• -oxabicyclo[5.2.1]decan-10-yl)carbamate was confirmed by X-ray diffraction. Keywords: aminocyclitol; azidolysis; bicyclic β-lactam; bicyclic lactone; cyclic β-amino acids; DFT; Introduction Cyclic β-amino acids have for the past few decades aroused widespread synthetic interest owing to their diverse

• biological activities, especially applications in the field of medicinal chemistry. β-Amino acids (i.e., amino acids containing an extra methylene group in the backbone) occur naturally in peptidic structures [1][2][3][4][5] and have been used in peptide design to obtain mixed peptides that retain their

• β-amino acid derivatives have antibiotic (oryzoxymycin) and antifungal activities (Figure 1) [12][13]. Among the cyclic β-amino acids, the most widely investigated derivatives are the five- and six-membered derivatives [8][9][10][14][15], but only a few synthetic methods are available for the

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

• with amino acids to be used as colorimetric indicators, Folin [45] developed a method based on naphthoquinone since there were records in the literature that indicated that naphthoquinones reacted with amines and proteins to form colored products. Among the tested o-naphthoquinones, he found that 1,2

• -naphthoquinone-4-sulfonic acid sodium salt (β-NQSNa, 18) was very effective as a colorimetric indicator of blood amino acids. This compound came to be called Folin's reagent. To achieve 18 with adequate purity to be used in the tests, an elaborate large-scale synthetic route was developed. β-Naphthol (20) was

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• natural product synthesis, pigments and dyes. Different variety of α-amino carbonyls [2], α-amino acids [3] and 1,2-diamines were prepared from the nitriles using homogeneous and heterogeneous catalysis [4][5][6]. One of the astonishing aspects of nitriles is that it can be easily converted to amines

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• peptide macrocyclisation of the two above mentioned side chain residues of the natural amino acids. However, these Pd-mediated stapling reactions were performed only on an analytical scale and the secondary structures of the cyclic peptides were not studied. Since tryptophan has only an incidence of about

• part in the destruction complex for β-catenin labelling in the canonical Wnt signalling. Loss-of-function mutations in this pathway lead to a dysregulated signal transduction causing cancer [75][76]. All-hydrocarbon stapled peptides comprising amino acids 467 to 481 of the axin CBD had been studied in

• the group of Verdine and evaluation of optimised staple positions at amino acids 471 (i) and 475 (i + 4) resulted in enhanced helicity and binding affinity to β-catenin, e.g., for peptide StAx-3 [77]. Following the StAx-3 peptide, we designed peptides including bromotryptophan in i-position and an

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• -sensitive Plasmodium falciparum. Herein, we describe the first total synthesis of hoshinoamide A by the combination of liquid-phase and solid-phase peptide synthesis. Liquid-phase synthesis is to improve the coupling yield of ʟ-Val3 and N-Me-ᴅ-Phe2. Connecting other amino acids efficiency and convergence is

• of the malaria parasites (IC50 = 0.96 μM) and African sleeping sickness (IC50 = 2.9 μM). Hoshinoamide C was firstly synthesized from Boc-protected amino acids in liquid phase [12]. Both hoshinoamides A and B are highly methylated polypeptides containing three N-methyl amino acids: N-Me-ʟ-Leu7, N-Me-ᴅ

• -Val5 and N-Me-ᴅ/ʟ-Phe2. Hoshinoamide C includes two N-methyl amino acids: N-Me-ᴅ-Phe2 and N-Me-ᴅ-IIe5. The C-terminal Pro is functionalized as methyl ester, while the N-terminal polypeptide is linked to the long alkyl chain amino acid Aha8/Ana8/Ama7 and p-hydroxybenzoic acid Hba9/Hba8. Hoshinoamides

Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

• Tanmoy Halder and
• Somnath Yadav

Beilstein J. Org. Chem. 2021, 17, 2915–2921, doi:10.3762/bjoc.17.199

• for further conjugation to other moieties towards the synthesis of vaccine conjugates by removal of the anomeric PMP group. This has been previously demonstrated by removal of the anomeric PMP group, conversion to a glycosidic donor, and further conjugation to either linkers or amino acids by several

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• derivatives. It was perceived that the MDO self-assembled in situ from amino acids and cinchona alkaloid derivatives. For example, on reacting (E)-2-[2-(3-aryl-3-oxoprop-1-en-1-yl)phenyl]acetaldehydes 21 with ethyl or benzyl (E)-2-[(4-methoxyphenyl)imino]acetates 22 in the presence of the MDO 23/24

• addition in conjunction with one or more reactions leading to overall very high yields and ee are noteworthy. Another strategy of interest appears to be the generation of organocatalysts of enhanced efficacy in situ by mixing squaramides with amino acids again giving >99% ee. It may be perceived that in

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• part of their mechanism. Ketol-acid reductoisomerase (KAR), which is involved in the biosynthesis of branched-chain amino acids, takes as its substrate either (2S)-acetolactate (60, R = Me), which is ultimately converted into valine or leucine, or (2S)-acetohydroxybutyrate (60, R = Et), which

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• quinolones 56, indolo[3,2-c]quinolines 57, β-amino acids 58, and 1,4-dihydropyridine derivatives 59 were obtained through this route in moderate yields (Scheme 26). Besides nucleophiles, aromatic amines also reacted with redox-active radical precursors, such as NHPI [95] and N-alkoxyphthalimides 55 [96]. The

Synthesis of new substituted 7,12-dihydro-6,12-methanodibenzo[c,f]azocine-5-carboxylic acids containing a tetracyclic tetrahydroisoquinoline core structure

• Agnieszka Grajewska,
• Maria Chrzanowska and
• Wiktoria Adamska

Beilstein J. Org. Chem. 2021, 17, 2511–2519, doi:10.3762/bjoc.17.168

• , several acids have been prepared in satisfactory yields. An unprecedented chemical behavior of a Petasis reaction product in diluted HCl solution leading to the formation of a phenylglycine derivative has been observed and the mechanism explaining such reactivity has been proposed. Keywords: amino acids

• Petasis three-component reaction followed by the Pomeranz–Fritsch–Bobbitt cyclization. The Petasis reaction between boronic acids, carbonyl derivatives, and amines, leading to the formation of amino acids and the Pomeranz–Fritsch–Bobbitt cyclization of amino acetals, leading to the construction of C-1

• 5a–d carried out in DCM at rt for 24 h to afford amino acids 6a–g (Scheme 4). The condensation of N-(2,3-dimethoxybenzyl)aminoacetaldehyde acetal (3a) with glyoxylic acid hydrate (4) and 3,4-dimethoxyphenylboronic acid (5a) afforded the Petasis reaction product 6a in a high 94% yield. The double

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• addition of 1 M HCl (20 µL), diluted with acetonitrile (100 µL), and filtered through a PTFE membrane filter (0.45 µm). The standard amino acids (ᴅ-Thr, ʟ-Thr, and ʟ-allo-Thr) were subjected to derivatization with ʟ-FDAA by using the same method previously described. For the HPLC analysis, mixtures of the

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• of natural products (especially macrocycles) [12], alkaloids [13], amino acids and functionalized biomolecules such as peptides [14][15][16][17][18][19][20] or various drugs [21]. Due to the ring strain, bicyclic systems and derivatives, such as norbornadiene derivatives can easily be converted

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• the late-stage modification of amino acids and peptides in 2016 (Scheme 27A and B) [159]. The methodology facilitated the targeted C–H oxidative modifications in amino acids and peptides concomitant with the preservation of the α-center chirality in good yields and broad scope regarding the number of

• amino acids and peptide scaffolds compatible with the transformation. The late-stage oxidation of proline 76 to 5-hydroxyproline furnished interesting intermediates, giving access to relevant motifs in peptide chemistry (Scheme 27C). Sesquiterpenes are known to present complex polycyclic structures with

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• discussed. Amino acids and cationic modifications that replace the core structure of the nucleobase, sugar, or the internucleotide linkage have been excluded. Cationic amine-functionalized group substitutions at nucleobases One strategy that has attracted a lot of interest is the attachment of cationic

• relative to the downregulation of the reference ASO (Oblimersen) [91]. In an entirely different approach, the 2’-amino group of amino-LNA-thymine (amino-LNA-T) has been explored as an attachment point for various cationic groups. As one example, amino acids such as glycine, lysine, and proline in different

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• positions of the backbone α-Modified PNA: Adding substituents to the N-(2-aminoethyl)glycine backbone has been an obvious starting point for PNA modification. Nielsen and co-workers were the first to replace the glycine residues in PNA backbone with various chiral amino acids [67][68]. Most of these α

• -modified PNA monomers (Figure 5) slightly reduced PNA binding affinity, with ᴅ-amino acids being somewhat better accommodated in the backbone than ʟ-amino acids and ᴅ-Lys being the only α-backbone modification that slightly increased PNA’s binding affinity to complementary DNA (but not RNA) [67]. Circular

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• employing a variety of amino esters and a wide range of (hetero)aromatic and alkyl ketones. Natural products, such as 5α-cholestan-3-one and dihydrotestosterone, were also tolerated, affording a new strategy to modify biologically active compounds. Amino acids, such as tyrosine, ʟ-Phe-ʟ-Phe, glutamic acid

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• important tool in the asymmetric synthesis of aziridines [25][26], α-amino acids [27][28], β-amino acids [23][29] and branched α-amines [30][31]. The Darzens-type asymmetric synthesis of N-(p-toluenesulfinyl)aziridine 2-carboxylate esters (7 and 8) was described through the addition of lithium α

• hand, natural amino acids proline and hydroxyproline are functionalized pyrrolidines that have found great application in organic synthesis as chiral organocatalysts in stereoselective processes [93][94]. Cyclizations involving a position in the starting chiral imine Arylation of chiral sulfinyl imines

• ) [105]. Li and Xu reported a method for the enantioselective synthesis of β,γ-unsaturated α-amino acids 100, by a Lewis acid-promoted diastereoselective Petasis reaction of vinylboronic acids 98, (R)-N-tert-butanesulfinamide and glyoxylic acid (99). They found that the best results were obtained working

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• Vaillancourt et al. in 2001 for the synthesis of different monosubstituted biguanides with potential antidiabetic properties (Scheme 34) [71]. In particular, the condensation of this reagent with different amino acids such as β-alanine, 3-aminopropionic acid, and taurine in the presence of trimethylamine in

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• transferrin receptor is highly expressed in brain capillaries, nucleated cells, and in rapidly dividing cells [21], and its endogenous ligand transferrin has previously been used to increase transport of small molecules and oligonucleotides across the BBB [21][22][23]. The peptide T7 consisting of seven amino

• acids (H-HAIYPRH-NH2) was identified via phage display [24] and has a high affinity (≈10 nM) for the transferrin receptor [24][25]. This peptide does not compete with endogenous transferrin binding and has been used to successfully enhance drug delivery to brain tissue [15][22][24][25][26]. Both

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• % along with drastic reduction in side product formation and reaction time from 24 h to 50 min when compared to the conventional method. The method proved to be efficient even with chiral amino acids resulting in separable diastereomeric mixtures. The synthesized molecules manifested potent anti

• co-workers [50] demonstrated an aqueous phase, diastereoselective, multicomponent reaction involving substituted isatins 35, β-nitrostyrene 36 and benzylamine (20) or α-amino acids 37 using microwave irradiation to afford a library of spirooxindoles 38 in good yields under catalyst-free conditions

• acids 37. Likewise, the four-component reaction comprised of isatin 35, but-2-ynedioates 39, amino acids 37 and phenacyl bromides 41 to yield the N-acylated spirooxindoles 42 in good yields (Scheme 13). The reaction effectively explored the 1,3 dipolar compound generated with isatin and amino acids

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• synthesis of unnatural α-amino acids 129 and precise alkylation modification of peptides in the later stage (Scheme 45). Even in the presence of other amino acid residues, this protocol has excellent regio- and chemoselectivity, providing a sequence of novel corresponding dipeptides with good yield. The

• construction of C–S bonds C–S bonds are commonly present in amino acids, proteins, glycosides, nucleic acids, and other biological macromolecules. In recent years, photocatalyst- and transition-metal strategies have been employed to construct C–S bonds [66][67][68][69]. The C–S bond synthesis via EDA-complex

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• was stepwisely elongated, and eventually conjugated with the (perfluoroalkyl)ethyl acids (Scheme 2). After the cleavage from the resin, the Fmoc groups of the amino acids were removed, and the F-lipopeptides were purified using a dialysis membrane. According to mass spectrometry, FTIR, and HPLC

• fluorine–fluorine interactions. Experimental Materials. We purchased Fmoc-protected amino acids, N,N-dimethylformamide (DMF), dichloromethane (DCM), methanol, 1-hydroxybenzotriazole (HOBT), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU), N,N-diisopropylethylamine (DIPEA

• for capping the unreacted amino acids and the mixture was shaken for 5 min. In a similar manner, each of the peptide chains was elongated by coupling Fmoc-Ser(t-Bu)-OH (3 equiv), Fmoc-Gly-OH (3 equiv) and Fmoc-Lys(Boc)-OH (3 equiv) to the Rink Amide AM resin. After introducing Fmoc-Lys(Fmoc)-OH as the

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• dichlorophosphites followed by alcoholysis with hydroxy esters, the phosphinylation of hydroxy esters with phosphonochloridites followed by oxidation, and the carbene insertion of N-protected amino acids with 1-diazoalkylphosphonates. This review includes the synthesis of α-, β-, and γ-phosphonodepsipeptides and

• transpeptidase, which catalyzes the transfer of the γ-glutamyl group of glutathione and related γ-glutamyl amides to amino acids and peptides (transpeptidation) or to water (hydrolysis). For this purpose, N-Cbz-aminophosphonic acid 91 was first transformed to the corresponding dichloride 92, which underwent a

• prepared from optically pure amino acids and converted to the benzyl or methyl [2-hydroxyalkanoyl]glycinates 97. Following the similar strategy, phosphonodepsitripeptides 99 and 102 were synthesized. The phosphonodepsidipeptide 104 was prepared through the sequential coupling of N-Cbz-γ