Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• -responsive photo-labile protecting group [56][57][58] with simple cyclic stilbene structures such as 2-(4-nitrophenyl)benzofuran (NPBF) that absorb in the NIR region of 710–760 nm for the uncaging of bioactive substances such as glutamate and Ca2+ [59][60][61][62][63][64]. Herein, we report the synthesis of

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• pool; glutamate analogues; Introduction L-Glutamic acid (1, Figure 1) plays an important role in the biosynthesis of purine and pyrimidine nucleobases [1]. It also takes part in metabolic transformation to L-glutamine by L-glutamate synthetase (GS) which is crucial for cell maintenance. In neoplastic

• ]. Several derivatives of L-glutamic acid functioning as anticancer agents have been reported [4]. But primarily L-glutamic acid is known as the major excitatory neurotransmitter in central nervous system which acts by binding to glutamate receptors [5][6][7]. However, these interactions are linked to

• additional substituents, tuning the conformational flexibility of analogues and introducing groups capable of hydrogen bonding. Crystallographic data obtained for glutamate receptors [13][14][15] showed complex set of atoms interacting electrostatically and through hydrogen bonds and the conclusions from

Volatiles from three genome sequenced fungi from the genus Aspergillus

• Jeroen S. Dickschat,
• Ersin Celik and
• Nelson L. Brock

Beilstein J. Org. Chem. 2018, 14, 900–910, doi:10.3762/bjoc.14.77

• motif that is typical for class II TSs (312DADD) and the C-terminal domain exhibits an aspartate-rich motif DDXXD, in this case with two of the usually found asparate residues exchanged by glutamate, and an NSE triad, a motif with highly conserved Asn, Ser and Glu residues, for Mg2+ binding as in class

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• most used enzymes for the cofactor regeneration are glucose dehydrogenase (glucose to glucuronic acid), lactate dehydrogenase (pyruvate to lactate), glutamate dehydrogenase (α-ketoglutarate to glutamate) and formate dehydrogenase (formate to CO2). In particular, the last enzyme is interesting because

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (SN1) or associative (SN2) pathway. [2H]-Isotopomer ratios in the reactions were assayed using the Courtieu 2H NMR method in a chiral liquid crystal (poly-γ-benzyl-L-glutamate) matrix and

• with the electric field gradients associated with the orientated media, creating anisotropy and resolving into two sets of doublets. If there is sufficient resolution between these quadrupolar couplings, then the enantiomeric ratio can be recorded. We have used poly-γ-benzyl-L-glutamate (PBLG

What contributes to an effective mannose recognition domain?

• Christoph P. Sager,
• Deniz Eriş,
• Martin Smieško,
• Rachel Hevey and
• Beat Ernst

Beilstein J. Org. Chem. 2017, 13, 2584–2595, doi:10.3762/bjoc.13.255

• ) exhibits a desolvation energy of 89.6 kJ/mol due to the additional interactions to a glutamate and w2. On the other hand, w1 in the exact same binding site is the least costly among the three waters, as it forms fewer interactions and its loss can also be partially compensated by w2 (Figure 5B). Profiling

• for the formation of a homodimer of A (Figure 8B) [40]. It is believed that this dimer enables transport of the lectin from the Golgi apparatus to cell membranes [73]. Due to a dislocated glutamate in the side chain of the homodimer (Figure 8B), the affinity for calcium binding and therefore also

• /day [81]. Calcium-dependent lectins require a non-acidic environment, such as found in blood, since at lower pH the glutamate and/or aspartate side chains essential for calcium binding can become partially protonated. Instead, FimHLD forms an extensive hydrogen-bond network in a buried, rigid binding

Herpetopanone, a diterpene from Herpetosiphon aurantiacus discovered by isotope labeling

• Xinli Pan,
• Nicole Domin,
• Sebastian Schieferdecker,
• Hirokazu Kage,
• Martin Roth and
• Markus Nett

Beilstein J. Org. Chem. 2017, 13, 2458–2465, doi:10.3762/bjoc.13.242

• was obtained from the German Collection of Microorganisms and Cell Cultures (DSMZ). The bacterium was routinely cultured at 30 °C in CY (casitone 3 g/L, yeast extract 1 g/L, CaCl2·2 H2O 1 g/L, pH 6.8) or VNY liquid medium (sodium glutamate 10 g/L, yeast extract 2 g/L, MgSO4·7 H2O 2 g/L, NaH2PO4 0.10 g

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• phosphonic-carboxylic acid 93 [216] or the cyclopropylphosphonic acid 94 that was assessed as inhibitor of the glutamate metabotropic receptors [217]. The synthesis of phosphonic acid via phosphonodiamide intermediates started by the use of the nucleophilic bis(dialkylamino)chlorophosphine. This possibility

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• retention of configuration (Figure 5) as first described by Koshland [53]. However, in the case of GHs, the mechanism generally implies the intervention of two amino acid side chains, typically glutamate or aspartate, and goes through oxocarbenium ion-like transition states. Inverting GHs operate via a

Continuous-flow synthesis of highly functionalized imidazo-oxadiazoles facilitated by microfluidic extraction

• Ananda Herath and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2017, 13, 239–246, doi:10.3762/bjoc.13.26

• sphingosine-1-phosphate 1 (S1P1) receptor agonists [25][26][27] and metabotropic glutamate subtype 5 (mGlu5) receptor negative allosteric modulators (NAMs) [25][28][29][30]. Most synthetic efforts toward the preparation of these heterocyclic systems utilize a multistep, in-flask approach as illustrated by the

Inhibition of peptide aggregation by means of enzymatic phosphorylation

• Kristin Folmert,
• Malgorzata Broncel,
• Hans v. Berlepsch,
• Christopher H. Ullrich,
• Mary-Ann Siegert and
• Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

• intramolecular Coulombic repulsions between negatively charged glutamate residues and the phosphate, or in electrostatic pairing with positively charged lysine or arginine residues, resulting in the perturbation of higher ordered secondary structures [53]. The impact of electrostatics on peptide and protein

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• by Sakai et al. together with the already known and closely related dysiherbaine [42]. Neodysiherbaine A (14) is a neurologically active compound that acts as a glutamate receptor agonist and shows epileptogenic properties. Contiguous to the isolation, the first synthesis has been carried out by the

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• precursor peptide NisA showed that dehydration involves the glutamylation of Ser and Thr side chains prior to elimination of glutamate [50]. This mechanistic proposal was established due to the observation that three NisB mutants (R786A, R826A and H961A) were able to transfer multiple glutamates to NisA

• biochemical and structural work identified that glutamate is supplied by glutamyl-tRNA, and that glutamylation and elimination steps are catalysed by distinct domains within NisB [52]. Protein homology analysis indicated that LanB-like proteins are widespread in bacteria [52], so this unusual use of an

• knotted structures, where a tail peptide is threaded through a macrolactam that is formed by the condensation of the N-terminal amino group with an asparatate or glutamate side-chain carboxylate. These are highly stable structures, and lasso peptides with a variety of biological activities have been

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• phosphonic analogues of phenylglycine, exhibited their herbicidal activity [10], and are used as plant growth regulators [10], agrochemical fungicides [11][12] and glutamate receptor modulators [13]. It is therefore expectable that C-pyrene derivatives may have similar or even more promising biological

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• of PpyS, docking studies of the substrates onto the catalytic cysteine were performed. The resulting model suggested that a glutamate residue, which reaches into the catalytic cavity of the respectively other homodimer, acts as a base by forming a hydrogen bond with the α-carbon of the covalently

• bound substrate (Figure 25). Indeed, the exchange of this glutamate against an alanine residue resulted in an inactive version of the protein. Further an arginine residue, which could be involved in dimerization, was mutated to an aspartate. Also this mutant lost its catalytic activity, indicating that

• to fuse two ketoacyl moieties, as exemplified by CorB and MxnB. Another mechanism is the fusion of one ketoacyl moiety with one acyl moiety, as shown for PpyS-like KSs. All evolved from FabH-type KSs, but form different clades in phylogenetic analyses. PpyS-like enzymes show the conserved glutamate

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• the reaction of 256 with catalyst 5 in the presence of vinyl acetate (258) (Scheme 53). The RRM approach is useful to design diverse analogs of the marine toxin dysiherbaine, which displays antagonistic activity on ionotropic glutamate receptors from oxanorbornenes [54]. The report reveals the

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

• Mahesh K. Lakshman,
• Manish K. Singh,
• Mukesh Kumar,
• Raghu Ram Chamala,
• Vijayender R. Yedulla,
• Domenick Wagner,
• Evan Leung,
• Lijia Yang,
• Asha Matin and
• Sadia Ahmad

Beilstein J. Org. Chem. 2014, 10, 1919–1932, doi:10.3762/bjoc.10.200

• reported to be promising entities in the treatment of glutamate mGluR2 receptor dysfunction-related diseases, such as neurological and psychological disorders [11]. Benzotriazole-derived compounds also have applications in materials chemistry. For example, 5-alkyl- and 5-alkanoylaminobenzotriazoles have

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• various types of bioactivity, e.g., herbicidal [12], inhibition of cell growth and enzyme activity [13][14][15][16][17][18], inhibition of voltage-gated sodium channels [19] and metabotropic glutamate receptor-5a (hmGluR5a) [20]. Consequently, our second aim was to extend the reaction to the preparation

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• confirming the proposed stereochemistry [49]. Glutamate metabotropic receptor agonists (2000, 2007) The metabotropic glutamate receptors (mGluRs) are members of the vast family of G-protein coupled receptors which are expressed throughout the central nervous system. They consist of at least eight sub-types

• , which are divided into three groups I–III. Through binding of glutamate 161 (Figure 9), the most abundant excitatory neurotransmitter in the mammalian central nervous system, the mGluRs are activiated and participate in the regulation of synaptic transmission and neuronal excitability through a

Automated solid-phase peptide synthesis to obtain therapeutic peptides

• Veronika Mäde,
• Sylvia Els-Heindl and
• Annette G. Beck-Sickinger

Beilstein J. Org. Chem. 2014, 10, 1197–1212, doi:10.3762/bjoc.10.118

• . Orthogonal deprotection of Dde enabled coupling of a glutamate spacer and the desired fatty acid (Figure 5) by amide-bond formation [99]. Synthesis of PEGylated conjugates (Figure 5) occurred on solid phase (for 2 kDa PEG) according to the same procedure. For PEGylation with a much larger group (20 kDa PEG

Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally “frozen” analogues of L-glutamic acid

• Beatrice Bechi,
• David Amantini,
• Cristina Tintori,
• Maurizio Botta and
• Romano di Fabio

Beilstein J. Org. Chem. 2014, 10, 1114–1120, doi:10.3762/bjoc.10.110

• the identification of new potent and selective ligands of ionotropic and metabotropic glutamate receptors (GluRs). To this aim, bicycle compound Ib was designed and synthesised from D-serine as novel [2.3]-spiro analogue of L-Glu. This frozen amino acid derivative was designed to further limit the

• coupled or metabotropic glutamate receptors (mGluRs) [6][7]. To date, eight different metabotropic receptor subtypes (mGluR1–8) have been identified. Compounds that modulate the function of the mGluRs might be useful for treating a wide range of CNS disorders including schizophrenia, depression, anxiety

• (3) [11] and MGS0028 (4) [12][13]. In addition, the conformationally constrained analogues of L-Glu 6a,b, 7, 8 and 9a,b were reported [14][15][16][17][18] as either ionotropic or metabotropic glutamate receptors ligands, obtained by “freezing” the glutamate skeleton in search for subtype selective

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

Synthesis and characterization of novel bioactive 1,2,4-oxadiazole natural product analogs bearing the N-phenylmaleimide and N-phenylsuccinimide moieties

• Catalin V. Maftei,
• Elena Fodor,
• Peter G. Jones,
• M. Heiko Franz,
• Gerhard Kelter,
• Heiner Fiebig and
• Ion Neda

Beilstein J. Org. Chem. 2013, 9, 2202–2215, doi:10.3762/bjoc.9.259

• oxadiazole core is quisqualic acid (Figure 1). This metabolite was obtained from the seeds of Quisqualis indica and Q. fructus [5][6] and is a strong agonist for AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors and group I metabotropic glutamate receptors [7]. Furthermore, 1,2,4

Synthesis of the calcilytic ligand NPS 2143

• Henrik Johansson,
• Thomas Cailly,
• Alex Rojas Bie Thomsen,
• Hans Bräuner-Osborne and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 1383–1387, doi:10.3762/bjoc.9.154

• major classes (A, B and C) of which the rhodopsin-like class A is the largest and most diverse, and which has been well-studied and subject to drug targeting [3]. GPCR class C is much smaller and comprises only 22 known receptors including eight metabotropic glutamate (mGlu) receptors, two γ