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

• triethylsilane in TFA-CH3Cl, resulting in the N-methylated amino acid as the final product [38]. The third method for chemical N-methylation involves the use of protection groups that also enhance the reactivity of the primary amine (Figure 2). Once the amine is deprotonated, an electrophilic methylation reagent

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• studies developed by Naturale’s group, α-, β-, and γ-amino acids of linear and branched chains were used, as well as different amine protection groups (Table 5). The results revealed that the functionalization of naphthoquinones by a radical addition of decarboxylated α-, β- and γ-N-protected amino acids

Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole

• Estelle Silm,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2022, 18, 167–173, doi:10.3762/bjoc.18.18

• -protecting group and electron-withdrawing properties of the protection groups are essential for coordination with the catalyst and for the reactivity of the Michael acceptor. Using a tosyl-protected oxindole the reaction was sluggish, the yield was low and the enantioselectivity could not be determined

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

• (Supporting Information File 1), and the protection groups in them meet criterion (2). In the case of 3h, the compound was consumed under the Williamson ether formation conditions indicating that the 3-(dimethylamino)-3-oxopropyl group in it does not meet criterion (2). Based on the results of screening

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• -iodophenylazo)-4-chloropyridine (17) with LiSSiMe3 (8) [28], t-BuSH (13) and HSCH2CH2CO2CH3 (15) [29]. Electron-deficient aromatic, silylated thiols exhibit very labile Si–S bonds [30]. Thus, even bulky silyl protection groups are not suitable as protecting groups for the subsequent Suzuki reaction

• porphyrin 22 and the disulfide 12, obviously because of catalyst poisoning by sulfur [32][33]. To circumvent these problems, protection groups were introduced. Protection with methyl 3-mercaptopropionate (15) [29] was successful, however, inhibition of the Suzuki reaction was observed. We assume an alkaline

A dynamic combinatorial library for biomimetic recognition of dipeptides in water

• Florian Klepel and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2020, 16, 1588–1595, doi:10.3762/bjoc.16.131

• conclusively to test for binding behavior and selectivity, both isomers a(CFC)2 and p(CFC)2 were synthesized using a suitable protecting group strategy (Scheme 2b). One of the Trt protection groups was replaced by an acetamidomethyl (Acm) group (CFC(Acm)), which is stable under the cleaving conditions of the

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• prevented not only the installation of protection groups at the C-2 and C-7 position, but also circumvented the tedious purification of anomeric isomers, as this gave only the α-isomer. Besides, the configuration of the alcohol OH-4 and the NHAc group in position C-5 changed from equatorial to axial after

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

• the overall results of the deprotection and cleavage procedure. Removal of the oxidized dM-Dmoc protection groups and cleavage of the oxidized Dmoc linker were achieved with a solution of the weak non-nucleophilic base potassium carbonate at pH 8 at room temperature giving the fully deprotected 5

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

Synthesis of functionalised β-keto amides by aminoacylation/domino fragmentation of β-enamino amides

• Pavel Yanev and
• Plamen Angelov

Beilstein J. Org. Chem. 2018, 14, 2602–2606, doi:10.3762/bjoc.14.238

• process was slower and could be effectively avoided by limiting the deprotection time to 5 min in neat TFA. In this way a series of ω-amino-β-keto amides 11 with variable chain lengths and N-protection groups was successfully obtained (Scheme 6, Table 2). Minor amounts of the enol tautomer (1–10%) were

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• is incompatible with the standard deprotection treatment under basic conditions (generally aqueous ammonia) used to cleave other common base-labile acyl protection groups from nucleobases and release ON from the solid support. Furthermore, as the aqueous solubility of fully modified SATE

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• analogues The development of synthesis methods of nucleobase analogues remains a challenge. This is mainly due to the presence of multiple reactive functional groups both on the nucleobase as well as the sugar moiety and requires the introduction of orthogonal protection groups. A careful consideration of

• protection groups is paramount as an extensive use adds additional steps as well as complexity to the synthesis. The design and synthesis of fluorescent nucleobase analogues (FBAs) add on additional challenges such as obtaining features that introduce useful photophysical properties, for example, extended

• synthesis of tCnitro followed the procedure of Roth et al. [39] to furnish the aromatic core 13 (Scheme 3). Compound 13 was then glycosylated by making the sodium salt and reacting it with Hoffer´s α-chloro sugar yielding 14 in 11% yield after isolation [46]. The p-toluoyl protection groups were cleaved by

Facile synthesis of a 3-deazaadenosine phosphoramidite for RNA solid-phase synthesis

• Elisabeth Mairhofer,
• Elisabeth Fuchs and
• Ronald Micura

Beilstein J. Org. Chem. 2016, 12, 2556–2562, doi:10.3762/bjoc.12.250

• -amino-3-deazapurine and benzoyl-protected 1-O-acetylribose. The novel path is superior to previously described syntheses in terms of efficacy and ease of laboratory handling. Keywords: deazapurine nucleoside; nucleosidation; protection groups; ribozymes; Introduction The synthesis of 3-deazaadenosine

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• -1,2-cyclohexandiamine was the ligand of choice in combination with potassium carbonate as base. In our case, the usage of Boc and Teoc protection groups in the cross-coupling reaction gave the best results. By using the optimized reaction conditions the dehydroisoleucine peptide was synthesized

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

• and in some cases, the repetitive TFA acidolysis for Boc deprotection could have an impact on sensitive peptide bonds and acid-catalyzed side reactions [39]. And, since it is no orthogonal strategy, the Bn removal always leads to Boc deprotection. A tremendous diversity of side-chain protection groups

A new building block for DNA network formation by self-assembly and polymerase chain reaction

• Holger Bußkamp,
• Sascha Keller,
• Marta Robotta,
• Malte Drescher and
• Andreas Marx

Beilstein J. Org. Chem. 2014, 10, 1037–1046, doi:10.3762/bjoc.10.104

• 4 [42] yielding 5 in acceptable yields (Scheme 1). Finally, compound 5 was transformed into 6 by phosphitylation resulting in a building block that bears protection groups and reactive groups that are standard in solid phase DNA oligonucleotide synthesis. Synthesis of branched oligonucleotides. DNA

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• polyketide-derived thioesters suited for biosynthesis studies. Keywords: aldol reaction; coenzyme A; natural products; pig liver esterase; polyketide biosynthesis; protection groups; Introduction Borrelidin (1) is a macrolactone polyketide natural product with promising antibacterial, antimalarial

• 17a and 17b with HSNAc and triethylamine in DMF, they underwent clean transesterification furnishing SNAc thioesters 18a and 18b in 70% combined yield [20] (Scheme 3). With the mixture of 18a and 18b in hand, we turned to the mild removal of the protection groups. For TBS cleavage, we focused on

• respective methyl ester ylide 26 [25][26]. The reaction of phosphorane 24 with 11 under neutral conditions at 50 °C gave the desired diene 9a in very good 88% yield and in nearly perfect E-selectivity. The protection groups were removed from 9a under the previously established conditions to finally give

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• , isobutyroyl or pivaloyl protection groups [21][22][23]. Alternatively, the use of bromo-derivative 10 (Scheme 2), which is easily synthesised in two steps from glucuronolactone [14][24] has been shown to glucuronidate primary and secondary alcohols under Koenigs–Knorr conditions [7][8][25][26]. Due to the

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• ; cyclic β-tripeptide scaffold; orthogonal protection groups; peptide synthesis; template-assembled synthetic proteins (TASP); Introduction Cyclic β-tripeptides form structurally well-defined secondary structures with the potential for alignment of the rings to form intermolecular aggregates [1]. Due to

• functionalization by amide bond formation. To protect the lysine side chain for selective and orthogonal amide-bond formation following the solid-phase peptide synthesis (SPPS), the protection groups fluorenylmethoxycarbonyl (Fmoc) and carbobenzyloxy (Cbz) were applied. Alteration of the amine in the third β

Investigation of the network of preferred interactions in an artificial coiled-coil association using the peptide array technique

• Raheleh Rezaei Araghi,
• Carsten C. Mahrenholz,
• Rudolf Volkmer and
• Beate Koksch

Beilstein J. Org. Chem. 2012, 8, 640–649, doi:10.3762/bjoc.8.71

• acid-labile protection groups of the amino acid side chains were cleaved by using 90% trifluoro-acetic acid (TFA) for 30 min and 60% TFA for 3 h. To ensure adequate quality, the peptides to be analyzed were cleaved from the membrane by using the standard protocol as described by Wenschuh et al. [15

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• protection groups at the sugar ring were removed by the reaction with TBAF. Finally, the 5'-hydroxyl groups were tritylated and the 3'-hydroxy group converted to the corresponding phosphoramidite 150. The resulting phosphoramidite was incorporated into a 12-mer oligodeoxynucleotide via automated solid-phase