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Search for "activation" in Full Text gives 1129 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

  • Zining Li,
  • Sana Jindani,
  • Volga Kojasoy,
  • Teresa Ortega,
  • Erin M. Marshall,
  • Khalil A. Abboud,
  • Sandra Loesgen,
  • Dean J. Tantillo and
  • Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

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  • prior chair-to-boat conformational change of 9.7 kcal mol−1, providing a similar activation barrier for the Cope rearrangement step itself (27.2 kcal mol−1). For 1, a potential Cope rearrangement was predicted to be 32.5 kcal mol−1, an overall higher energetic barrier compared to 2 (Figure S11
  • activation energy may allow for oxy-Cope rearrangement at 28 °C. DFT calculations (in toluene) of 5-hydroxyalbireticulene for both the pseudo-axial and pseudo-equatorial conformations of the C5 hydroxy moiety suggest that there is not a significant difference in the free energy barriers for the oxy-Cope
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Published 07 Jun 2024

Phenotellurazine redox catalysts: elements of design for radical cross-dehydrogenative coupling reactions

  • Alina Paffen,
  • Christopher Cremer and
  • Frederic W. Patureau

Beilstein J. Org. Chem. 2024, 20, 1292–1297, doi:10.3762/bjoc.20.112

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  • substitution patterns on the redox catalytic activity. Keywords: cross-dehydrogenative coupling; O2 activation; phenotellurazine; redox catalysis; Te catalysis; Introduction Tellurium catalysis has become increasingly important in recent years. This is due to its unique chalcogen bonding ability, thus
  • enabling the activation of small yet highly relevant organic substrates. For example, Huber and co-authors recently designed a Te-based catalyst in an indole Michael addition reaction [1][2][3][4][5]. Pale and Mamane utilized another Te-based catalyst in an electrophilic bromine-mediated cyclization
  • reaction [6][7], and Gabbaï yet another in a different cyclization reaction [8][9], among other catalytic chalcogen bonding activation examples [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. In contrast, we have reported recently some redox-active Te-based catalysts
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Published 04 Jun 2024

Domino reactions of chromones with activated carbonyl compounds

  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

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  • undergo cyclization reactions under mild conditions. In case of 1,3-diphenylacetone (4a) some activation of the methylene group is observed as well, because of benzylic stabilization. Dianions of 1,3-dicarbonyl compounds follow a different regioselectivity as compared to simple monoanions [6][7][8][9][10
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Published 29 May 2024

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

  • Johannes Rocker,
  • Till J. B. Zähringer,
  • Matthias Schmitz,
  • Till Opatz and
  • Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

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  • catalyst in the sulfonylation/arylation of styrenes and as a triplet sensitizer in energy transfer catalysis. The singlet lifetime is sufficiently long to exploit the exceptional excited state reduction potential for the activation of 4-cyanopyridine. Photoinduced electron transfer generating the radical
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Published 28 May 2024

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

  • Jinmin Gao,
  • Liyuan Li,
  • Shijie Shen,
  • Guomin Ai,
  • Bin Wang,
  • Fang Guo,
  • Tongjian Yang,
  • Hui Han,
  • Zhengren Xu,
  • Guohui Pan and
  • Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

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  • conditions [25]. This observation not only affirmed 8 as an intermediate in jadomycin biosynthesis but also suggested a role as a more electron-rich substrate with the potential for direct activation of molecular oxygen. We first confirmed the generation of 8 in the biosynthetic pathway of kinamycin. The
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Published 23 May 2024

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

  • Mohd Farhan Ansari,
  • Atul Kumar Maurya,
  • Abhishek Kumar and
  • Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

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Published 21 May 2024

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

  • Maksim V. Kvach,
  • Stefan Harjes,
  • Harikrishnan M. Kurup,
  • Geoffrey B. Jameson,
  • Elena Harjes and
  • Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

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  • activation-induced deaminase (AID) and APOBEC3 (A3), act preferentially on single-stranded DNA (ssDNA) containing one or multiple cytosine residues. Although some action was detected on RNA, none was observed on cytidine or cytosine alone. Each cytosine or cytidine deaminase has an important biological
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Published 15 May 2024

Light on the sustainable preparation of aryl-cored dibromides

  • Fabrizio Roncaglia,
  • Alberto Ughetti,
  • Nicola Porcelli,
  • Biagio Anderlini,
  • Andrea Severini and
  • Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

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  • be employed in two variants modulated by light irradiation. This external switch can be used to selectively trigger side-chain or core halogenation. Keywords: aryl halides; benzyl halides; bromination; sustainability; Introduction Activation through halogens has become a key strategy in achieving
  • context of covalent organic frameworks (COFs) and metal-organic frameworks (MOFs), frequently assembled through imine linkages. While C–H activation through halogens presents clear technical advantages, it also brings forth concerns about the toxicity of halo compounds to both human health and the
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Published 14 May 2024

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

  • Akanksha Ashok Sangolkar,
  • Rama Krishna Kadiyam and
  • Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

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  • photoswitching cycle. The activation energy required to trigger the transformation of the metastable photoisomer to the parent diene is called the thermal back isomerization barrier. The TBR barrier governs the duration of storage of harvested solar energy in the MOST devices. Photoswitching systems exhibiting a
  • DFT-based PBE method is still better to predict the geometry of TS using nudged elastic band (NEB) calculations and multireference methods determines the activation energy values close to the experiments [42]. In the present investigation, the geometry of all the TS structures was obtained with the
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Published 13 May 2024

Novel analogues of a nonnucleoside SARS-CoV-2 RdRp inhibitor as potential antivirotics

  • Luca Julianna Tóth,
  • Kateřina Krejčová,
  • Milan Dejmek,
  • Eva Žilecká,
  • Blanka Klepetářová,
  • Lenka Poštová Slavětínská,
  • Evžen Bouřa and
  • Radim Nencka

Beilstein J. Org. Chem. 2024, 20, 1029–1036, doi:10.3762/bjoc.20.91

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  • the replication by acting as a delayed chain terminator or by causing genetic corruption in the viral RNA and includes the first FDA-approved antiviral drugs in the therapy of COVID-19 patients, remdesivir [10] and molnupiravir [11]. The usability of NAIs may largely depend on the metabolic activation
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Published 06 May 2024

Carbonylative synthesis and functionalization of indoles

  • Alex De Salvo,
  • Raffaella Mancuso and
  • Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

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  • bar of CO, in CH3CN at 160 °C. By this route, 29 examples were synthesized with isolated yields up to 91% (Scheme 27). One year later, Čarný and co-workers described a facile construction of the isoindolo[2,1-a]indol-6-one structure via a Pd-catalyzed aminocarbonylation and C–H activation reaction
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Published 30 Apr 2024

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

  • Arnaldo G. de Oliveira Jr.,
  • Martí F. Wang,
  • Rafaela C. Carmona,
  • Danilo M. Lustosa,
  • Sergei A. Gorbatov and
  • Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

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  • all other lactams as R was done by analogy. The assignment of the absolute stereochemistry allowed us to propose a rationale for the Heck–Matsuda reaction (Scheme 7). Upon activation of the catalyst (I), oxidative addition of aryldiazonium salt and subsequent nitrogen release generates the cationic
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Published 29 Apr 2024

Synthesis and properties of 6-alkynyl-5-aryluracils

  • Ruben Manuel Figueira de Abreu,
  • Till Brockmann,
  • Alexander Villinger,
  • Peter Ehlers and
  • Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

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  • , only the double-substituted product could be found. No reaction was observed when the reaction temperature was lowered to 0 °C. This could be due to the double activation of the 5-position, despite the fact that bromine is a better leaving group than chlorine. Both positions might be influenced by the
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Published 22 Apr 2024

(Bio)isosteres of ortho- and meta-substituted benzenes

  • H. Erik Diepers and
  • Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

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  • -cubanes (Scheme 9B) [51]. Partial deprotection of diester 88 led to acid 89 as a key intermediate and in situ activation of the acid as the hypervalent iodine complex enabled a photoredox decarboxylative amination to 1,2-cubane 90. Alternatively, conversion of the acid moiety of 89 to redox active esters
  • haloalkylation with alkyl iodides (Scheme 14A) [27][47]. This reaction can be performed either under photoredox catalysis conditions or without the need for an initiator, depending on the used alkyl iodide. For selected examples, the radical initiator Et3B could also be used. Activation by photoredox catalysis
  • was developed by Anderson and co-workers and was shown to be the more versatile than initiator-free activation. Both initiator-free and Et3B-initiated reactions only tolerated electrophilic radicals (to 134a and 134e), while photoredox catalysis also tolerated electron-rich radicals (to 134b). The
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Published 19 Apr 2024

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

  • Ke Jiang,
  • Cheng Pan,
  • Limin Wang,
  • Hao-Yang Wang and
  • Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

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  • have been employed in benzocyclization and arylocyclization reactions, enabling intramolecular cyclization by forming aromatic or heterocyclic rings as a part of cyclic structures [8]. In these reactions, the dual activation of a C–I bond and vicinal C–H bonds/functional groups features a distinct
  • advantage, facilitating the formation of two or more chemical bonds in a step-economic manner [9][10][11][12][13]. In a prior study, we reported a palladium-catalyzed efficient activation of both C–I bond and the adjacent C–H bond of diaryliodonium salts in the formation of 4,5-benzocoumarin derivatives
  • [31][32][33]. Building on our great interest in ortho-functionalized diaryliodonium salts and their dual activation capabilities, we sought to incorporate carboxylic ester groups into the structures of ortho-substituted diaryliodonium salts to explore their properties and reactivity. Our previous
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Published 18 Apr 2024

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

  • Martyn Jevric,
  • Julian Klepp,
  • Johannes Puschnig,
  • Oscar Lamb,
  • Christopher J. Sumby and
  • Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

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  • the byproduct triphenylphosphine oxide, necessitating chromatography which resulted in some hydrolysis. There are a number of catalytic activation strategies for Appel or Mitsunobu reactions such as those described by the Denton group [30], and Rutjes and co-workers [31], and while these may prove
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Published 16 Apr 2024

Advancements in hydrochlorination of alkenes

  • Daniel S. Müller

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

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  • C–H bonds into the alkene π-bond [30]. Before reviewing polar hydrochlorination reactions in detail, it is worth mentioning several statements which were made in the Sergeev review [12]: a) The activation energy for an anti-Markovnikov addition is at least by 30 kJ mol−1 higher than for normal
  • addition. Therefore, anti-Markovnikov products are generally not observed. b) In contrast to the reactions with HBr (peroxide effect) [31][32], the formation of anti-Markovnikov products is low even in the presence of peroxides or photochemical activation. For instance, Whitmore and co-workers observed
  • concerning the polar hydrochlorinations the activation energy for an anti-Markovnikov addition is at least by 30 kJ mol−1 higher than for normal addition. Therefore, the formation of the anti-Markovnikov product via purely cationic intermediates is never observed. The only report for the formation of the
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Published 15 Apr 2024

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

  • Shun Saito and
  • Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

Graphical Abstract
  • been discovered. In this review, we outline the silent gene activation methods, including the authors’ efforts (Figure 1). Review Artificial methods Several target-oriented methods focusing on specific biosynthetic genes and regulatory factors and artificial methods have been reported to activate
  • [46]. Finally, several studies have reported the modulation of secondary metabolic activation in actinomycetes using small molecules. For example, Ochi et al. proposed the “ribosome engineering” technique, in which actinomycetes are cultured with antibiotics to activate secondary metabolism by
  • ribosomal S12 protein mutation results in increased expression of translation factors, which leads to enhanced protein synthesis in secondary metabolism [47]. Liu et al. reported activation of the production of bohemamines 11–13, bacterial alkaloids containing a pyrrolizidine core with two unusual methyl
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Published 10 Apr 2024

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

  • Jan Bartáček,
  • Karel Chlumský,
  • Jan Mrkvička,
  • Lucie Paloušová,
  • Miloš Sedlák and
  • Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

Graphical Abstract
  • chiral metal complex catalyst but also as an enantioselective organocatalyst [17]. Accordingly, its application in enantioselective organocatalysis, particularly in asymmetric reactions through “enamine activation”, warrants further investigation. Results and Discussion The corresponding copper(II
  • -tetrazole, which was successfully used in many asymmetric reactions via “enamine activation”, especially in asymmetric aldol reactions [20][21][22][23]. Moreover, compound IV was previously included in a study dealing with asymmetric cascade reactions (based on aldol reactions) of aldehydes with α-keto
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Published 02 Apr 2024

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

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  • reactions of substituted anilines VI, VII or N-arylamidines VIII are frequently employed for synthesizing C2-substituted quinazolines (Scheme 1), thereby influencing the spatial arrangement of the desired substituents [13][14]. Moreover, there have been recent advancements in efficient C–H activation
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Published 28 Mar 2024

Chemical and biosynthetic potential of Penicillium shentong XL-F41

  • Ran Zou,
  • Xin Li,
  • Xiaochen Chen,
  • Yue-Wei Guo and
  • Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

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  • , given the application of suitable activation techniques. Results and Discussion Compound isolation and structure elucidation To activate the silent BGCs in Penicillium shentong XL-F41, we conducted small-scale fermentations using various media. Analysis revealed that HPLC peaks, which correspond to
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Published 15 Mar 2024

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

  • Yasuhiro Oishi,
  • Motoharu Kitatani and
  • Koichi Kusakabe

Beilstein J. Org. Chem. 2024, 20, 570–577, doi:10.3762/bjoc.20.49

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  • ) linkers on graphene. The activation barrier between two bi-stable conformations exhibited by PASE is confirmed to be based on the steric hindrance effect between a hydrogen on the pyrene group and a hydrogen on the alkyl group of this molecule. Even after the protein is supplemented, this steric hindrance
  • effect remains if the local structure of the linker consisting of an alkyl group and a pyrene group is maintained. Therefore, it is likely that the kinetic behavior of a protein immobilized with a single PASE linker exhibits an activation barrier-type energy surface between the bi-stable conformations on
  • pathway on the adiabatic potential energy surface that connects these conformations caused by the deformation of the PASE linker. The reaction pathway for the conformational change of the PASE itself was found to have a reaction activation barrier [9]. First, we identify that the origin of the barrier is
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Published 11 Mar 2024

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

  • Vladimir P. Rybalkin,
  • Sofiya Yu. Zmeeva,
  • Lidiya L. Popova,
  • Irina V. Dubonosova,
  • Olga Yu. Karlutova,
  • Oleg P. Demidov,
  • Alexander D. Dubonosov and
  • Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

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  • . The reverse reaction 3a–c→2a–c with full restoration of the initial absorption and fluorescence properties was characterized by a high activation barrier and could be accomplished by heating a solution of 3a–c in o-dichlorobenzene at 423 K or by passing dry hydrogen chloride through a solution of 3a–c
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Published 11 Mar 2024

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

  • Ruichen Lan,
  • Brock Yager,
  • Yoonsun Jee,
  • Cynthia S. Day and
  • Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

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  • both within the context of a classic gold π-activation/protodeauration mechanism and a general acid-catalyzed mechanism without intermediate gold alkyls. Keywords: alkene hydroamination; general acid catalysis; gold catalysis; isotope effect; phosphine ligand effect; solvent effect; Introduction
  • Since the seminal 1998 report by Teles et al. on the gold(I)-catalyzed addition of alcohols to alkynes [1], a multitude of gold-catalyzed reactions have been reported. Great successes in mechanistic analysis and synthetic methods have been achieved for allene and alkyne activation, while the activation
  • competing Brønsted acid catalysis in gold-catalyzed alkene functionalization remains a consideration [2], and while it is assumed that alkene activations follow the same prototypical mechanisms as allene and alkyne activations, that is (1) π-activation with nucleophilic attack followed by (2
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Published 29 Feb 2024

Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells

  • Fumihiro Ishikawa,
  • Sho Konno,
  • Hideaki Kakeya and
  • Genzoh Tanabe

Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39

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  • (Figure 1) [3]. The adenylation (A) domain in NRPSs is responsible for the selection and activation of amino acids, hydroxy acids, and aryl acids upon ATP consumption (Figure 2a) [4]. The activated aminoacyladenosine monophosphate (AMP) is transferred to the thiol group of a phosphopantetheine prosthetic
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Published 26 Feb 2024
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