Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• polyketides or peptides, and form an ester bond. Then, they catalyze either intramolecular macrocyclization to give macrolactones or macrolactams with attacking of internal nucleophiles (alcohols or amine), or hydrolysis to release linear acids or peptides (Scheme 1b). Although TE domains may display

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• -15), and COSY correlations shown in Figure 2, clarified the connection of C-1 to C-8 and C-15 to C-11(-C27) through an ester bond. Furthermore, five HMBC, δH 0.99 (H-27)/δC 103.0 (C-10), δH 4.47 (H-32)/δC 206.9 (C-9), δH 4.47 (H-32)/δC 103.0 (C-10), δH 4.47 (H-32)/δC 39.7 (C-11), and δH 3.08 (H-8a

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• (pathway b), while nucleophilic attack at C-14 of intermediate IV by a chloride could generate compound 5 (pathway a). In addition, compound 5 might also be derived from intermediate IV by cleavage of the ester bond at C-2 to form the intermediate VI [15], followed by chlorination (pathway c). Compounds 1

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• of several catalytic domains organized into modules. Typically, a module possesses an adenylation (A) domain for selecting and activating amino- or keto acids, a thiolation (T) domain for shuttling intermediates between catalytic domains, and a condensation (C) domain that catalyzes amide or ester

• bond formation. Additional common domains include epimerization (E) domains for converting naturally occurring ʟ-amino acids to ᴅ-amino acids, methyltransferase (MT) domains that typically methylate specific N atoms, and terminal condensation (CT) domains which cyclize the growing peptide chain and

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• unsaturation required the presence of two heterocyclic rings in the molecule. The presence of an ester carbonyl signal (δC 167.0) and a deshielded oxygenated carbon resonance at C-12′ (δC 104.1) implied the formation of six-membered ring via an ester bond between C-16 and C-12′. In addition, an epoxide moiety

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• to be inactive indicating that the olefin was necessary for cancer cell growth inhibition. For salts 184–187, the authors attributed the decrease in the activity to the lack of phosphatases necessary for the cleavage of the prodrug ester bond and needed to regenerate the drug in the isolated cancer

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• also have increased. The 6-O-capro-β-CD and poly-β-CD-C6 derivatives used in the study are cyclodextrin derivatives with the same core structure. Heptakis(6-O-hexanoyl)-β-CD (6-O-capro-β-CD) is a primary face-modified amphiphilic CD derivative with a 6C fatty acid chain attached via an ester bond to

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

• help of COSY and HMBC data two residues were identified, including a threonine and a salicylic acid moiety. The two partial structures can be connected via an ester bond due to a key HMBC correlation from H-3 to C-5. To analyze the configuration of the isolated compounds, their optical rotations were

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• synthesize brevipolide H (8), but unexpectedly ended up with the isolation of its enantiomer (ent-8) [16]. Common to the most of the reported retrosynthetic analyses of brevipolide, compound 8 is disconnected at the cinnamate ester bond giving β-hydroxy cyclopropyl intermediate 44 and (E)-p-methoxycinnamic

• brevipolide H (8) Two years after the successful synthesis of ent-brevipolide H (ent-8), in 2016, Hou and co-workers reported the first total synthesis of natural brevipolide H (8) [15]. The retrosynthesis was initiated by disconnection of the cinnamate ester bond to give intermediate 79. The 5,6-dihydro-α

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

• . Remarkably, this unit was found to be attached in “reverse” fashion compared to the isoxazolidinone unit in compound 6. The connection via an ester bond of the oxygenated sp3 methine C-11 (δC 71.1) with the carbonyl group of salicylic acid (C-7) was supported by a HMBC cross-peak from H-11 (δH 5.61) to C-7

• through deviation of the salimethyloxazolinyl-thioester intermediate 8 from the assembly line via an unusually facile C–N-bond opening of the ring to generate an ester bond, and followed directly by amination (+ NH3), the addition of histamine and phenethylamine units to form compounds 1, 2, and 3

• exploited for further biological investigation and structure–activity relationship (SAR) studies. To the best of our knowledge, the breakage of the C–N bond of the salimethyloxazolinyl-thioester intermediate leading to an ester bond that resulted in the formation of compounds 1–3 constitutes new plausible

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• decatetraenedioic acid connected via an ester bond. There is also a methoxy group, an epoxide and a terpene derived aliphatic chain that contains another epoxide, linked to cyclohexane. These unstable di-epoxides are responsible for the biological activity of fumagillin, which targets the active site of the

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• weight ratio of 35 was required. The catalyst could be reused, showing significant activity decrease starting from the fourth cycle due to biochar formation. A mechanism was hypothesised in which Zn2+ ions act as a Lewis acid activator for the carbonyl ester bond. In a previous work, complete

• ]. A cooperative mechanism was proposed in which Lewis acid sites (Mg2+, Al3+, Zn2+) activate the C=O ester bond, while the basic sites (OH−) deprotonate EG, enhancing the nucleophilic cleavage of the ester unit [224]. Notably, the depolymerisation of PET by EG was also reported using metal-containing

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• is a mixed anhydride, and therefore it is a highly reactive species, which quickly undergoes further transformation. In the subsequent step, the aminoacyl adenylate reacts with the CCA 3’-end element of bound tRNA, thereby creating an ester bond with the cognate tRNA. The E. coli genome contains

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• of Faes was investigated (Figure 2), measuring 4NTC release by AnFaeA [42] at 40 °C. The enzyme-catalyzed reaction leads to the cleavage of the ester bond linking the ferulate to the linker–4NTC moiety, and thus to the accumulation of linker–4NTC. Therefore, working in a discontinuous mode, 4NTC is

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• pyridine (1 or 2 equiv) as scavengers. Although the reaction slowed down, still a significant cleavage of the tert-butyl ester bond was detected within 24 h (Table 4, entries 4 and 5). This observation might imply that this reaction was similar to the one between carboxyesters and ITMS, and proceeded via a

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• attached to the hydroxy group while in the corresponding ester product (l2–10, Figure 1), C12 is linked to the ester bond, thereby resulting in a change in the chemical shift of H connected with C12. As the chemical shift of H in methyl at 0.87 ppm does not change before and after the reaction, it is used

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• chemistry. The occurrence of an amide and/or ester bond is widely realized in organic molecules, proteins, natural products, pharmaceuticals, polymers and agrochemicals [1][2][3][4][5]. The conventional synthesis of amides involves the reaction of carboxylic acids or their derivatives such as acyl halides

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• , there is no obvious involvement of the ester bond in the binding of 8C2 or 8C4 at these secondary sites. The other main poses of 8C2 and 8C4 present the ligands adopting a linear conformation in a cleft between both monomers of WGA with similar energies (−5.3 to −6.2 kcal mol−1, pose C, Figure 6 and

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

• % isolated yield. However, the reaction of pterostilbene nicotinate with 2,3,5-tri-O-acetyl-α/β-D-ribofuranosyl bromide (7a) in acetonitrile afforded the desired β-anomeric pterostilbene nicotinate riboside bromide in 6% yield only. On both accounts, the lability of the pterostilbene ester bond is likely

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• an ester bond is present. This toxin was subjected to Edman degradation, but this technique provided no information about the composition of the amino acids, suggesting that the amino group at the N-terminus is modified or blocked. However, this toxin was positive for ninhydrin; thus, a basic amino

• dhThr17 and alloThr18 are strictly conserved. Moreover, the conserved alloThr moiety is involved in the cyclic ester linkage. Therefore, the ester bond of natural cichorinotoxin was cleaved by alkaline hydrolysis (0.02 N KOH/MeOH) at room temperature for 5 h to examine the role of the cyclic structure in

• ester bond, was changed into dhThr and that the backbone sequence from the fatty acid moiety to dhThr17 was identical to that of parent cichorinotoxin, but the ester bond was cleaved by the alkaline hydrolysis to yield the linear peptide, as shown in Figure 8 and Figure S18 (Supporting Information File

Synthesis of 3-aminocoumarin-N-benzylpyridinium conjugates with nanomolar inhibitory activity against acetylcholinesterase

• Nisachon Khunnawutmanotham,
• Cherdchai Laongthipparos,
• Patchreenart Saparpakorn,
• Nitirat Chimnoi and
• Supanna Techasakul

Beilstein J. Org. Chem. 2018, 14, 2545–2552, doi:10.3762/bjoc.14.231

• domains. A catalytic triad (CT) that comprises Ser203, His447, and Glu334 residues is responsible for hydrolyzing the ester bond of ACh [20]. The CAS, which is responsible for the binding of the quaternary ammonium moiety of choline, consists of Trp86, Tyr133, Tyr337, and Phe338 [21]. The acyl pocket

Comparative cell biological study of in vitro antitumor and antimetastatic activity on melanoma cells of GnRH-III-containing conjugates modified with short-chain fatty acids

• Eszter Lajkó,
• Sarah Spring,
• Rózsa Hegedüs,
• Beáta Biri-Kovács,
• Sven Ingebrandt,
• Gábor Mező and
• László Kőhidai

Beilstein J. Org. Chem. 2018, 14, 2495–2509, doi:10.3762/bjoc.14.226

• doxorubicin (formerly known as AEZS-108 or AN-152), in which the superagonist [D-6Lys]-GnRH-I allows the tumor targeting of the traditional chemotherapeutical drug doxorubicin covalently linked via an ester bond [3][10]. However, while in the phase II trial, zoptarelin doxorubicin showed promising antitumor

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• spinetoram J (compound 5) was observed, which was the same as the hydrolysis of compound 4. However, during the hydrolysis of analogues 8, none of the 17-pseudoaglycone of spinetoram J, the 9-pseudoaglycone of compound 4, nor compound 2 were observed. It seemed that the ester bond is more stable than the

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• constitutes a nucleophilic partner in a reaction with a carboxyl group (COOH). As a result of derivatization, an amide or ester bond is formed between a graphene-family material and a given chemical. The nature of the derivatization of carboxyl functionalities onto the graphene sheet is directly associated

• for ester bond formation [15]. 4-(N,N-Dimethylamino)pyridine (DMAP) is as an additive in the carbodiimide-coupling protocol. In the second step, DMAP forms active amide intermediates via a reaction with an O-acylisourea individual (Figure 3). This is because DMAP is a stronger nucleophile than the

• alcohol. This leads to the formation of the desired ester bond (Figure 3, step e). DMAP acts both as a nucleophile and an acyl transfer reagent and suppresses the side reactions. The structure of GO includes a number of epoxide moieties, which are also reactive toward the nucleophilic reagents. The

Drug targeting to decrease cardiotoxicity – determination of the cytotoxic effect of GnRH-based conjugates containing doxorubicin, daunorubicin and methotrexate on human cardiomyocytes and endothelial cells

• Livia Polgár,
• Eszter Lajkó,
• Pál Soós,
• Orsolya Láng,
• Marilena Manea,
• Béla Merkely,
• Gábor Mező and
• László Kőhidai

Beilstein J. Org. Chem. 2018, 14, 1583–1594, doi:10.3762/bjoc.14.136

• drug conjugates. Dox has three potential conjugation sites; i) a primary OH group at C-14 on the aglycone part, which is suitable for ester bond formation, ii) an oxo group at C-13 is available for the generation of an oxime linkage and iii) the amino group on the daunosamine sugar moiety, which can be

• used for amide bond formation. The difference between Dox and Dau is the lack of the primary OH group in the case of the latter one. Therefore, Dau cannot be attached to peptide carriers via an ester bond. Mtx contains a glutamic acid whose carboxyl groups are suitable for the attachment to peptides

• through amide bond (this can be carried out on a solid support, prior to the cleavage of the peptide from the resin). In the conjugates used as reference compounds, Dox was coupled to the Lys in position 8 of GnRH-III through glutaric acid linked via an ester bond (O-glut) (1) (similarly to AN-152) or an