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

• Alex De Salvo Raffaella Mancuso Xiao-Feng Wu Laboratory of Industrial and Synthetic Organic Chemistry (LISOC), Department of Chemistry and Chemical Technologies, University of Calabria, Via Pietro Bucci 12/C, 87036 Arcavacata di Rende (CS), Italy Leibniz-Institut für Katalyse e.V., Albert-Einstein

• what we are discussing in this mini-review. Review Carbonylative synthesis of indoles Synthesis of indoles by Pd(0)-catalyzed carbonylation reaction of halide compounds Processes using organic halides as their starting materials involving the oxidative addition of Pd(0) to C–X bonds to give Ar–PdII–X

• complexes are important for the synthesis of heterocyclic and non-heterocyclic compounds. In 2009, Arthuis and co-workers developed a new process for the synthesis of 2-aroylindoles and 2-heteroaroylindoles by a one-pot palladium-catalyzed domino reaction that involves an initial C,N-coupling followed by

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• generate diverse terpene skeletons via sophisticated cyclization cascades. In addition to the many highly selective TSs, there are many promiscuous TSs that accept multiple prenyl substrates, or even noncanonical ones, with 6, 7, 8, 11, and 16 carbon atoms, synthesized via chemical approaches, C

• depyrophosphorylation, whereas class II TSs utilize a general acid (a key Asp residue) to protonate the terminal C=C bond or epoxide group to yield a tertiary carbocation. The highly reactive carbocation is then converted to different carbocation intermediates, facilitated by the hydrophobic pocket of the TSs, which

• TSs and three PTs to generate 4, 5 or geranylfarnesyl diphosphate (GFPP, 29, Figure 1), representative products 30–33 are shown in Figure 3a [28]. Notably, FgMS is a chimeric enzyme (PTTS) consisting of an N-terminal class I TS domain and a C-terminal GFPP synthase domain. Therefore, to block the

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

• Arnaldo G. de Oliveira Jr. Marti F. Wang Rafaela C. Carmona Danilo M. Lustosa Sergei A. Gorbatov Carlos R. D. Correia Department of Organic Chemistry, Chemistry Institute, University of Campinas, Rua Josué de Castro, 13083-970 Campinas, São Paulo, Brazil 10.3762/bjoc.20.84 Abstract We report

• the palladium source in combination with the pyrazinebisoxazoline ligand, (S)-PyraBox (L1), zinc carbonate as base, and methanol as solvent at 40 °C. These initial conditions furnished 2-methoxypyrrolidines arylated at the 4-position, compound 3, as Heck products as illustrated in Scheme 3. The

• temperature gave the NH-unprotected γ-lactam 5a and the drug (R)-rolipram 5b in 79% and 97% yields, respectively, with excellent enantioselectivity. Hydrolysis of γ-lactam 5a in 6 N HCl aqueous solution at 100 °C for 10 hours then led to the formation of (R)-baclofen hydrochloride (6) in 76% yield (Scheme 6

Monitoring carbohydrate 3D structure quality with the Privateer database

• Jordan S. Dialpuri,
• Haroldas Bagdonas,
• Lucy C. Schofield,
• Phuong Thao Pham,
• Lou Holland and
• Jon Agirre

Beilstein J. Org. Chem. 2024, 20, 931–939, doi:10.3762/bjoc.20.83

• Jordan S. Dialpuri Haroldas Bagdonas Lucy C. Schofield Phuong Thao Pham Lou Holland Jon Agirre York Structural Biology Laboratory, Department of Chemistry, University of York, UK 10.3762/bjoc.20.83 Abstract The remediation of the carbohydrate data of the Protein Data Bank (PDB) has brought

• validation report is the beginning of the carbohydrate information, listed as ‘glycans’ in the JSON format. Within this ‘glycan’ scope, information is segmented into glycan types, that is, ‘n-glycan’, ‘o-glycan’, ‘s-glycan’, ‘c-glycan’, and 'ligand'. Each of these glycan types contains an array of individual

• calculated by Privateer and, most importantly, the diagnostic provided by Privateer (Figure 4). A ‘yes’ diagnostic indicates the conformation is correct for the glycosylation type (e.g., 4C1 for GlcNAc in an N-glycan, 1C4 for mannose in a C-glycan), has the correct anomer, and has an acceptable fit to

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

• Lilian M. Maas,
• Alex Haswell,
• Rory Hughes and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2024, 20, 921–930, doi:10.3762/bjoc.20.82

• employed as acylation reagents [1][2][3]. The strong C–F bond makes acyl fluorides relatively stable towards hydrolysis and easier to handle than other acyl halides [4][5][6][7][8]. Their reactions with nucleophiles are typically less violent than for the corresponding acyl chlorides with acyl fluorides

• - or meta-positions all reacted smoothly with 4a to afford the corresponding benzylamides 5a–c in very good isolated yields up to 81%. Electron-donating and -withdrawing groups at the para-position were well tolerated (5d–f), including halogen substituents that could serve as handles for follow-up

• from a self-propagating process initiated by addition of an adventitious nucleophile to the electrophilic thioester. This results in elimination of a (trifluoromethyl)thiolate (−SCF3) anion (C, Scheme 4), which can subsequently undergo β-fluoride elimination, releasing a fluoride anion. Addition of F

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• the reported procedures [41], the Ugi-azide reaction of 2-bromobenzaldehyde (1a, 1 mmol), allylamine hydrochloride (2, 1 mmol), trimethylsilyl azide (3, 1 mmol) and tert-butyl isocyanide (4a, 1 mmol) in MeOH at 40 °C for 24 h afforded 1,5-DS-1H-T 5a in 92% yield after chromatography purification. Our

• first examined by using 10 mol % Pd(OAc)2, 20 mol % PPh3, 2 equiv of Et3N in CH3CN or DMF at 105 °C for 24 h under N2 atmosphere. However, the reactions failed under these conditions (Table 1, entries 1 and 2). When K2CO3 was used as a base to replace Et3N, the reactions in either CH3CN or DMF for 3 h

• to use 1 mmol of 5a with 10 mol % Pd(OAc)2 and 20 mol % PPh3, 2 equiv of K2CO3 in 3 mL CH3CN at 105 °C for 3 h under N2 atmosphere which afforded product 6a in 70% yield (Table 1, entry 3). The combination of an initial multicomponent reaction with post-condensation reactions in one-pot is a good

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

• obtained. Compounds 3a–j were subsequently transformed to 5a–t by Suzuki–Miyaura cross-coupling. The bromination of 1 was performed by using Br2 (1 equiv), Ac2O (1.5 equiv), AcOH (25 °C, 1 h) and yielded the desired product in 52% [62]. With the starting material in hand, initial Sonogashira–Hagihara cross

• using Pd(PPh3)Cl2 (5 mol %), CuI (5 mol %), NEt3 (10 equiv), DMSO, at 25 °C for 6 h as reaction conditions with excellent yield and selectivity. With the optimized conditions in hand, the next step was to investigate the scope and afford 3a–j. The corresponding results are depicted in Scheme 2. The

• effect can be observed for 3e, 3f and 3i. Furthermore, the separation of these products has proven to be more challenging than other compounds with higher yields. In the reaction with 3-pyridylacetylene no product 3g could be obtained. The reaction at 50 °C was found to be chemoselective, giving only the

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• motif in bioactive compounds and the synthetic utility of its olefinic C=C bond. The most extensively explored approach to this transformation is the transition metal-catalyzed C–N coupling between azoles and vinylating agents, including vinyl halides [4], boronates [5], sulfonium salts [6][7][8], and

• performed in 68% and 74% yields, respectively (Scheme 4a). Furthermore, the iodanyl group on these products serves as a versatile handle for downstream transformations, thus allowing for the stereoselective preparation of various trisubstituted N-vinylazoles (Scheme 4b). Pd-catalyzed C–C couplings such as

• Suzuki–Miyaura and Sonogashira couplings on 4aa or 4ba afforded the desired products 5 and 6 in 47% and 74% yields, respectively. In the former case, the C–Br bond on the pyrazole moiety remained intact, highlighting the superior leaving group ability of the BX group. Cu-catalyzed Ullmann coupling

(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

• H. Erik Diepers Johannes C. L. Walker Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany 10.3762/bjoc.20.78 Abstract Saturated bioisosteres of substituted benzenes offer opportunities to fine-tune the properties of drug

• -workers reported a method for the selective bridge bromination of BCPs, giving access to brominated 1,2-BCP (±)-16 (Scheme 2) [33]. By exploiting the homolytic cleavage of the C–Br bond using in situ-generated silyl radicals, they were then able to harness the installed bromide functionality in

• substituted ortho-benzene. Stephenson and co-workers accessed 1,2-BCHeps 79a–c by insertion of alkenes into BCPs 78, and proposed the 1,2-BCHeps as isosteres of ortho-benzenes (Scheme 7A) [46]. The reaction proceeded via homolytic cleavage of a C–C bond adjacent to the imine functionality and stepwise alkene

Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• be produced by feeding prenol and/or isoprenol to the fermentation broth after E. coli being induced by IPTG, and fermented at 18 °C for 72 h. In our hand, feeding a mixture of prenol and isoprenol in a 1:1 ratio would give the best yield of spiroviolene. GC–MS analysis (Figure 2A) of the EtOAc

• BH3·THF in THF, and heated at 60 °C for 3 days. After oxidative treatment of the resultant alkylborane products with NaOH/H2O2, we have obtained three derivatives 9–11 with one hydroxy group in 37%, 30% and 21% isolated yield, respectively, as well as recovery of 10% of the starting material. After

• , respectively. The formation of all three products 9–11 can be explained as follows (Scheme 2A) [28][29][30][31]: Due to the favorable formation of cis-5,5-fused B/C ring system, the borane reagent is preferred to approach the double bond of 1 from the α-face, to give either a secondary 1-organoborane

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

• , herein, we utilized a copper catalyst to activate the C–I bond of diaryliodonium salts in the generation of aryl radicals, thus resulting in an annulation reaction with naphthols and substituted phenols. This approach yielded a diverse array of 3,4-benzocoumarin derivatives bearing various substituents

• 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

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• further characterization. The H73A Vs NnlA variant, previously shown to lack NNG degradation activity, was used as a negative control [21]. E. coli transformants containing the expression vectors were incubated at 37 °C overnight in diluted lysogeny broth (LB) containing NNG and IPTG, the latter component

• deoxygenated 30 mM tricine buffer at pH 7.5 were incubated for one hour at 21 °C in an anaerobic glove box. The samples were analyzed by LC–MS to measure final glyoxylate and NNG concentrations. The extracted ion chromatograms (EICs) showed that NNG was completely consumed and glyoxylate accumulated within the

• 37 °C in diluted LB containing 300 µM 2-NAE. Post-incubation treatment of the samples with Griess assay revealed that all the cultures lacked NO2− (Figure S3, Supporting Information File 1). Combined, these results show that none of the NnlA homologs can degrade 2-NAE. To ensure the lack of 2-NAE

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

• reports of Karban et al. (Scheme 2) [19]. We envisaged that these hexose-derived building blocks with a 2,5-anhydro bond such as 5 could be useful materials for the construction of C-nucleosides such as formycin A (Figure 1) [22][23][24]. The preparation of C-glycosides usually involves the creation of

• the exo-face. This process was used to prepare the known compounds 10a–c, and the novel materials 10d–f [9]. Thus, the reaction of o-dibromoxylene with cyrene gave the alcohol 10d in 71% yield over two-steps through the spirocyclic ketone 9d. Alkylation of 2 with methyl iodide gave an inseparable

• during chromatography, and so an alternate method was developed to generate a single product by promoting the formation of the hemiacetal series 12a–f. Following the rearrangement reaction, chromatography of the chlorides using silica with 2% water added led to the isolation of 12a,c–f in good yield

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus

• Dongxu Zhang,
• Wenyu Du,
• Xingming Pan,
• Xiaoxu Lin,
• Fang-Ru Li,
• Qingling Wang,
• Qian Yang,
• Hui-Min Xu and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73

• genome mining and heterologous expression, we identified a cav biosynthetic gene cluster responsible for the biosynthesis of DMTs 2–4, along with a P450, CavA, responsible for introducing the C-2 and C-3 hydroxy groups. Furthermore, the substrate scope of CavA revealed its ability to hydroxylate drimenol

• diphosphate (DMAPP) from the mevalonate (MVA) and 2-C-methyl-ᴅ-erythritol 4-phosphate (MEP) pathways [2][3]. Sesquiterpenoids, synthesized from farnesyl diphosphate (FPP) which is composed of three C5 units, hold significant biological and industrial value, particularly in the realm of perfumery [4]. Among

• emphasize the potential of DMTs as substances with broad and significant biological activities. The biosynthetic pathways for DMTs, especially for calidoustene C, (+)-isoantrocin, and (−)-antrocin, have been extensively elucidated [6][13][14][15][16][17][18][19][20] (Figure 1b). In the biosynthesis of

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

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

• reaction, the protonation of the alkene is the rate-determining step. This process can be viewed as the reaction between a nucleophile (alkene) and an electrophile (proton). According to the Mayr–Patz equation log(k) = s(N + E), the second order reaction rate constant k at 20 °C for a reaction is related

• 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

• only 10–25% of the primary chloride for the reaction of tert-butylethylene with HCl in the presence of benzoyl peroxide [33]. c) Several metal halides such as AlCl3, SnCl4, FeCl3, and CuCl exhibit catalytic activities for the hydrochlorination of alkenes. The enthalpy of formation for the hydrogen

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• (GABA) at the N-terminus of the Lys pentamer peptide on resin. Using the optimal reaction conditions, three types of hydrophilic peptide pentamers on resin, oligo-Lys (2a), oligo-Glu (2b), and oligo-Arg (2c), were subjected to the reaction with 3 for the synthesis of C60–peptide conjugates 5a–c (Figure

•  1). Results and Discussion Syntheses of C60–oligopeptides 5a–c The oligopeptides 2a–c were synthesized on resin using Fmoc-protected amino acids with a standard SPPS method (Figure 1a) [43]. A moderate loading (0.4 mmol⋅g−1) of the initial amino acid was used. After synthesizing the pentamer of Lys

• acid-substituted C60 derivative 3 and the peptides on resin 2a–c were performed by SPPS to provide the C60–oligopeptides on resin 4a–c (Figure 1a). Subsequently, the last step of the reaction – the cleavage of the C60–peptide conjugate from the resin and the simultaneous deprotection of the amino acid

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• temperature under argon. Under these reaction conditions, the tris(carboranyl)-substituted porphyrin 6 was obtained in 39% yield after purification by column chromatography on SiO2 using CHCl3/hexane 1:1 as eluent (Scheme 3). It should be noted that the reaction of porphyrin 6 with NaN3 in DMSO at 20 °C for

• -dioxaoctane (21) and 1,13-diamino-4,7,10-trioxatridecane (22) in DMSO at 70 °C for 30 min to form amino-conjugates 23 and 24 in 71 and 84% yield, respectively, containing ethylene glycol linkers with terminal primary amino groups (Scheme 6). The presence of ethylene glycol residues in bioactive molecules is

• cytoprotective and therapeutic actions. It is synthesized from cysteine and is excreted without any further metabolism [47]. The reaction of taurine (25) with porphyrin 6 proceeded in DMSO at 20 °C for 72 h to afford taurine-containing conjugate 26 in 78% yield (Scheme 6). Conjugates 19, 23, 24, and 26 can be

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

• chaxalactins A–C (16–18), and polycyclic polyether natural products designated terrosamycins A and B (19, 20), respectively [55][56]. Thus, the OSMAC strategy has been successfully applied over the last 10 years to generate new secondary metabolites from a single microbial strain. Sensor proteins for medium

• heat shock at 42 °C for 1 h [70]. Similarly, James et al. increased the production of granaticin (31) by Streptomyces thermoviolaceus NCIB 10076 by changing the culture temperature [71]. They showed that the yield was best at 45 °C, whereas the rate of synthesis was highest at 37 °C. However, there

• was searched to identify actinomycete strains capable of growing at high temperatures (45 °C). This screening identified 57 actinomycete strains capable of growing at 45 °C. Comparative analysis of metabolites produced by these 57 actinomycetes at room temperature or high temperature revealed that

Research progress on the pharmacological activity, biosynthetic pathways, and biosynthesis of crocins

• Zhongwei Hua,
• Nan Liu and
• Xiaohui Yan

Beilstein J. Org. Chem. 2024, 20, 741–752, doi:10.3762/bjoc.20.68

• isolated from the fruit of Gardenia jasminoides Ellis and the stigma tissue of Crocus sativus L. Crocins are the main active ingredients of C. sativus, a precious medicinal plant known as the "gold of spices". They are also responsible for the characteristic red color of saffron. Compounds of the crocin

• family are the monoglycosyl, diglycosyl, or triglycosyl products of 8,8′-diapocarotene-8,8′-dioic acid (crocetin, 1) or derivatives thereof. In addition to C. sativus and G. jasminoides, Buddleja officinalis and Buddleja davidii from the Loganiaceae family [1][2], Nyctanthes arbor-tristis from the

• , etc. For example, during the harvest of C. sativus, a high drying temperature leads to the cleavage of the glycosidic bonds [20][21][22]. Crocins are stable in alkaline and neutral solutions but are labile under acidic solutions. Crocins can be detected in the flowers, fruits, stigmas, leaves, and

Substrate specificity of a ketosynthase domain involved in bacillaene biosynthesis

• Zhiyong Yin and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2024, 20, 734–740, doi:10.3762/bjoc.20.67

• His-tagged enzyme was obtained through heterologous expression and purification by Ni2+-NTA affinity chromatography (Figure S1, Supporting Information File 1). After incubation of the purified enzyme with the 13C-labelled SNAC derivatives (S)-11 or (R)-11 for 30 minutes at 25 °C, the incubation buffer

• buffer exchange (5 centrifugations); C) the filtrate obtained from the incubation of (R)-11 BaeJ-KS2 containing free (R)-11 (first centrifugation); D) the filtrate from the same experiment containing no (R)-11 (fifth centrifugation); E) the filtrate obtained from the incubation of (R)-11 with BaeJ-KS2

• -labelled carbons. Biosynthetic model for bacillaene (1). M1–M17 indicate modules 1–17. A = adenylation domain, ACP = acyl carrier protein, AT = acyltransferase, C = condensation domain, DH = dehydratase, KR = ketoreductase, KS = ketosynthase, MT = methyltransferase, PCP = peptidyl carrier protein, TE

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

• essential domains, namely adenylation (A), condensation (C), and peptidyl carrier protein (PCP). Each type I PKS module consists of three core domains containing acyltransferase (AT), ketosynthase (KS), and acyl carrier protein (ACP). PCP and ACP are collectively called thiolation domain (T). The sequence

• -century [32][33][34][35]. Biosynthetically, the corresponding cluster consists of three NRPS, TycA-C, and at the C-terminus of TycC, the TE domain can catalyze a head-to-tail macrocyclization and deliver tyrocidines [30]. With a comprehensive understanding of its biosynthetic mechanism, Walsh and co

• macrolactones. Using engineered variants of S. venezuelae ATCC 15439 designated strains DHS200141 [71] and YJ11242 [72], 24 and 25 were transformed to the corresponding macrolides through whole cell biotransformation to append ᴅ-desosamine and perform C–H oxidation(s) by the PikC monooxygenase (Scheme 6b). In

Genome mining of labdane-related diterpenoids: Discovery of the two-enzyme pathway leading to (−)-sandaracopimaradiene in the fungus Arthrinium sacchari

• Fumito Sato,
• Terutaka Sonohara,
• Shunta Fujiki,
• Akihiro Sugawara,
• Yohei Morishita,
• Taro Ozaki and
• Teigo Asai

Beilstein J. Org. Chem. 2024, 20, 714–720, doi:10.3762/bjoc.20.65

• HREIMS spectrum. The 1H and 13C NMR spectra of 1 were identical to those of sandaracopimaradiene [30][31]. As the specific rotation of compound 1 was in good agreement with the reported data ([α]D24 −14.3 (c 0.97, CHCl3) in this study; [α]D25 −10.29 (c 0.65, CHCl3) in the literature [31]), compound 1 was

• clusters containing AsCPS and AsPS. B) Domain organization of AsPS and AsCPS. C) Domain organization of CiCPS-PS. GC–MS analysis of the A. oryzae transformant. A) TIC of the extracts obtained from AO-AsGGS/AsCPS/AsPS and A. oryzae NSAR1. Compound 1 was identified to be a product, while the other minor

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• , greatly increasing the molecular complexity of the starting substrate. Using radical chemistry would lead to a regioselective addition of azide radicals to the alkene, forming selectively the most stabilized C-centered radical. A prominent method for the generation of azide radicals relies on hypervalent

• would initially involve the addition of azide radicals to an alkene, generating a carbon-centered radical. Then, different trapping of this intermediate could be performed (Scheme 1B). First, C-centered radicals are known to recombine with metal-acetylides, in particular copper [27]. Reductive

• alkyne substituent. Arylalkynes are expected to perform well but in multiple cases alkyl substituents were reported to afford low yields or no reaction [35][36][37][38]. Finally, a radical-polar crossover (RPC) approach could be envisaged [39][40]. Instead of attempting to trap the C-centered radical

New variochelins from soil-isolated Variovorax sp. H002

• Jabal Rahmat Haedar,
• Aya Yoshimura and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2024, 20, 692–700, doi:10.3762/bjoc.20.63

• structure – a linear hexapeptide with β-hydroxyaspartate and hydroxamate functional groups, serving in iron-binding coordination. Three new variochelins C–E (3–5) were characterized by varied fatty acyl groups at their N-termini; notably, 4 and 5 represent the first variochelins with N-terminal unsaturated

• this study, we isolated three new congeners of variochelin-type siderophores, variochelins C–E (3–5), along with two known compounds, variochelins A (1) and B (2), from Variovorax sp. Their structures were elucidated by a combination of NMR, ESIMS/MS, and chemical derivatization. The analysis of the

• deduce the fatty acyl moiety in 3 as an decanoic acid. Thus, we determined 3 to be a new siderophore termed variochelin C, with an N-terminal decanoate. Compound 4 has the chemical formula of C47H81O17N11, as suggested by HRESIMS (m/z 534.7837 for [M − 2H]2− ion), inferring the loss of two hydrogen atoms

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

• (i.e., temperature, reaction time, amount of catalyst, solvent) were adopted from the pilot study [5] for relevant comparison of catalyst characteristics. From Table 1 and Table 2, which summarise results obtained using tridentate ligands Ia–c and IIa–c, it is evident that the catalytic activity their

• the C=O bond. In this manner, the asymmetric induction results in the restricted addition of nitromethane influenced by imidazolidin-4-one moieties. The higher enantioselectivity of complexes of the ligands with cis-cis configuration could be explained by the fact that the larger (RL) alkyl group is

• . Thus, early attempts at the aldol reaction of 4-nitrobenzaldehyde with cyclohexanone were performed to evaluate the reaction parameters, i.e., solvent, reaction temperature, and amount of acidic additive (Table 5). Hence, using DMF at −25 °C were the most convenient conditions regarding diastereo- and