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

• by diamonds. EIMS of DMOX derivatized free fatty acids derived from variochelins C–E (3–5). (a) 3, (b) 4, and (c) 5. (a) Plausible biosynthetic pathway of variochelin A–E (1–5). The circles represent domains: A: adenylation domain, C: condensation domain, PCP: peptide carrier protein, E

HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines

• Luan A. Martinho and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55

• (insomnia). Some recent synthetic approaches to imidazo[1,2-a]pyridine scaffolds include synthetic pathways of transition metal-catalyzed reactions [14], cyclization [15], condensation [16], heteroannular [17], and photocatalytic reactions [18]. These approaches usually involve non-trivial reaction

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• ][26][27]. The unique Schiff base 6 can however be stored without precautions for several months without degradation and is prepared with minimal processing in 75% yield by telescoping the annulation and condensation steps. As the 4-aminooxazole motif appeared to be a poor nucleophile, we sought to

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

• is widely used as a linker to connect carbon materials and proteins (Figure 1a) [1][4][5]. The PASE linker and a certain protein can be connected through a dehydration condensation reaction so that the succinimidyl ester group is replaced by an amido group with a protein (Figure 1b). This dehydration

• , respectively. The solid, broken, and dotted red lines represent the rotation axis. Atomic geometry is visualized by Xcrysden [10] throughout this paper. (b) Schematic diagram of the dehydration-condensation structure of a hypothetical protein and PASE. Lys indicates lysine, and RC is the active center of the

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

• ]thiophene-3(2Н)-ones 2a–c with a terminal phenanthroline substituent was (E)-2-(((1,10-phenanthrolin-5-yl)amino)methylene)benzo[b]thiophen-3(2H)-one (1), obtained by condensation of 3-hydroxybenzo[b]thiophene-2-carbaldehyde with 5-aminophenanthroline in acetonitrile (Scheme 1). (Z)-N-((3-Oxobenzo[b]thiophen

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

• arm in an adjacent peptidyl carrier protein (PCP). The amino acid loaded on the PCP then undergoes coupling with the amino acid loaded on the downstream PCP in the condensation (C) domain. Finally, the linear peptide on the PCP in the last module is either hydrolyzed or cyclized by a thioesterase (TE

• -specific A-domain; A2, ʟ-Pro-specific A-domain; A3, ʟ-Val-specific A-domain; A4, ʟ-Orn-specific A-domain; A5, ʟ-Leu-specific A-domain; E, epimerization domain; C, condensation domain; TE, thioesterase domain. (A) Adenylation reaction in a nonribosomal peptide synthetase. (B) Structures of aminoacyl-AMS

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• -inflammatory, and even anticancer agents. Traditionally, the synthesis of BIMs has been achieved upon the acidic condensation of an aldehyde with indole, utilizing a variety of protic or Lewis acids. However, due to the increased environmental awareness of our society, the focus has shifted towards the

• research group explored the activity of cadmium sulfide (CdS) nanotubes as heterogeneous nanocatalysts for the electrophilic condensation between aldehydes and indoles [106]. The nanorods were obtained with a solvothermal technique, where thiourea and cadmium nitrate were mixed in ethylenediamine for 10

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• condensation and Schiff base formation, which is then cyclized [12][16]. The reaction of 1 with arylamines 2a is performed in toluene solution in the presence of a catalytic amount of p-toluenesulfonic acid. This readily affords 6,8-di-tert-butyl-N-aryl-3H-phenoxazin-3-imines 3 but proceeds smoothly only with

• condensation of 3H-phenoxazin-3-one (1) with various o-aminophenols (in refluxing DMF for 8–10 h), upon formation of the corresponding imine intermediate, affords benzo[5,6][1,4]oxazino[2,3-b]phenoxazines derivatives 10a,b (triphenodioxazines). As shown in the present work, this reaction can also be performed

• and oxazinophenothiazine derivatives 10 via condensation of 3H-phenoxazin-3-one 1 with o-aminophenol and o-mercaptoaniline derivatives 2d. UV–vis absorption data of 6,8-di-tert-butyl-2-(arylamino)-3H-phenoxazin-3-ones 4a–h in toluene. UV–vis absorption and fluorescence emission data of compounds 5a–c

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 the UngA NRPS were analyzed in an attempt to understand the lack of substrate specificity observed. Keywords: adenylation domain; condensation domain; fungal non-ribosomal peptide synthetase; heptapeptide; unguisin biosynthesis; Introduction Unguisins are a small family of fungal cyclic

• 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

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• properties, so far. Therefore, we have synthesized selected benzo[c]quinolizinium derivatives and studied their DNA-binding and DNA-photodamaging properties. Results and Discussion Synthesis The styrylpyridine derivatives 2a,c,d,f were synthesized by a piperidine- or Ca(OTf)2-catalyzed condensation reaction

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• as a mixture of E and Z isomers (ca. 4:1). Further functionalization of the IF-DTF ketone 11 was obtained by Ramirez/Corey–Fuchs dibromo-olefination and Knoevenagel condensation to yield vinylic dibromide 14 and diester 15, respectively, as illustrated in Scheme 2. We noted that the dibromo

• 11 via Ramirez/Corey–Fuchs dibromo-olefination and Knoevenagel condensation. Coupling of 1,3-dithiole-2-thione building blocks 2 and 3 with fluorenone 5 to afford fluorene-extended DTFs 16 and 17. Synthesis of acetylenic scaffolds based on IF-DTF. Conditions: (a) Pd(PPh3)2Cl2, CuI, THF, Et3N, rt. (b

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• the aldol condensation products. Importantly, the ability to recycle the ionic liquid in subsequent reactions was successfully demonstrated. Keywords: alkyne hydration; boron trifluoride; electrochemical synthesis; ionic liquids; Introduction Alkynes are fundamental starting materials towards more

• . Hydration of phenylacetylene 1d carried out with 3 equiv of BF3·Et2O for 5 h gave the aldol condensation product 3d (58%) in addition to acetophenone 2d with low yield (32%) (see Table S1, Supporting Information File 1). Assuming that enone 3d is formed from acetophenone, catalysed by the excess Lewis acid

• selectively obtained without the aldol condensation products. Considering 4-methylphenylacetylene (1e), the reaction carried out with 3 equiv of BF3·Et2O for 5 h gave only the condensation product 3e (70%, see Table S1, Supporting Information File 1). Reducing the amount of BF3·Et2O to 1 equiv and the

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• -containing azaacenes Bunz and co-workers incorporated biphenylene units into azaacene structures to enhance their stability [45]. Initially, their early attempts focused on synthesizing unsymmetrical azaacenes containing biphenylene units. Through the condensation of ortho-diamine compounds 53a–c derived

• ) [46]. This complexity arises from factors such as limited substrate versatility and the difficulty in incorporating solubilizing groups into the symmetric azaacene framework. In the initial stage, the condensation reactions between biphenylene-2,3-dione (52) and diaminothiadiazoles 55a,b resulted in

• the formation of polycyclic structures 56a and 56b containing thiadiazole units, in yields of 57% and 34%, respectively. Subsequently, by selectively cleaving the thiadiazole ring using LiAlH4, followed by further condensation reaction with dione 52, the desired symmetric azaacenes 58a and 58b with R

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• were between 7–18%. Synthesis of tripyrrane 5 5,10-Bis(4-trifluoromethylphenyl)tripyrromethane (5) was obtained as side product of dipyrromethane synthesis by the condensation of pyrrole and 4-(trifluoromethyl)benzaldehyde. A typical procedure involves 4-(trifluoromethyl)benzaldehyde (28.7 mmol) and

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• intermediate β-enamino amides 2 are easily available by condensation of the corresponding β-keto amide 1 and an amine (Scheme 1, conditions i). As the amine here plays only an auxiliary role, for the purpose of this research we opted for inexpensive ethylamine. Compounds 2 were obtained by simply stirring a

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• equivalents to react with various nucleophilic reagents [90]. In 2014, Heimgartner et al. first developed the condensation reaction of a commercially available fluoral hemiacetal with acylhydrazides to yield trifluoromethylated acylhydrazones, and these fluorinated compounds underwent heterocyclization

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• -Aldrich and Vetec in the highest purity available and used without further purification. Syntheses of the compounds Compounds were synthesized by modifying the existing methodology in the literature [50]. The compounds were prepared by condensation between 3,4,5-trimethoxybenzoic acid hydrazide (TMP, 1.0

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• applications. Secondly, the feasibility of synthesizing quinoxalines contributes immensely to their appeal. Qxs can be readily prepared through simple condensation reactions, enabling convenient experimental studies and cost-effective bulk production [5]. The availability of inexpensive and accessible starting

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• Pharmacy, Changzhou University, Changzhou 213164, China 10.3762/bjoc.19.123 Abstract The [3 + 2] cycloadditions of stabilized azomethine ylides (AMYs) derived from amino esters are well-established. However, the reactions of semi-stabilized AMYs generated from decarboxylative condensation of α-amino acids

• with arylaldehydes are much less explored. The [3 + 2] adducts of α-amino acids could be used for a second [3 + 2] cycloaddition as well as for other post-condensation modifications. This article highlights our recent work on the development of α-amino acid-based [3 + 2] cycloaddition reactions of N–H

• : A1-type AMYs can be generated from the condensation of aldehydes with α- and N-dialkylglycine esters, A2-type AMYs are derived from α-alkylglycine esters, A3-type AMYs are derived from N-alkylglycine esters, and A4-type AMYs are derived from glycine esters. Stabilized zwitterions A1–A4 have the

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• [12][13][16][19][26]. 1H derivatives can be obtained in a number of ways, including direct condensation of N,N'-dimethylphenylene-1,2-diamine derivatives with the appropriate aldehydes, YCHO [24][27], or borohydride reduction of 1+ salts [24]. The cations conversely can be obtained from 1H derivatives

• , for example through hydride abstraction by Ph3C+ [13]. Alternatively, they can also be obtained by condensation of N,N'-dimethylphenylene-1,2-diamine derivatives with acid chlorides, YCOCl, or through the methylation of 2-substituted benzoimidazoles [24], which in turn can be obtained from

• condensation between phenylene-1,2-diamines and carboxylic acids YCO2H [28], oxidative condensation between YCHO and phenylene-1,2-diamines [29], or reductive condensation between YCHO and 2-nitroanilines [24]. In this work we condensed the appropriate YCHO aldehyde (II) and 1,2-diaminobenzene (I) derivatives

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• synthesis of these compounds involved the condensation of a meso-disubstituted dipyrromethane with diamines incorporating the crown ether/azacrown segment in the presence of boron trifluoride diethyl etherate as a catalyst [66]. The treatment of compound 16 with potassium hydride yielded 16-K2, a suitable

• also demonstrated the crowned fused expanded porphyrinoids incorporating a pyridine moiety [135]. Macrocycles 45 were obtained in 5–10% yield from the condensation of 38 with the corresponding pyridine-based dipyrromethane analogue. Compound 45 exhibited a unique structural arrangement, with the

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• Knoevenagel condensation of rhodanine with different aldehydes [3]. The reactions were performed in ChCl/urea (1:2) at 90 °C, without needing a catalyst and the products were obtained in low to good yields (10–78%). On another hand, ʟ-proline is well known as an organocatalyst and its use in aldol and

• Knoevenagel condensation is well documented [21]. Moreover, the low cost and high availability of ʟ-proline has attracted attention to ʟ-proline-based DES. Especially, in 2022, Detsi [20] has synthesized and characterized three ʟ-proline-based NaDES: proline/oxalic acid (1:1), proline/glycerol (1:2), and

• proline/lactic acid/water (1:2:2.5). The authors studied their use in the synthesis of aurones via a Knoevenagel condensation and compared them to the classical choline-based DES, ChCl/Gly (1:2). They demonstrated that the ʟ-proline-based DES were superior to ChCl/Gly and obtained aurones from the

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• carried out by condensation of acetophenones with chloral under reflux in acetic acid using the known literature procedure [19] (Scheme 2). Based on another literature approach [20], compounds 1p–v were obtained by acylation of electron-donating arenes with Wynberg lactone [21] (Scheme 3). Additionally

• condensation of acetophenones with chloral in refluxing acetic acid. Synthesis of 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones 1p–v by acylation of electron-donating arenes with Wynberg lactone. Synthesis of 1-aryl-4,4,4-trichlorobut-2-en-1-ones 2 by dehydration of hydroxy ketones 1. Cyclization of 1-aryl

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• protodemetalation to provide ultimately the 1,4-addition adduct. In the presence of carbonyl acceptors, aldol condensation occurs providing overall a tandem 1,4-addition–aldol process. When a tert-butanesulfinyl moiety is present on the nitrogen atom, these electrophilic substitution reactions occur with good

• carbonyl compounds to provide the corresponding zinc enolates (Scheme 1) [1][2]. While simple, this reaction offers attractive features: 1) it proceeds under mild conditions in the absence of any transition-metal catalyst; 2) the 1,4-addition step can be combined with condensation reactions of the zinc

• thus the sense of chiral induction for the 1,4-addition reactions reported in Table 2. Tandem 1,4-addition–aldol condensation reactions We then went on to consider tandem 1,4-addition–aldol condensation reactions (Scheme 6), which offer the interesting prospect of generating an all-carbon quaternary

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• acyloins (Scheme 1a). Anand’s group [25] demonstrated that a NHC-catalyzed selective acyloin condensation between aromatic aldehydes and trifluoroacetaldehyde ethyl hemiacetal afforded the analogous products (Scheme 1b). In comparison, the synthesis of trifluoromethyl aliphatic acyloins is still