Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• approach for constructing Morken’s C2–C12 fragment In 2019, Uguen and co-workers introduced a strategy to assemble Morken’s C2–C12 intermediate 20 [41]. Their approach utilized iterative base-catalyzed condensation of sulfone compounds with epoxides. As illustrated in Scheme 1, the monoalcohol 20 was

• prepared via PMB removal of compound 21, which, in turn, was obtained through desulfonylation of compound 22. Compound 22 originated from the condensation of epoxide 23a with sulfone 26, which was produced by desilylation of 25 followed by converting the resulting primary alcohol into a sulfone group

• . Intermediate 25 was prepared through TBDMS protection and desulfonylation of 24, itself derived from the condensation of epoxide 23b and sulfone 27. The precursor 27 was synthesized from Roche ester 29 via a sequence of steps, including reduction, three-carbon homologation, and enzymatic desymmetrization. An

Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

• Linqiang Wang and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

• [5] and the FDA-approved antibiotic linezolid [6] (Figure 1). Both chiral oxazolidines [7][8] and oxazolidinones [9][10] have been utilized as chiral auxiliary groups in many asymmetric organic transformations. Oxazolidine derivatives have been prepared mainly from condensation of vicinal amino

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• aldol condensation of 5 provided the tetracyclic α,β-unsaturated enone 6 in 57% yield. Subsequent catalytic hydrogenation using Pd/C conditions delivered the hydrogen to the alkene from the less hindered face, producing ketone 7 with high diastereoselectivity. Final reduction of both the amide and

• intermediate would meet challenges associated with the instability of enolate derivatives. In their recent study, they successfully developed such a polycyclization taking advantage of a novel spiropyrroline-derived oxazole (SPDO) ligand (L3). As shown in Scheme 7, one-pot condensation of primary amine 40, β

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• hydrogenation of the C=C double bond in the side chain gave brevicarine (2). The first total synthesis of brevicarine is shown in Scheme 3 [2][20][21]. Condensation of indole (11) with 1-methylpiperidone (12) gave compound 13 [22]. N-Alkylation of 13 with benzyl bromide, followed by treatment of the quaternary

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

• Zhiyang Zhang,
• Jialei Hu,
• Hanfeng Ding,
• Li Zhang and
• Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

• essential tertiary alcohol at C1. The β-hydroxylactone moiety (D ring) in 11 could be introduced through an intramolecular aldol condensation [35] of acetate 12. Ultimately, the preparation of 12 could be traced back to aldehyde 14 through 1,2-Grignard addition with an organomagnesium reagent [36] prepared

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• intramolecular condensation with the arylglyoxal-derived keto-carbonyl group [37]. In 2024, the same group streamlined this strategy by utilizing unprotected anthranilic acids, enabling the assembly of benzo[e][1,4]diazepines 6 directly during the Ugi reaction step [38]. In 2013, Van der Eycken and co-workers

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• structurally diverse macrocycles through the dynamic self-assembly of α,α’-linked oligopyrrolic dialdehydes and alkyldiamines (Scheme 10) [39]. Their investigation revealed distinct solvent-mediated selectivity in product formation. Condensation of the pyridine-bridged oligopyrrolic dialdehyde 37 with simple

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• single-crystal X-ray diffraction [19]. According to a previous publication, the condensation between pyrrolidine-2,3-diones and an amine as nucleophile normally occurred at the 3-position of nitrogen-containing heterocyclic ring which results in the corresponding enamine product [18]. However, the

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• nucleophilic aromatic substitution of 4-fluorobenzaldehyde with 2-(methylamino)ethanol, 3-methylamino-1-propanol or 2-[2-(methylamino)ethoxy]ethan-1-ol in the presence of potassium carbonate to afford benzaldehyde derivatives 1, 2, and 3 in excellent yields. Next, the piperidine-induced condensation with 4

• monitored by the inherent fluorescent signal of the target RNA [11]. The synthetic route to such an HBC fluorophore is shown in Scheme 6. Piperidine-induced condensation of compound 2 with 4-iodophenylacetonitrile afforded the HBC-like ligand, whose hydroxy group was immediately protected with TBS-Cl to

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• of chemoselectivity becomes important when formaldehyde is used. Moreover, primary amines (alkyl- and arylamines) can also react with two equivalents of both the formaldehyde and the P(O)H compound. In this case, a double Kabachnik–Fields condensation gives bis(phosphorylmethyl)amines 34 as possible

• (Scheme 30). As glyoxylates are C2 structures, their use as C1 building blocks in MCRs instead of formaldehyde, requires an extra path, usually a decarboxylation process, after the condensation reaction. However, by appropriately choosing the glyoxylate derivatives (for example, ethyl glyoxylate), post

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

• with diverse N-nucleophiles was investigated. It was shown that the direction of the process depends on the type of employed nitrogen-containing reagent. For example, condensation with aliphatic amines leads to 2H-furo[3,2-b]pyran-2,7(3H)-diones bearing an exocyclic enamine moiety. At the same time

• under various conditions. Initially, we performed the studied process with equivalent amounts of starting materials in ethanol at reflux for 1 h. As a result, no products of condensation or recyclization have been obtained. At the same time, stable salt 3a was isolated in 95% yield (Scheme 2a). Besides

• ). Apparently, for the realization of the presented condensation, the nucleophilicity of the aromatic amines is not sufficient. Wherein, the type of substituent in the aroyl fragment of furanone 1 doesn’t influence the result of this reaction. Thus, enamines 4 can be synthesized only using active aliphatic

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• ). As shown in Scheme 2, in the initial step, the aldol condensation of 2,3,3-trimethylindolenine 2 with o-chloranil (3) leads to the intermediate compounds, 6-(2-hetarylmethylene)-6-hydroxy-2,4-cyclohexadien-1-ones 4. Such intermediates were isolated preparatively and structurally characterized in the

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• generate crotonic condensation adducts of active methylene compounds and formaldehyde at room temperature in the absence of strong acids and bases. The formed adducts were highly reactive intermediates capable of reacting with dienes in a three-component reaction, leading to the formation of Diels–Alder

• main reaction products. Keywords: aldol condensation; [4 + 2]-cycloaddition; diffusion mixing; formaldehyde; Knoevenagel condensation; three-component reactions; Introduction Formaldehyde is a reactive electrophilic reagent widely used as a C1 building block in multicomponent reactions [1][2][3]. Its

• role in most cases is to generate highly reactive species in situ from the nucleophilic reaction component. This can subsequently interact with other reaction components to form target products. Compared to the crotonic condensation products of other aliphatic and aromatic aldehydes, methylidene

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• condensation of carboxylic acids with anilines, often promoted by activating agents such as thionyl chloride or peptide coupling agents [86][87][88][89]. However, these protocols rely on environmentally harmful reagents and produce unwanted byproduct wastes. Recently, the research group of Son showcased a

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• reactions conducted step by step. Providing acyclic compounds A three-component Strecker-type condensation of aromatic aldehydes, amines, and cyanides under mild reaction conditions furnishes α-aminonitriles 1 in good to high yields (Scheme 1) [15]. The reaction failed only in the case of acetophenone

• Pd-catalyzed cross-coupling reactions, allowing the formation of C–C and C–N bonds in the o-position of the aryl chalcogen compounds. α-Aminophosphonates 14 were the result of a one-pot condensation of an aldehyde, a primary amine and phosphite P(OMe)3 with copper triflate acting as Lewis acid

• realized with high diastereo- and enantioselectivities (Scheme 12) [25]. Providing cyclic compounds For more than a century, Biginelli's reaction has been known as an effective tool for the construction of dihydropyrimidines through a three-component process by condensation in an acidic medium of an

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• process was inspired by the biocatalytic synthesis of aromatic polyketides by polyketide synthase from poly β-carbonyl substrates. Pyrrolidine-based organocatalyst C4 was able to promote a twofold atroposelective arene-forming 6-enolendo aldol condensation (Scheme 4). Sparr also realized a central-to

• [27]. This transformation led to a series of axially chiral cycl[3.2.2]azines 24 in good yields and high enantiomeric purities (Scheme 8). The proposed mechanism comprises enamine activation, condensation with nitroolefin 23, ring closure, and catalyst elimination to provide the axially chiral product

• reaction pathway was proposed [56]. The first step is a CPA C27-catalyzed condensation giving rise to the imine intermediate followed by isomerization to the enamine stabilized by CPA. An enantioselective intramolecular cyclization followed by dehydration then afford the aromatic ring and desired product

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• /CH2Cl2 at room temperature (17% yield). Subjecting the methoxylated benzaldehyde intermediate 9 to a Doebner–Knoevenagel condensation with malonic acid and pyridine afforded the brominated cinnamic acid analogue 10 in 54% yield [19]. Amidation chemistry using carbonyldiimidazole (CDI) [18] and the

• (4-OCH3); LRESIMS (m/z): 293/295/297 [M + H]+. Doebner–Knoevenagel condensation of 3,5-dibromo-4-methoxybenzaldehyde with malonic acid 3,5-Dibromo-4-methoxybenzaldehyde (9, 80.0 mg, 0.27 mmol), malonic acid (56.0 mg, 0.54 mmol) and dry pyridine (1 mL) were refluxed at 100 °C for 5 h. The reaction

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• quinazolinone scaffold. They have obtained new benzochromenopyrimidinones, abbreviated as BCPOs, whose synthesis has been accomplished in two steps. First, a microwave-assisted reaction of ethyl cyanoacetate, selected aromatic aldehydes, and 2-naphthol was performed. The second step was the condensation of the

• a multicomponent reaction to obtain SIRT2 inhibitors (Scheme 12). The authors suggest a Knoevenagel condensation approach between isatin derivatives and ethyl cyanoacetate, followed by a Michael addition with C–H activated carbonyl compounds and intramolecular cyclization [50]. They synthesized 45

• as nitro or azide groups, rather than protected amines. Following the Ugi-4CR, the nitro or azide group is reduced to form the amine, leading to a condensation reaction that results in the formation of the benzodiazepine ring [55]. Pertejo et al. [61] described the diastereselective synthesis of 3

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• [58] was prepared in the first step via three-component reaction between tetracyanoethylene, cyclopentanone, and hydrogen chloride. Then, multiacceptor compound 2 was involved in the condensation with aromatic aldehydes bearing electron-donor groups. As a result, a series of new push–pull molecules

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• transport properties was most clearly observed in compound 3b which has a 60-fold improvement in mobility compared to 2b. This study demonstrates that the choice of the solubilising group has a profound effect on the hole mobility on these organic semiconductors. Keywords: Knoevenagel condensation; organic

• the Knoevenagel condensation with malononitrile was successfully reported [33]. Theoretical studies Density functional theory (DFT) calculations of two derivatives of compounds 2 and 3, having methoxy groups instead of the longer alkyl chains have been reported in the literature [32], providing

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• application of the Mukaiyama redox condensation using N-iodosuccinic imide (NIS) afforded 10b. Hydrogenation resulted in defunctionalization to give 10c. Transformation of OH-4 to a triflate and subsequent reaction with sodium azide afforded gluco-configured product 10d. The latter was transformed to

• condensation of anomerically pure β-configured β-16a with indoxyl acetate, in the presence of an excess of sodium carbonate, afforded β-configured indirubin-N-rhamnoside β-17a in very good yield as the pure Z-configured isomer (Scheme 13) [22]. Gratifyingly, the product, which showed the characteristic red

• color of indirubin, was directly obtained in its deprotected form. Indirubin-N-rhamnoside β-17a is significantly more stable than indigo-N-rhamnoside 5c. Likewise, starting with 3,5-dimethylaniline, the β-configured indirubin-N-rhamnoside β-17b was prepared. Rhamnoside 17c was prepared by condensation

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• reactivity [36]. Borolanylporphyrins can be synthesized by Miyaura-borylation of the halogenated porphyrin [24][37]. There are also reported instances of borolanylporphyrins being synthesized under condensation conditions [36][38]. Despite the many synthetic advancements for the decoration of porphyrins

• , 12, and 13 had to be synthesized (Scheme 1). The synthetic route to achieve OET-xBrPPs (2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetra(x-bromo)phenylporphyrin, where x = ortho/meta/para) pyrrole 7 was synthesized through literature procedures [40][41]. Pyrrole 7 was then subjected to condensation

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

• Yuta Kabumoto,
• Eiichiro Yoshimoto,
• Bing Xiaohuan,
• Masato Morita,
• Motohiro Yasui,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233

• fluoroalkylated amines 15 with high optical purity could be easily prepared through [1,3]-proton shift reactions of optically active imines 14 which in turn were readily synthesized by condensation of various perfluoroalkyl ketones with optically active (R)-1-phenylethylamine (Scheme 2a) [25][26][27][28][29][30

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• additional nitrogen atoms in compounds 4 leads to the fact that the other tautomeric form becomes more favorable. A proposed mechanism of the investigated recyclization is presented in Scheme 4. Initially, imidazolide A is formed via condensation of the starting amide 3 with CDI. Then, intermediate A

• refluxing EtOH allowed us to obtain substituted enehydrazine 7 (Scheme 5a). The similar condensation with amine 8 led to enamine derivative 9 (Scheme 5b). Based on the data of X-ray analysis compound 7 has the same configuration of double and hydrogen bonds as in the case of starting tetronic acids 4