The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products

• Dong-Xing Tan and
• Fu-She Han

Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164

• -catalyzed intermolecular Diels–Alder reaction of 106 with methacrolein 107 afforded the common intermediate 108 in high yield. Sequential Grignard reagent addition and acid-promoted ethoxy elimination provided the separable planar diene 109 (dr = 1:1), which underwent a Mn-catalyzed HAT hydrogenation to

• -mediated condensation with 112 accomplished the total synthesis of (−)-platensilin (23). Based on the aforementioned successful work, the authors focused on the synthesis of (−)-platencin (24) and (−)-platensimycin (25) (Scheme 11) [82]. Accordingly, Wittig reaction of 108 followed by 1,4-elimination and

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• underwent dehydroxylation protocol involving base-promoted mesylate elimination and catalytic hydrogenation reactions, providing 31a. Reduction of lactam and ester in one pot with LiAlH4 and acid-promoted hydrolysis of ketal protection to ketone furnished 32a. Finally, oxidation of the primary alcohol to

α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• sufficiently electrophilic carbonyl carbon atom with the elimination of triphenylphosphine oxide via the aza-Wittig reaction. It should be noted that the best method for the isolation of quinoxalinones 9 was column chromatography using an elution gradient of hexane/ethyl acetate 3:1 to hexane/ethyl acetate 1:2

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• ]. The experimental studies on the thermal denitrogenation of diazabicyclo[2.1.1]hep-2-ene (DBH, 1) indicate that both the parent compound and its derivatives undergo a concerted elimination of N2 and the inverted product (exo-2) is preferentially formed [55][56]. Deuterium labeling of DBH was employed

• preference for inversion across several derivatives of 1 [77][78]. These studies suggest that the thermal denitrogenation of diazabicyclo[2.1.1]hep-2-ene undergoes a concerted mechanism of elimination of nitrogen, while the photochemical reaction proceeds via a stepwise mechanism. Quantum mechanical

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• likely formed via the allylic cation intermediate Int-1 (Scheme 2), from where on two competing mechanistic pathways are possible. Deprotonation of the β-H and reductive elimination affords diene 10. Alternatively, an intramolecular cyclization leads to silylindenes 11. We were interested to see whether

• an internal nucleophile (O-, N-) and reductive elimination affords the arylated product 8 and regenerates the Cu(I) catalyst. The added base (B:) traps the H+, generated in this catalytic cycle. In the case of tert-butyl esters (7: R = COOt-Bu) an equivalent of isobutylene gas is released as a side

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• additional photocatalyst. Moreover, under the same photocatalyst-free conditions, UV-A-light-mediated reduction could be achieved using triethylsilane as the only reductant with subsequent desilylation and NHC elimination with fluoride delivering the corresponding aldehyde product. Keywords: carbenes

• intermediate A (Figure 1a), in which the formerly electrophilic carbonyl carbon reacts as a nucleophilic center. In this way, the traditional reactivity profile of the carbonyl group is transiently inverted, and unconventional product classes are generated. Alternatively, addition/elimination of the NHC to a

• presence of this intermediate reduction product in the reaction mixture. Compound 3 is likely formed in a two-stage process involving initial reduction of the carbonyl group followed by addition/elimination of the resulting alkoxide into a second equivalent of the acylazolium salt 1; a sequence which also

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• CPA-catalyzed cyclization of INT-E through the dual hydrogen bonding activation transition state TS-1 afforded the eight-membered heterocycle INT-F with a stereogenic center. Through the elimination of aniline 73, the saddle-shaped dibenzo[1,5]diazocine 72 was produced via a central-to-inherent

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

Influence of the cation in hypophosphite-mediated catalyst-free reductive amination

• Natalia Lebedeva,
• Fedor Kliuev,
• Olesya Zvereva,
• Klim Biriukov,
• Evgeniya Podyacheva,
• Maria Godovikova,
• Oleg I. Afanasyev and
• Denis Chusov

Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130

• reduction of iminium cation (ΔEa = 27.6 kcal/mol TS4→5) had a lower barrier than the elimination of water from the protonated hemiaminal 30.3 vs 43.8 kcal/mol, respectively, which meant that the rate-determining step in the reductive amination of dimethylamine with benzaldehyde was the formation of iminium

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• were formed through a reaction sequence involving double isocyanide insertion, reductive elimination, and acyl transfer. To be noted, the introduction of a substituent at the ortho-position of the isocyanide group in 16 caused a significant drop in the enantioselectivity (e.g., 17b). Besides, when

• reductive elimination to afford INT-IV. Finally, migration of the Piv group from O to N gave the product 17a. Moreover, the Pd-catalyzed isocyanide insertion approach has been successfully extended to the generation of helical chirality [31]. As shown in Scheme 4a, phenyl diisocyanides 21 or 22 underwent

• with both axial and central chirality, followed by 2) ring-strain and aromatization-driven elimination, which elucidating the observed unusual torsional strain-independent reactivity. In addition, products bearing a tert-butyl ester group were smoothly converted into structurally novel axially chiral

3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles

• Julia I. Pavlenko,
• Pavel A. Sakharov,
• Anastasiya V. Agafonova,
• Derenik A. Isadzhanyan,
• Alexander F. Khlebnikov and
• Mikhail S. Novikov

Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123

• to the azirine C=N bond, followed by cyclization and the aziridine ring opening into the [3 + 2] cycloaddition product 5 (Scheme 3). It is noteworthy that the annulation proceeds via the azirine N‒C3 bond cleavage. Elimination of the methoxycarbonyl group most likely occurs under the action of

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• ,d, respectively, as the expected reactive intermediates after N2 elimination from 2c and 2d. Trapping of transient thiocarbonyl S-methanides 1 with enolizable 1-substituted 5-mercapto-1H-tetrazoles 4 Adamantanethione S-methanide (1a) is considered as a prominent representative of the ‘sulfur

Copper catalysis: a constantly evolving field

• Elena Fernández and
• Jaesook Yun

Beilstein J. Org. Chem. 2025, 21, 1477–1479, doi:10.3762/bjoc.21.109

• . In their contribution, Son et al. focus on transformations via the formation of copper nitrenoids, particularly amidations via oxidative insertion to N–O bonds and reductive elimination, and a small number of other reactions. The final Review by Cho, Lee, and co-workers is useful for the scientific

Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles

• Vladimir G. Ilkin,
• Pavel S. Silaichev,
• Valeriy O. Filimonov,
• Tetyana V. Beryozkina,
• Margarita D. Likhacheva,
• Pavel A. Slepukhin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104

• analogy with an aza-Michael reaction first with the addition of iminoiodinane accompanied with reorganization of double bonds including attack of the negatively charged sulfur atom on nitrogen with subsequent elimination of iodobenzene as good leaving group. The diversity of the structure of the target

N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B

• Joy E. Rajakulendran,
• Emmanuel Tope Oluwabusola,
• Michela Cerone,
• Terry K. Smith,
• Olusoji O. Adebisi,
• Adefolalu Adedotun,
• Gagan Preet,
• Sylvia Soldatou,
• Hai Deng,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103

• condensation product, compound 2. Compound 1 is proposed to further undergo a dehydration reaction by the elimination of the α-proton and β-hydroxy group of the threonine residue to form compound 3. Compound 4 is a product of methylation of 3 carboxyl functionality (see Figure 4). These compounds are possibly

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• intramolecular E2 elimination. Finally, the importance and power of the intramolecular Williamson etherification has also been demonstrated by the kilogram-scale synthesis of oxetane intermediate 41, which is a key intermediate in the preparation of the previously mentioned IDO1 inhibitor 2 (Scheme 9) [16

• extended enolate 96 to the ketone, cyclisation via addition/elimination and base-catalysed epimerisation towards the thermodynamically more stable diastereomer. In 2019, Nair and co-workers showed that this formal cycloaddition can also be performed with 1,2-dicarbonyls as electrophiles and under an

• halogens, nitriles, alkenes and heteroaryls. On the other hand, this methodology suffers from relatively low diastereoselectivity as the dr lies between 1:1 and 2:1. DFT calculations suggested the reaction proceeds through nitrogen elimination, oxonium ylide 119 formation, homolytic cleavage and radical

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

• to generate σ-alkylpalladium(II) intermediate II, which is trapped by the α-carbonylalkyl radical A in the presence of Ag0 species [18]. Finally, reductive elimination occurs to yield the desired product. Inspired by the above work, a novel, general silver-catalyzed oxidative alkyletherification of

• elimination or single-electron oxidation and deprotonation, yielding the final oxindole products 81 and regenerating the Pd(0) catalyst I. In the same year, Zhang’s group developed a novel visible-light-induced palladium-catalyzed intermolecular radical cascade cyclization of N-arylacrylamides with

Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents

• Julius Krenzer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97

• 1 suggests starting from aroyl chlorides 2 and 2-methyl-N-benzylbenzothiazolium salts 3 by a condensation transform (Scheme 1). The condensation essentially represents an addition–elimination sequence that starts with the nucleophilic S,N-ketene acetal 4, in situ generated from substrate 3 by

• deprotonation, followed by chloride elimination/neutralization from the zwitterionic tetrahedral intermediate 5 to give the target molecule 1. The standard protocol for the synthesis of (hetero)aroyl-S,N-ketene acetals 8 from (hetero)aroyl chlorides 6 and 2-methylbenzothiazolium salts 7 employs a twofold excess

• presumed byproducts in the addition–elimination sequence in the presence of an excess of ethanol as a cosolvent are the ethyl ester formed by Einhorn acylation [7] of the acid chloride under the standard conditions and deep colored polar byproducts (according to TLC detection) that arise from self

Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups

• Julius Seumer,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94

• and carboxylic acid. The palladacycle intermediate can undergo further (coupling) reactions and form a variety of products via reductive elimination. In previous studies, the rate- and regioselectivity-controlling step was identified as the formation of the palladacycle [5][6][7]. The regioselectivity

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

• intermediate 85 followed by reductive elimination with tertiary amine to give intermediate 86. The utilization of earth-abundant transition metals for O/N-acylation has emerged due to their low cost. For instance, Son and co-workers (2023) utilized a more cost-efficient Cu salt to access N-acyliminophosphorane

• 89 from the corresponding dioxazolone 88 in excellent yields via reductive elimination from intermediate 90 (Scheme 26) [62]. Hu and co-workers (2019) also employed a Cu salt (Cu(OTf)2) to synthesize N-difluoroethylimide 91 from cinnamic acid (7) and tert-butyl nitrite (TBN) in good yield via

• been successfully done for this method. Similarly, Hou and co-workers (2022) also used CO2 to carry out an auto-tandem Cu-catalyzed carboxylation of styrenes via β-hydride elimination (208) (Scheme 60B) [104]. Impressively, several natural product-like compounds (e.g., 207) were successfully prepared

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

• photocyclization. This transformation was carried out using a high-pressure mercury vapor lamp to afford benzazepine 22, completing the construction of the pentacyclic framework of the natural product. Subsequent functional group manipulations, including the Chugaev elimination of the hydroxy group on the

• divergent total synthesis of several Cephalotaxus alkaloids. The α-hydroxylation of cyclopentanone, followed by amide reduction and methanol elimination in one-pot, produced (−)-cephalotaxine in 9 steps. Alternatively, Riley SeO2 oxidation of 31, benzylic bromination/hydrolyzation, facial selective ketone

• attack of the electron-rich arene on the acyliminium ion occurs from the Si-face. This stereochemical outcome is attributed to the steric discrepancy of the phenyl or tert-butyl group and the hydroxy group. The resulting tricyclic products could be further elaborated by elimination or amide reduction to

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• alkene side product, presumably arising from mesylate elimination (Table 4, entry 4). In general, the functional group tolerance of the reaction was good, and aryl halogens, aryl CF3 moieties, and benzyl ethers were fully compatible (Table 4, entries 7 and 8). Where applicable, stereoarrays could be

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

• H2O under neutral conditions merely resulted in decomposition (Table 1, entry 10). To our delight, photoirradiation of the corresponding methyl ether 31 at 254 nm in the presence of AcOH at 20 °C led to a smooth cyclization, followed by spontaneous elimination, which produced the desired 10 as the

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

• , tetrabutylammonium iodide (TBAI), and water significantly accelerated aryne generation, thereby increasing its local concentration. This favored aryne coordination to the palladium center, followed by CO insertion and reductive elimination to furnish phenanthridinones. In contrast, when dppm was introduced

• preferentially occupied the palladium coordination site. Sequential insertion of CO and aryne, followed by reductive elimination, culminated in acridone formation. This ligand-dependent mechanistic dichotomy underscores the critical interplay between aryne availability, steric modulation, and electronic effects

• elimination yields the benzofuro[3,2-c]quinolinone product 9 along with a Pd(0) species, which is reoxidized to Pd(II) by BQ (benzoquinone). When the ligand is switched to the sterically bulky and electron-rich dppm, the chemoselectivity is reversed: the palladium center now preferentially coordinates with

Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes

• Patricia Gómez-Roibás,
• Andrea Chaves-Pouso and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71

• . Finally, the new enolate E evolves through intramolecular proton abstraction and elimination of boryllithium [20][21]. The formation of side product 3 observed when dichloromethane was used as a solvent could be explained by protonation of intermediate A, followed by transmetalation of the resulting