Electrochemical reduction of unsaturated carbon–carbon bonds via 3d transition-metal catalysis

• Geon Kang,
• Minki Jeon,
• Pooja Kumari Jat,
• Cheoljae Kim and
• Isaac Choi

Beilstein J. Org. Chem. 2026, 22, 955–981, doi:10.3762/bjoc.22.75

• group reported a voltage-controlled tandem electrocatalytic Z-selective semihydrogenation, in which cobaltocene operates as a cobalt redox mediator 3 in concert with a cobalt catalyst 9 (Scheme 4A) [97]. This strategy enables the selective hydrogenation of activated alkynes to cis-alkenes while

Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• that the reaction proceeded via a copper–pyrazolate (copper–amido) catalytic cycle [56]. The active copper–amido species I initially coordinated to the cyclopropene to form a π-complex II, followed by cis-aminocupration across the strained alkene, generating a cyclopropylcopper intermediate III

• hydroamination to furnish the enantioenriched indoline products 48 in moderate-to-good yields, with up to 89% ee. Mechanistic studies have suggested that the reaction proceeds via the cis-aminocupration pathway, in which a nitrogen nucleophile and copper(II) are added across the alkene to form the organocopper

Cascade transformation of 2-(diazoacetyl)-2H-azirines to 2-aroyl-3-hydroxy-1H-pyrroles via condensation with aromatic aldehydes

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2026, 22, 897–904, doi:10.3762/bjoc.22.70

• , to our knowledge, no derivative of trans-2-oxa-7-azabicyclo[4.1.0]heptane has been prepared [25][26]. According to our DFT calculations, trans-2-oxa-7-azabicyclo[4.1.0]heptane has a 42.6 kcal/mol higher Gibbs energy than the cis isomer, and the introduction of two sp2-hybridized carbons, as in

The trans-influence in gold chemistry from a catalytic perspective

• Manfred Bochmann

Beilstein J. Org. Chem. 2026, 22, 838–856, doi:10.3762/bjoc.22.66

• -planar geometries there is always also the influence of two cis-ligands. Melpolder and Burmeister used solution infrared spectroscopy to determine the ratio of N-bonded and S-bonded thiocyanate ligands in LAuSCN/NCS as a function of L. As expected, ligands L with a strong trans-influence, such as

• σ-MOs is reduced by SO mixing with the Au(dπ)-based MOs. Further computational exploration of the trans-influence of various ligands L was conducted on three series of model complexes: trans-[HAu(C6H5)2L]q, cis-[HAu(C^C)L], and [HAu(C^N)L]q+1. Ligands L in trans position have by far the largest

• < C6F5− ≈ PH3 < C6H5− < CH3− < H− < SiH3−. Ligands in cis position exert a weaker influence, spanning about 6 ppm but with a trend in the opposite direction, with the weakest σ-donors, as well as the strongest π-acceptors, exhibiting the highest deshielding, resulting in the most positive 1H hydride

Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against Klebsiella pneumoniae ST512

• Shuo Zhang,
• Ondřej Daněk and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2026, 22, 821–827, doi:10.3762/bjoc.22.64

• . Key synthetic challenges including the stereoselective construction of the 1,2-cis glycosidic linkage on the galacturonic acid core and the inherently low reactivity of elongated oligosaccharide intermediates were addressed employing orthogonally protected building blocks. The resulting library of

• repeating unit {3)-[α-ʟ-Rhap-(1→4)]-α-ᴅ-GalpA-(1→2)-α-ʟ-Rhap-(1→2)-α-ʟ-Rhap-(1→2)-α-ʟ-Rhap-(1→3)-β-ᴅ-Galp-(1→}n (Figure 1) [13]. The chemical synthesis of this molecule is challenging due to the stereoselective formation of the 1,2-cis glycosidic linkage on the galacturonic acid core. In addition, the

• furnished tetrasaccharide 15. Subsequently, donor 3 was coupled with compound 15 under NIS/TfOH promotion to yield pentasaccharide 16 in 89% yield. The stereoselective construction of the 1,2-cis linkage was directed by the bulky 4,6-O-silylidene protecting group of 3. Treatment with HF·pyridine

Synthesis and biological evaluation of new brassinosteroid analogs with C-22 benzoate function

• María Núñez,
• Camila Escobar,
• Mario Párraga,
• Mauricio Soto,
• Luis Espinoza-Catalán,
• Katy Díaz and
• Andrés F. Olea

Beilstein J. Org. Chem. 2026, 22, 753–762, doi:10.3762/bjoc.22.57

• HSQC NMR and 1H,13C HMBC NMR spectra data, respectively (Figures S35 and S36, Supporting Information File 1). Previous studies have shown that Sharpless dihydroxylation of 2,3-steroidal alkenes with OsO4/DHQD-CLB system, leads to formation of "cis" glycols with C-2(R) and C-3(S) stereochemistry in the

Rongalite addition to dienones: diastereoselectivity in cyclic sulfone synthesis; stereochemical rationalization and prospects as a general conjugate nucleophile

• Melina Goga,
• Hao Zong,
• James Franco,
• Jazmine Prana,
• Rudolph Michel,
• Antonia Muro,
• Elana Rubin,
• Janet Brenya,
• Henk Eshuis and
• Magnus W. P. Bebbington

Beilstein J. Org. Chem. 2026, 22, 742–752, doi:10.3762/bjoc.22.56

• crude 1H NMR spectrum (Supporting Information File 1). We thus used computation to model the cyclization to give products trans-12a and cis-12b, as this substrate appeared to represent a limiting case for both reaction diastereoselectivity and steric tolerance. Given that the reaction takes place in a

• work, by which we were able to locate transition states for reactions to give trans-12a and the unobserved cis-12b (Figure 4). The activation energy difference to reach TS-12a, leading to 12a and TS-12b, leading to 12b was found to be a significant 4.7 kcal/mol in favor of TS-12a (see Supporting

• reaction of this type. What follows is an examination of the transition state structures leading to the trans and cis-isomers 12a and 12b; although the transition states leading to 1a and 1b may differ slightly in energy, they are very similar in appearance to those for 12a and 12b. Examination of the

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

• activated alkenes was proposed. The authors demonstrated the potential for cycloaddition of silylimines containing a pyridine substituent with various dipolarophiles (Scheme 33). In all cases, the cycloaddition reactions proceeded with very high diastereoselectivity (trans/cis >95:<5), providing the trans

Synthesis of depressin, cryptomeridiol and 4-epi-cryptomeridiol enabled by a terpenoid chiral pool-producing platform

• Yao Kong,
• Tao Wang,
• Chen Wang,
• Pengcheng Zhang,
• Yuanning Liu,
• Kaibiao Wang,
• Fen Liu,
• Hongli Jia and
• Zhengren Xu

Beilstein J. Org. Chem. 2026, 22, 683–690, doi:10.3762/bjoc.22.53

• ). Depressin (1) was isolated from the soft coral Simularia depressa collected from Hainan Province of China [13]. Its structure contains the typical bicyclo[12.1.0]pentadecane casbane diterpenoid skeleton with a cis-disubstituted cyclopropane unit, and a keto group at C5, which is the most frequently oxidized

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• and can be potentially used at a later stage. A strong emphasis is on molecular photoswitches (photochromic molecules) that upon irradiation undergo cis/trans isomerization, intramolecular photocycloaddition, or an electrocyclic reaction. In addition, several articles describe absorption tuning by

• between trans and cis isomers, represent another class of photoswitches, which were reviewed as mostophores in a Perspective by Wang, Wu, and co-workers [8]. Besides MOST systems, molecular photoswitches are interesting for a variety of potential applications when incorporated as photoresponsive units in

Computational prediction of C–H hydricities and their use in predicting the regioselectivity of electron-rich C–H functionalisation reactions

• Rasmus M. Borup,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2026, 22, 603–610, doi:10.3762/bjoc.22.46

• -catalysed C–H carbamoylation of the cis-fused azabicyclo[4.3.0]nonane derivative 9, and Overman and Tomasi [46] reported the Cu(II) salt-catalysed addition of a N-tosyl group to the C–C double bond in compound 10 in conjunction with an H-abstraction, to form a new C–C double bond. In all three cases, the

Experimental and DFT studies on the regioselective methanolysis of 5-azido-9-oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers

• İlknur Polat,
• Selçuk Eşsiz and
• Emine Salamci

Beilstein J. Org. Chem. 2026, 22, 547–556, doi:10.3762/bjoc.22.40

• -oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers starting from cis,cis-1,5-cyclooctadiene. Results and Discussion For the synthesis of the hitherto unknown key compound 8-azidocyclooct-4-en-1-yl 4-nitrobenzoate (8), we commenced by obtaining the known 5,6-epoxycyclooctene (6), which was prepared by

• epoxidation of cis,cis-1,5-cyclooctadiene (5) with m-CPBA [21][22]. Subsequently, the 5,6-epoxycyclooctene (6) was reacted with NaN3 and NH4Cl in EtOH/H2O to give azidol 7 in 92% yield [23] (Scheme 1). Azidol 7 was then converted into the corresponding azido nitrobenzoate 8 with p-nitrobenzoyl chloride (p-NBC

• -ray analysis (Figure 2) [25]. X-ray analysis of azido compound 10 confirmed the trans configuration of the azide group with chloride and the cis configuration with the acetate. Our suggested mechanism for the ring-opening of the epoxides 9 with HCl(g) in MeOH proceeded as described in Scheme 3. As

Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• hydrogenated pyran rings of 4 can only be linked cis, the two possible enantiomers of 4 have the following configuration: (6aR,9S,10aS,10bR) or (6aS,9R,10aR,10bS). Due to the finding, that the isolated compound showed no optical rotation, it exists as a racemate. A stereo model of 4 provided important

A facile and practical method for the synthesis of trans-(±)-taxifolin and its derivatives via Darzens reaction

• Bo Peng,
• Panpan Yang,
• Maaz Khan,
• Xiaotong Lin,
• Jiang Wu,
• Peng Fu and
• Qingqing Wu

Beilstein J. Org. Chem. 2026, 22, 443–450, doi:10.3762/bjoc.22.31

• transformation from dietary food to multifunctional medications in the near future. Taxifolin is a chiral compound with two stereocenters and exists as trans or cis isomers. It is commonly referred to as the trans dextral form (trans-(+)-taxifolin), which has higher bioactivity than its levorotatory enantiomer

• . The stereochemical outcome of the Darzens reaction may produce the α,β-epoxycarbonyl products with either the substituents on the same side or opposite side of the epoxy functionality, i.e., as cis/trans isomers. In this work, the α,β-epoxycarbonyl product contains bulky multiple-substituted benzene

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• diastereoselective hydrogenation of symmetrical 2,5-DKP (2,5-dipiperazinone) 67 using a rhodium complex (Scheme 8) [63]. The saturated pentacyclic compound 68 was obtained in high yield and excellent diastereoselectivity. The hydrogen atoms in the final product were all arranged in cis configuration. Key features of

• catalyst in the presence of perchloric acid to obtain (−)-decahydrotabersonine, a product with a completely reduced aromatic ring (Scheme 13) [79]. Through the structural characterization of the product, the authors found that the hydrogenation was highly stereoselective, yielding only cis-hydrogenated

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

• reported the synthesis of conjugated alkenyl chloride 183 by chlorination of cis-diol 181 and subsequent elimination of product 182 with KOH (Scheme 31) [130]. Schlosser reported that treatment of 1,2-dichloroalkanes with sodium or potassium hydroxide in dimethoxyethane effected selective elimination

• phosphonium salt 342 is commercially available (CAS: 5293-84-5) and is frequently employed for the formation of alkenyl chlorides (e.g., Scheme 60C) [196]. It is noteworthy that a highly cis-selective variant, necessitating a sophisticated phosphonium salt, was reported by Schlosser in 1993 [197]. In 2006

Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones

• Svetlana O. Kushch,
• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess,
• Pavel A. Slepukhin,
• Alexandrina S. Volobueva,
• Vladimir V. Zarubaev and
• Victor I. Saloutin

Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209

• composition of the products, increasing the content of the trans,cis-form 4atc to 20%. The use of 1,4-dioxane with acetic acid catalysis at different molar ratios (Table 1, entries 7, 8) led to the formation of a large fraction of unidentified by-products (42–61%), whereas the base catalysis with

• %) (Table 1, entry 10), with the formation of the cis,cis-bicycle 4acc as the predominant product (28%), while the proportion of hexahydrooxazolopyridones 5 was minimal (10%) compared to all other conditions. The highest content of hexahydrooxazolo[3,2-a]pyridin-5-one 5a was observed at room temperature in

• octahydrocyclopenta[b]oxazolo[3,2-a]pyridin-5-ones in the reactions of 3-oxo ester 1 and cycloketones with amino alcohols [26]. However, these attempts turned out to be unsuccessful because of the increased occurrence of side processes (56%); however, an increase in the proportion of the cis,trans

Recent advancements in the synthesis of Veratrum alkaloids

• Morwenna Mögel,
• David Berger and
• Philipp Heretsch

Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206

• cevanine-type alkaloids has been reported [13][38][39][40][41][42]. The common hexacyclic framework is often highly oxidized and the hydroxy groups are further functionalized as esters of various carboxylic acids. Apart from the hydroxylation pattern, structural diversity is also imparted through a cis- or

• in refluxing toluene, giving 99 in 88% yield as a single diastereomer. Due to steric hindrance, dienophile 98 would approach the more accessible face of diene 97, i.e., cis to C8–H. Furthermore, exclusive endo-addition was observed because exo-addition would lead to severe interference between the

• TBSO-substituent on the dienophile and the diene. As a result of such endo-addition, the benzyloxy group in the diene and the acylpyridine of the dienophile are oriented cis to each other in adduct 99. Next up was the formation of the C20–OH by addition of MeMgBr to the ketone 99, which initially gave

Chemoenzymatic synthesis of the cardenolide rhodexin A and its aglycone sarmentogenin

• Fuzhen Song,
• Mengmeng Zheng,
• Dongkai Wang,
• Xudong Qu and
• Qianghui Zhou

Beilstein J. Org. Chem. 2025, 21, 2637–2644, doi:10.3762/bjoc.21.204

• – sarmentogenin and ʟ-rhamnose connected by the C3–O bond. In the steroidal skeleton, both the A/B and C/D rings are cis fused, which is different from common steroids. Besides, the steroidal skeleton is moderately oxidized at the C3, C11, and C14 positions. The introduction of the hydroxy groups and the

• C14 β-OH group. The revised synthetic route is described in Scheme 2. At first, 4 was subjected to a Pd/C-catalyzed hydrogenation to afford the desired A/B-cis fused intermediate 7 along with its C5 epimer as a 2:1 separable mixture in a quantitative yield. By treating 7 with the Bestmann ylide

Efficient solid-phase synthesis and structural characterization of segetalins A–H, J and K

• Liangyu Liu,
• Wanqiu Lu,
• Quanping Guo and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2025, 21, 2612–2617, doi:10.3762/bjoc.21.202

• ) and G (7) using a pseudoprolinic acid strategy to induce cis-amide bond formation, followed by desulfurization [19]. Despite achieving cyclization, this route involves intricate procedures, expensive starting materials, and has limited applicability to other segetalins. Given the limitations of

Recent advances in total synthesis of illisimonin A

• Juan Huang and
• Ming Yang

Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199

• directly, the team adopted a strategy involving rearrangement from the more accessible cis-pentalene isomer. They first assembled the cis-pentalene core through an elegant intramolecular Diels–Alder (IMDA) reaction. Subsequently, the conversion from cis to trans-pentalene was achieved via a semipinacol

• , obtained as a 1.7:1 mixture of diastereomers after protection of one of the carbonyl groups in 19 as enol ether with BOMCl. A silyl-tethered intramolecular Diels–Alder reaction of the in situ generated 22 constructed the tricyclo[5.2.1.01,5]decane core bearing a cis-pentalene unit, yielding compound 23

• rearrangement of 28 enabled the rearrangement of cis-pentalene to trans-pentalene, delivering intermediate 29, which possesses the same carbon skeleton as the natural product. Further oxidation of the primary alcohol to a carboxylic acid, accompanied by TBS deprotection, afforded hemiketal 30. Finally, a White

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• three contiguous stereogenic centers (Scheme 1A). The pyran ring was constructed by a RCM reaction [16]. Subsequent functionalization of the alkene to install the 1,2-cis-hydroxy amine required 6 steps from the sterically more demanding side. In continuing our recent interest in accessing unusual

• intermediate 5 will be converted into the final target after installation of the urea and uracil motifs. Accordingly, a nitrone-based latent functionality approach [28] would be tunable from fully substituted tetrahydrofuran-derived nitrone 7. The cis-1,2-hydroxy amine could be derived from oxazoline 6 through

• malayamycin A and other related uracil nucleosides via a dipolar cycloaddition. The latent functionality strategy employing oxazoline to reveal the cis-1,2-hydroxyamine moiety proves to be feasible, circumventing the lengthy route for alkene functionalization required in previous syntheses. Although the

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• construction of the tetracyclic core of Aspidosperma alkaloids. Our method involves an Ir-catalyzed PET reaction of K for the stereoselective formation of the cis-configured BC bicyclic core with an all-carbon quaternary center [25][26]. Computational studies suggest that the observed tandem PET reaction of K

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• given in Table 1. Looking at the obtained conformations (Figure 5B), one can find that the same π–π interactions are present in the α-galactoside structures as in their β-isomers. However, there is a possibility of another interaction. This is the repulsion between the cis-oriented O-1 and O-2 atoms in

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• C7, forming synthon 60. Destruction of this tetrahedral intermediate with migration of the aryl group promoted the formation of intermediate 61, decarboxylation of which led to the cis-substituted product 62. The resulting ketone 62 was the key synthon in the synthesis of (−)-taiwaniaquinone H (11

• Dotson et al. [84] for cis/trans salts 159 (Scheme 30). The authors noted that photochemical experiments carried out in benzene solutions with benzylic esters cis-159 or trans-159 gave complex product mixtures. To achieve higher conversion, a photochemical reaction was carried out in the crystalline

• in the stabilization of cationic reaction intermediates [91][92]. Yokoshima and co-workers [93][94] developed an elegant approach to the total synthesis of the alkaloid huperzine Q (206) in racemic form (Scheme 37). In the process of synthesis, a cis-hydrindane core was prepared from the known