Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• enantioselectivity. First, the reaction of ketimine ester 33 and 2,3-dimethylhydroquinone at 10 °C provided the chiral 1,4-addition product 35 via dynamic kinetic asymmetric transformation (DyKAT). Conversely, when the reaction was performed at −10 °C, the reaction pathway switched from DyKAT to kinetic resolution

• (KR) of the racemic ketimine ester, providing the same chiral product 35 with recovered enantioenriched starting material. Additionally, when a 1-naphthyl ester was used instead of a methyl ester at −10 °C, 1,4-addition followed by intramolecular tandem annulation generated the corresponding chiral

• copper-coordinated azomethine ylide 39. Subsequently, the chiral products 35–37 are produced through the reaction between the metalated azomethine ylide 39 and the quinone intermediate 38. The reaction pathway, either 1,4-addition or 1,6-addition, depends on the structure of the hydroquinone 34. The less

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

• -catalysis recently led to an array of intriguing transformations. Axially chiral styrenes 26 were assembled via the NHC-catalyzed reaction of propargylic aldehydes 25, sulfinic acids, and phenols [28]. The crucial step of this transformation is the 1,4-addition of the sulfinic anion to the triple bond of

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• authors proposed a possible mechanism for the reaction which is depicted in Scheme 20. The chiral phosphoric acid activates both the azoalkene acting as a Brønsted acid and the indole acting as a Lewis base promoting a Friedel–Crafts-type 1,4-addition of the indole to the azoalkene. In this manner, a

• enantioselectivities (92–96% ee). The proposed reaction pathway is depicted in Scheme 30, the phosphoric acid simultaneously activates the azadiene through hydrogen bonding and the azlactone which is converted to its enol form establishing hydrogen bonding with the phosphoryl group. Next, the 1,4-addition of the

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• mesoporous material. Photoinduced RAFT polymerisation of n-butyl acrylate (19) catalysed by silica nanoparticle-supported eosin Y 21, which could be recycled over five reaction cycles. Pressure and temperature dependence of the 1,4-addition of propanal to trans-β-nitrostyrene under continuous flow conditions

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• 10.3762/bjoc.20.136 Abstract The enantioselective 1,4-addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones catalyzed by a cinchona alkaloid-derived primary amine–Brønsted acid composite is reported. Both enantiomers of the anticipated pyrazole derivatives were obtained in good to excellent

• [10][11][12][13][14][15][16][17][18][19][20][21]. Among the developed organocatalyzed enantioselective 1,4-addition reactions of pyrazolin-5-ones, the catalytic asymmetric reactions of pyrazolin-5-ones with α,β-unsaturated ketones are comparatively less studied. In 2009, Zhao’s group were the first

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• -dicarboxylate (3) with 2,3-unsubstituted parent chromone (9a) afforded benzocoumarine 17 in 56% yield (Scheme 3) [32]. The formation of the product can be explained by 1,4-addition of 3 to the chromone to give intermediate A and ring cleavage to give intermediate B. Subsequent Knoevenagel reaction by attack of

• triethylamine in methanol afforded benzocoumarines 18a–ac (Scheme 4) [33][34]. The formation of the product, which was obtained in a two-step one-pot reaction, can be explained by a mechanism similar to the one discussed for the formation of 17. 1,4-Addition gave intermediate D which was isolated, but used in

• ) [32]. The formation of the products can be explained by Michael reaction (1,4-addition) of 3 to the chromone and ring cleavage to give intermediate G. Subsequent Knoevenagel reaction by attack of the methylene carbon to the aldehyde resulted in the formation of the final products. The regioselective

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• latter undergoes addition–elimination reaction with another molecule of o-anisidine to give 2-(phenylamino)cyclohexa-2,5-diene-1,4-dione. The third unit of o-anisidine is added to the quinone via 1,4-addition, followed by oxidation of the 1,4-dihydroxy compound to give 2,5-bis((2-methoxyphenyl)amino

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• -substituted dienes 2b and 2c were suitable for this MCR, affording the 1,4-addition products 4l and 4m albeit with moderate regioselectivity (1,4-/1,2-addition = 2:1). To our delight, the reactions with 2,3-disubstituted diene 2d and 1,4-disubstituted diene 2e also readily provided products 4n and 4o. In the

• , the corresponding 1,2-addition products 4p–t were formed with high selectivity (E/Z > 20:1, 1,2-/1,4-addition >20:1), presumably due to steric hindrance by the phenyl group. Furthermore, the 1,3-diene bearing a 1-furan group with smaller steric hindrance afforded product 4u with moderate

• chemoselectivity (1,2-/1,4-addition = 4:1). Diazo esters suitable for this transformation were examined next. The MCRs with diazo substrates equipped with different substitution patterns were accommodated under the mild photocatalytic conditions to generate the desired 1,4-addition products in moderate to good

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• carbonyl compounds 168 can be achieved with N-thiophthalimides 14 and diaryl disulfides 47, respectively (Scheme 73) [104]. They remarked that the presence of B2pin2 was essential in the coupling reaction of disulfides with α,β-unsaturated carbonyl compounds 168. The sulfenylation involved a 1,4-addition

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

• that α-(aminomethyl)acrylates are suitable acceptors for 1,4-additions of dialkylzincs in aerobic conditions. The air-promoted radical–polar crossover process involves the 1,4-addition of an alkyl radical followed by homolytic substitution at the zinc atom of dialkylzinc. Coordination of the nitrogen

• 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

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• Indonesian sponge Haliclona sp. [108]. Their synthesis takes advantage of the same tandem procedure that gives β-ketoester 219. The asymmetric conjugate 1,4-addition and subsequent acylation provided good stereocontrol and the authors could revise the thus far incorrectly assigned configuration of the target

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• be shifted to the 1,4-addition producing a cyclopentene product leading to the conclusion that the substitution pattern on the boronate ester played a significant role in the selectivity between 1,6-addition and 1,4-addition. The mechanism proposed by the authors initially begins in the same manner

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• -pyrone by desymmetrization of α,α’-dimethoxy-γ-pyrone 2 through the addition of hindered nucleophiles to construct the vicinal quaternary carbon. In a subsequent and potentially enantioselective desymmetrization step, compound 5 would be converted into trichiachiapyrone B by 1,4-addition of the side

• investigation, it is mostly restricted to substrates bearing a tertiary alkoxy group [34]. Few examples of this intermolecular strategy actually involve substrates containing a quaternary carbon and the formation of a C–C bond [35][36]. Of note was the report of Takemoto and Iwata describing the 1,4-addition of

• the steric hindrance of the electrophile and potentially facilitate the 1,4-addition, 2,5-cyclohexadienone 14, deprived of a methyl group, was prepared and tested but the reactivity was not significantly improved compared to 5. Both compounds appeared thus mostly reluctant to 1,4-addition and, when it

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• cinnamaldehyde molecule 3, enhancing the reactivity. The reaction between the enamine and the cinnamaldehyde derivative 3 advances via two steps: Initially, the enamine attacks the cinnamaldehyde compound 3 at the double bond and undergoes 1,4-addition to give intermediate B. The enol form is readily converted

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• , with moderate to excellent enantioselectivity followed by two decarboxylations (Scheme 21). Huang’s group has used azadienes to perform an enantioselective 1,4-addition to afford benzofuran-fused six-membered heterocycles with a squaramide catalyst [56]. Based on their previous work, the authors

• reported an enantioselective 1,4-addition of azadienes 71 to 3-homoacyl coumarins 70 to achieve benzofuran coumarin derivatives 72 [57]. It was possible to obtain good to excellent diastereo- and enantioselectivities by using a low amount of the catalyst, besides the high yield of the reaction. The best

• -hydroxycoumarins (1) and aromatic imines 63 promoted by cupreine (65). Asymmetric addition of malonic acid half-thioesters 67 to coumarins 66 using the sulphonamide organocatalyst 69. Enantioselective 1,4-addition of azadienes 71 to 3-homoacyl coumarins 70. Michael addition/intramolecular cyclization of 3

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• Sciences, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic 10.3762/bjoc.17.84 Abstract The transition metal (palladium)-catalysed asymmetric 1,4-addition of arylboronic acids to conjugated enones belong to the most important and emerging strategies

• given combination of enone and arylboronic acid. Keywords: asymmetric reaction; boronic acid; conjugated enones; chromones; enantioselective catalysis; Michael addition; Pd complexes; Introduction The asymmetric 1,4-addition of arylboronic acids to conjugated cyclic enones and chromones is a very

• the addition of the boronic acid to the β-(2-hydroxyaryl)enone could be oxidized to afford optically pure 4-phenylchroman-2-one (Scheme 1). Also in 2007, Miyaura and co-workers presented the synthesis of enantioenriched 1-aryl-1H-indenes by a tandem 1,4-addition of arylboronic acids to enones and

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• the further application of compound 2o in a cyclization reaction. Upon the treatment of 2o with zinc and chlorotrimethylsilane (TMSCl), the intramolecular 1,4-addition reaction of 2o proceeded to give the 2,2-gem-difluorochromane 3 in low yield (Scheme 3). Next, we moved on consideration of the

• previous work reported by Yagupol’skii et al. Intramolecular 1,4-addition of 2o. Proposed reaction mechanism. Optimization of the reaction conditions with phenol (1a). The reaction scope with various phenols. Supporting Information Supporting Information File 184: Characterization data for 2b–p and copies

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• to give the desired bicyclic [3.3.0] aldehyde 124 in 88% yield. A seven-step synthesis from aldehyde 124 gave azide 125. It was converted to alcohol 126 in seven steps. Alcohol 126 was treated with LDA and vinylMgBr to facilitate a γ-OH directed 1,4-addition [63] to give C-7-vinylated tricycle 127 in

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• gadolinium catalyst and chiral ligand L2 (Scheme 43b) [108]. By altering the radical precursor to α-silyl amines 277 and using α,β-unsaturated amides 278, Yoon et al. found that the reactions could be stopped at the RCA step to give enantioenriched 1,4-addition products 279 using a scandium catalyst and

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• yield and high enantioselectivity (Scheme 7) [15][16]. The Achmatowicz oxidation and ionic reduction generated the enone 58, which is regioisomeric with 53. The 1,4-addition of lithium dimethylcopper gave the desired cis-55 with high a diastereoselectivity (25:1). The cross-metathesis of 55 with 3

• fashion similar to that of the dihydropyranone 58 [16], the 1,4-addition of dimethyl copper lithium to 65 gave the desired cis-50 as a single diastereomer [31], allowing for a convergence with the route in Scheme 7. Alternatively, the Wittig methenylation of 63, followed by a silyl ether cleavage gave 66

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• . The reaction mechanism shown in Scheme 3 involves the formation of an imine upon the reaction of the primary amine with the most reactive carbonyl moiety (nonconjugated and exocyclic carbonyl function). Then, depending on the reaction conditions, the imine can react following a 1,2- or 1,4-addition

• in 10% yield. The experiments in Table 1, entries 6–11 were next performed with the aim to favor the 1,4-addition process, and thus to form the indolone 7b. Removing the acid catalyst from the reaction mixture (Table 1, entry 6) did not affect the 6b:7b ratio obtained in Table 1, entry 5. While in

• leading to the formation of the indolone 7 starts with an imine formation between the secondary amine and the nonconjugated carbonyl from the 1,4-diketone. After an imine–enamine equilibrium, an intramolecular 1,4-addition to the Michael acceptor part of the molecule occurs, followed by a prototropy

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• ketones, a 1,4-addition product was formed through a transient copper enolate, 157. With α,β-unsaturated esters, however, a carbon enolate, 160, is the intermediate. In order to maintain a catalytic cycle, iPrOH could be added to regenerate the active Cu species (Scheme 28). This study again proofed that

• dienedioates. Interestingly, tricyclohexylphosphonium tetrafluoroborate (L18), along with CuCN, resulted in the 1,4-addition as the major pathway (Scheme 32, left). By contrast, the use of the bulkier tris(2,6-dimethoxyphenyl)phosphane (L19) led to the formation of 1,6-adducts (Scheme 32, right). The Oestreich

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• of TEMPO, and thus a radical pathway was considered as less likely. Contrarily to the precedent mechanism, the authors proposed a 1,4-addition of −SeCF3, and a bromide elimination to occur. The synthesis of trifluoromethylseleno esters was also explored by the group of Weng from readily available