Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• the diastereoselectivity of the nucleophilic attack of the β-lactam on the radical cationic intermediate was influenced by stereoelectronic factors. Compounds unsubstituted at position C-3 of the β-lactam ring, 11d–h, showed modest stereoselectivity with a higher dr (6.7:1) for compound 11d, which has

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• high stereoselectivity were similarly recorded for the other substrates 2c and 2d possessing different Rf groups at the 3 position (Table 2, entries 1–3). Mixing of 2b with different primary (entries 4–7 in Table 2) and secondary (entries 8 and 9) amines led to the formation of the respective products

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• selected recrystallised products showed 98–99% ee. Importantly, both silane and stannane-based protocols were successfully performed on a 5 mmol scale using substrates 52 and 59. There was a slight loss in yield and a negligible decrease in stereoselectivity in the case of 2,3-dimethylallylation product 52

• . The limitations in the scope of this methodology include a poor stereoselectivity achieved with 5-membered cyclic 2,3-disubstituted silanes in contrast to the 6-membered analogues (53). A lower efficiency was recorded with 2-substituted allylsilanes bearing either a halogen or an alkyl group with

• the aromatic group of the substrate had a significant contribution to the stereoselectivity of the reaction. The reaction demonstrated a broad scope both in the acetal 98 and in the allylsilane (Scheme 20). A high enantioselectivity was achieved even with the non-aromatic 1-cyclohexene-1

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• Technology, wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland 10.3762/bjoc.20.198 Abstract The study presents a novel approach utilizing iminium salt activation and mild enolization of thioesters, offering an efficient and rapid synthesis of Michael adducts with promising stereoselectivity and marking a

• products with 61% and 63% yield in the solution and mixer mill, respectively. However, the drop of stereoselectivity was noted in comparison to the reaction in toluene (94% ee vs 86% ee in mixer mill, ∆ee = 8). It should be noted that the dibenzyl malonate remained inactive for subjecting to reaction under

• Information File 1). However, the low stereoselectivity is not surprising. The analysis of the covalent adduct of cyclopentenone with amines may result from the “flattened” of the small system that renders them less sensitive to steric interactions generated by the catalyst compared to cyclohexenone [42][43

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

• the support [8][67]. Adsorption is a non-covalent reversible technique for attaching organocatalysts to supports. It offers a facile and modular construction of immobilised chiral catalysts with maintained or even improved activity and stereoselectivity [68][69][70]. The main advantages of catalyst

• -nitrostyrene, the recyclability of the organocatalyst in the betaine/sorbitol/water DES system was demonstrated up to 10 cycles without any significant decrease in yield (up to 99%) or stereoselectivity (up to 96% ee). Encapsulation is an irreversible method and the only catalyst immobilisation process that

• support can lead to lower stereoselectivity, as previously shown in Scheme 4. Solutions for limitations of solid-supported organocatalysts The properties and applicability of an immobilised catalyst depend not only on the immobilisation method and the physicochemical characteristics, porosity, and

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

• Deepa Nair,
• Abhishek Tiwari,
• Banamali Laha and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177

• reported in due course. Biologically active derivatives of cyclohexanones. X-ray structure of 4a (CCDC 2351387). Origin of stereoselectivity in the double Michael addition. The Michael donor–acceptor reactivity of curcumin: previous vs present work. A plausible reaction mechanism. Scale-up reaction

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• ; this reaction is catalysed by S-adenosylmethionine (SAM or AdoMet)-dependent methyltransferases (MTs). These enzymes are known for their excellent chemo-, regio-, and stereoselectivity [3][4][5][6]. Their ability to introduce methyl groups at specific positions within ribosomal peptides equips the

• . Additionally, stereoselectivity can be achieved by using potassium bis(trimethylsilyl)amide for deprotonation and methylation with MeI [33][39]. Any of these routes would yield methylated amino acids that can then be incorporated into an oligopeptide in solid-phase peptide synthesis (SPPS). Additionally, N

Bioinformatic prediction of the stereoselectivity of modular polyketide synthase: an update of the sequence motifs in ketoreductase domain

• Changjun Xiang,
• Shunyu Yao,
• Ruoyu Wang and
• Lihan Zhang

Beilstein J. Org. Chem. 2024, 20, 1476–1485, doi:10.3762/bjoc.20.131

• stereochemistry. However, the reliability and applicability of these prediction methods have not been thoroughly assessed. In this study, we conducted a comprehensive bioinformatic analysis of 1,762 KR sequences from cis-AT PKSs to reevaluate the residues involved in conferring stereoselectivity. Our findings

• adopted, the prediction accuracy and the applicable range of these conserved motifs remain elusive, and not a few exceptions to these prediction rules have been reported (Figure 1c). For instance, the stereoselectivity of KR7 of ibomycin [12], KR15 of neaumycin B [14], and KR7 and KR10 of rifamycin [18

• evaluate the sequence–stereoselectivity relationship of KRs, here we have collected 1,762 KR sequences from modular cis-AT PKS gene clusters, whose product structures have been verified using spectroscopic and/or chemical methods. We reveal that the previously identified conserved motifs are best

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• using tertiary alkyl oxalates and aryl bromides (Scheme 10). This is achieved through the synergistic combination of photoredox and nickel catalysis. This approach facilitates the formation of diverse trisubstituted olefins with outstanding regioselectivity and syn-stereoselectivity. The proposed

• achieving good syn-stereoselectivity. In 2019, using a similar concept, they reported 1,2-alkylarylation of alkenes with alkyl oxalates and aryl bromides under visible-light photoredox and Ni catalysis (Scheme 11) [48]. This protocol was applicable to a wide range of substrates, such as nonactivated alkenes

Sustainable tandem acylation/Diels–Alder reaction toward versatile tricyclic epoxyisoindole-7-carboxylic acids in renewable green solvents

• Ayhan Yıldırım

Beilstein J. Org. Chem. 2024, 20, 1308–1319, doi:10.3762/bjoc.20.114

• yields and the desired stereoselectivity [59][60][61]. The viscous nature of the aminofuranes usually requires the use of toxic solvents such as toluene, and in some studies, solvents such as DMSO, which are difficult to remove from the reaction medium [62][63][64]. Although solvent effects are of little

• synthesis scheme of various epoxyisoindole-7-carboxylic acids synthesized using the reaction conditions given in Table 1, entry 4 are given in Table 2 and Scheme 1, respectively. In general, IMDAF reactions proceed with high stereoselectivity to form the major exo addition product, in contrast to

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• [6][59]. Kropp and co-workers also investigated the stereoselectivity for the hydrochlorination of 1,2-dimethylcyclohexene (29) (Scheme 12) [58]. They found a significant dependence of the stereoselectivity on the reaction time. After 1 minute a 88:12 cis-30/trans-30 ratio was observed which, after 2

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

• allenes that were never used as substrates in interrupted radical Heck/allylic substitution reactions. As summarized in Scheme 3, unsaturated γ-AA derivatives were observed in this reaction albeit with poor stereoselectivity. Linear amines containing alkyl, hydroxy, and terminal alkenyl groups were

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• , only the E-isomer was observed, as confirmed by 1H-1H 2D-NOESY NMR spectrum (Figure 4). This is not surprising because similar stereoselectivity has been reported in the photoinduced [2 + 2] cycloaddition reaction of empty C60, where the E-isomer is most thermodynamically stable [19][22]. The positive

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• and straightforward as it is usually considered. Keywords: concentration; glycosylation; protecting groups; reactivity; sialic acids; stereoselectivity; Introduction Glycoconjugates containing sialic acid occur on the surface of all cell types in a variety of organisms. They participate in a broad

• the stereoselectivity of sialylation, it is important to analyze anomeric ratio values (α/β) for the disaccharide fraction separated by size-exclusion chromatography since the retention values of different disaccharide anomers on silica gel may be surprisingly large and a minor isomer may be lost

• concentration (0.05 mol·L−1) differences between the reactions involving sialyl donors 1 and 2 are small (see Figure 2 and Table S1 in Supporting Information File 1). Noteworthy is a slightly higher stereoselectivity achieved when sialyl donor 1 with a trifluoroacetyl group at O-9 was used (α:β = 16:1 for 1

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• )benzenesulfonamides to give chiral azepane spirooxindoles with excellent stereoselectivity (reaction 2 in Scheme 1) [55][56]. Du and co-workers reported a DABCO-mediated [4 + 3] cycloaddition reaction between o-quinone methides and isatin-derived MBH carbonates to give functionalized benzo[b]oxepine derivatives in

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• stereoselective Michael addition reactions. Homogeneous catalysis was carried out in non-polar solvents (i.e., toluene), which allows the high performance of the lipophilic organocatalyst in terms of yield and stereoselectivity. To facilitate the pharmaceutical use of the lipophilic organocatalyst, we

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

• ][56][57][58]. The [3 + 2] cycloadditions of AMYs B1–B4 with alkenes lead to the formation of cycloaddition products 3a–d with attenuated regio- and stereoselectivity, since the Ar group is not strong enough to fully localize the negative charge on the carbon connecting to Ar in the 1,3-dipoles. Both

• stereoselectivity which limits the synthetic utility of non-stabilized AMYs of type C. There are over 300 papers on the amino acid-based decarboxylative [3 + 2] cycloadditions of N–R-type AMYs B1 (such as that derived from proline) and B2 [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49

• stereoselectivity (Scheme 3) [61][62]. From the results shown in Scheme 2 and Scheme 3, we envisioned that pyrrolidines 3c or 3d generated from the cycloaddition of AMYs B3 or B4 could undergo a second cycloaddition to form double cycloaddition products 4a or 4b (Scheme 4). The double cycloaddition process involves

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• a thiol to a C–C double bond and was first reported in 1905 [80]. It is considered as a click chemistry reaction due to its high yield, stereoselectivity, rate, and thermodynamic driving force. Generally, the thiol–ene reaction is conducted under radical conditions, often photochemically induced [81

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

• with the starting acrylate for 1 h prior to the addition of air had a significant impact on the stereoselectivity. When air was introduced directly after Et2Zn (Table 3, entry 3) a much lower 59:41 dr was observed. This behavior was suggestive of the need for coordination of diethylzinc both to the

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• reactive and difficult to isolate. The NHC–Cu complex also helps to control the regioselectivity and stereoselectivity of the reaction, which are of high importance in organic synthesis. Overall, the use of NHC–Cu complexes as catalysts for conjugate addition reactions offers a highly efficient and

• functionalities, applicability to a wide range of heteroarenes and allyl halides, and high stereoselectivity (Scheme 71). The enantioselective C(sp2)–H allylation of (benz)oxazoles and benzothiazoles with γ,γ-disubstituted primary allyl phosphates catalyzed by NHC–Cu(I) complexes was reported by Ohmiya, Sawamura

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• and stereoselectivity (Scheme 8) [58]. The mechanism of this reaction differs from the previously reported ones and proceeds through the in situ generation of nucleophilic and electrophilic partners which provides new opportunities for enantioselective oxocarbenium ion-driven CDC processes. Due to an

Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• self-aldol condensations, polymerization and Tishchenko-type processes) and stereoselectivity [20]; the activation of acetaldehyde via aminocatalysis, furthermore, suffers from a lack of proper steric hindrance for the enantio-discrimination process. However, some methodologies enabling the use of

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• stereoselectivity is also explained. Keywords: asymmetric; aza-Friedel–Crafts reaction; H-bonding; organocatalysis; stereoselectivity; Introduction The ease of a chemical transformation depends on the thermodynamic instability of a chemical bond owing to its fast cleavage under mild reaction conditions. A C–H

• nitrogen and the catalyst which selectively blocks one face of the imine’s plane. This forces the nucleophile to approach from the opposite face thus imparting stereoselectivity into the products. The first organocatalyzed asymmetric aza-Friedel–Crafts protocol was published by Terada and co-workers in

• . Stereoselectivity in the products 10/11 was achieved by using the chiral spirocyclic phosphoric acid catalyst P3 which, through H-bonding interactions with the nucleophile and the electrophile, forces the nucleophile to approach the C=N plane from the Re face. In general, enantiocontrol with pyrroles was better