Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• carbonylative double cyclization process was developed obtaining 3,4-dihydro-1H-furo[3,4-b]indol-1-ones from suitably functionalized 2-alkynylanilines [20]. The reaction occurs in the presence of PdI2 (1 mol %) as catalyst and KI (10 mol %) as co-catalyst in MeCN at 120 °C for 24 h. At the end of the process

• determined by 1H NMR spectroscopy (Scheme 15). More recently, in 2016, still in Söderberg’s group, the synthesis of 2,2′-bi-1H-indoles, 2,3′-bi-1H-indoles, 3,3′-bi-1H-indoles, indolo[3,2-b]indoles, and indolo[2,3-b]indoles via reductive cyclization Pd-catalyzed was developed [36]. The reaction was possible

• leading to product formation with good to excellent isolated yields (Scheme 16). On the other hand, the synthesis of indolo[3,2-b]indoles and indolo[2,3-b]indoles were not selective leading to byproducts such as 5,7-dihydro-6H-indolo[2,3-c]quinolin-6-one, 5,11-dihydro-6H-indolo[3,2-c]quinolin-6-one, and

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• terpenes are shown. MEP: methylerythritol 4-phosphate; MVA: mevalonate; PT: prenyltransferase; TS: terpene synthase; MT: methyltransferase. Representative terpenoids produced by plant MSTSs. a) 6 and 7 are products of PamTps1 from Plectranthus amboinicus, 8–10 are products of CoTPS5 from Cananga odorata; b

• a new product of an EvVS variant with a swapped PT domain. b) From bacteria: compound 35 is a representative product of bacteria MSTSs VenA; compouns 36, 37, and 40 are products of two long β-prene TSs BclTS and BalTS. Terpenoid products of TSs using chemically synthesized noncanonical prenyl

• substrates. a) Products of BcBOT2 using iso-FPPs 45–47. b) Biotransformation of 51 by BcBOT2. c) Products of two TSs PenA and Omp6/7 using FPP ether derivative 52. PenA generated compounds 53–57 and 59, whereas Omp6/7 produced 54–59. Biotransformation of noncanonical prenyl analogs 60–65 using two terpene

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• conditions: b) 4de (0.105 mmol, 1.0 equiv), PhSH (0.16 mmol, 1.5 equiv), K2CO3 (0.21 mmol, 2 equiv), MeCN (1 mL), DMSO (0.4 mL), 25 °C, 2 h. Enantiomeric ratio (er) determined by high-performance liquid chromatography (HPLC) analysis of the purified compounds. A rationale for the catalytic cycle for the Heck

Monitoring carbohydrate 3D structure quality with the Privateer database

• Jordan S. Dialpuri,
• Haroldas Bagdonas,
• Lucy C. Schofield,
• Phuong Thao Pham,
• Lou Holland and
• Jon Agirre

Beilstein J. Org. Chem. 2024, 20, 931–939, doi:10.3762/bjoc.20.83

• model of the sugar. Also in the first section of the visual validation report is a plot of the B-factor (temperature factor) versus the real space correlation coefficient (RSCC) (Figure 2). A well-refined, well-built model would be expected to have a B-factor that increases somewhat linearly as the RSCC

• coefficient plotted against the B-factor, which enables the refinement of the sugars to be assessed. A slight negative correlation would be expected for a well-refined model. Results taken from the Privateer database report for 3QVP [28]. Table of two-dimensional Symbol Nomenclature for Glycan (SNFG

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

• Lilian M. Maas,
• Alex Haswell,
• Rory Hughes and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2024, 20, 921–930, doi:10.3762/bjoc.20.82

• , reacting BT-SCF3 with carboxylic acids 1 under similar conditions provides (trifluoromethyl)thioesters 3 via a concerted deoxytrifluoromethylthiolation process from tetrahedral intermediate A affording thiocarbamate by-product B [31]. To test whether thioester species could act as intermediates in the

• . Mechanistic experiments. (a) Conversion of thioester 3a into acyl fluoride 2a in the presence of DIPEA. (b) Conversion of thioester 3a into acyl fluoride 2a in the presence of carboxylate and fluoride nucleophiles. (c) Two-stage deoxyfluorination reaction using 0.5 equiv of BT-SCF3. 19F NMR yields using α,α,α

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• -tetrazoles (1,5-DS-1H-Ts) B. The performance of post-condensation reactions of UA-4CR adducts has resulted in various 1,5-DS-1H-Ts containing heterocyclic compounds [28][29][30][31][32], such as bis-heterocyclic lactam-tetrazoles [33][34], 2-tetrazolylmethyl-2,3,4,9-tetrahydro-1H-β-carbolines [35

• -pyrazino[2,1-a]isoquinolin-6(5H)-ones 6c–k in 73–79% yields. The presence of electron-donating or electron-withdrawing groups on the aromatic ring did not show significant effects on the Heck reaction. Products 6c–k were obtained in higher yields than products 6a,b. We believe that the secondary amine in

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• by column chromatography (heptane/ethyl acetate). Representative procedure B for the synthesis of 4a–j. A mixture of 2 (402 µmol; 102 mg), Pd(CH3CN)2Cl2 (5 mol %; 23 µmol; 6 mg), CuI (5 mol %; 21 µmol; 4 mg) was dissolved in 1,4-dioxane (5 mL) and stirred for 5 min under an argon atmosphere. NEt3 (11

• layers were dried over Na2SO4, concentrated under reduced pressure, and purified by column chromatography (heptane/ethyl acetate). Uracil derivatives in drugs. Present work as compared to previous studies [25][57][58][59]. ORTEP diagram of 5a front view (a) and side view (b). a) Interactions of the

• molecules within and between a layer with two molecules at the top and the bottom of the unit cell. b) Determined from X-ray structural analysis at 123 K. Element color: carbon (grey), hydrogen (white), oxygen (red) and nitrogen (blue). The thermal ellipsoids are drawn at the 50% probability level. UV–vis

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• , DMF/H2O, 60 °C, 18 h. (b) Pd(OAc)2, PPh3, CuI, phenylacetylene, Et3N, 50 °C, 5 h. (c) CuI, neocuproine, 4-MeOC6H4SH, NaOt-Bu, toluene, 110 °C, 13 h. (d) CuI, ʟ-proline, DMF, 80 °C, 14 h. (e) CuI, imidazole, Cs2CO3, DMF, 120 °C, 15 h. (f) 3-Methoxy-2-(trimethylsilyl)phenyl triflate, CsF, MeCN, rt, 18 h

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• , respectively. The formation of all three products 9–11 can be explained as follows (Scheme 2A) [28][29][30][31]: Due to the favorable formation of cis-5,5-fused B/C ring system, the borane reagent is preferred to approach the double bond of 1 from the α-face, to give either a secondary 1-organoborane

• spiroviolene and related natural products. Heterologous production of spiroviolene using the isopentenol utilization pathway. A) Gas chromatogram of the EtOAc extract of the fermentation broth. B) EI mass spectrum of spiroviolene. Possible cyclization mechanisms for spiroviolene (1) and related natural

• products. A) Revised cyclization mechanism for 1 that is related to deoxycondiogenol (4). B) Originally proposed cyclization mechanism for the misassigned structure 1'. C) Possible cyclization mechanism for GJ1012A (3). D) Structures of biogenetically related diterpenes during the proposed cyclization

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• diaryliodonium salt 2a. Naphthol 1a forms intermediate B with A after participation with the Cu(II) catalyst. Intermediate B generates C by radical substitution. A final intramolecular transesterification yields the benzocoumarin product 3aa. Conclusion In summary, we have employed ortho-ester-substituted

• -oxyl; BHT = butylated hydroxytoluene. Optimization of reaction conditions.a Scope of naphthols and phenols for the synthesis of 3,4-benzocoumarins.a,b. Scope of ortho-ester-substituted diaryliodonium salts.a Supporting Information Supporting Information File 16: Experimental procedures, LC–MS spectra

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• (Pj), Pseudonocardia spinosispora DSM 44797 (Ps), Mycobacterium sp. 1465703.0 (Ms), Microbispora rosea subsp. nonnitritogenes strain NRRL B-2631 (Mr)], which were synthesized and cloned into E. coli recombinant expression vectors. These homologs ranged in amino acid sequence identity from 46 to 76

• of NNG. Cells were incubated overnight in 1/5 LB, 20 µM IPTG, 3 mM NNG with appropriate antibiotics, incubated overnight at 37 °C. Molecular mass determination of purified NnlA homologs by A) SDS-PAGE or B) analytical size exclusion chromatography. Homolog labeled in figure. Mobile phase and sample

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• endocyclic olefin led to a series of separable allylic chlorides 16 and 17a,b, from direct displacement or transposition of the allylic system (Scheme 3). This substrate has previously been examined in the reaction with SOCl2 by Matsumoto et al. in THF and CH2Cl2 and similar results were obtained [28]. When

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus

• Dongxu Zhang,
• Wenyu Du,
• Xingming Pan,
• Xiaoxu Lin,
• Fang-Ru Li,
• Qingling Wang,
• Qian Yang,
• Hui-Min Xu and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73

• University, Nanjing 211198, China 10.3762/bjoc.20.73 Abstract Drimane-type sesquiterpenoids (DMTs) are characterized by a distinctive 6/6 bicyclic skeleton comprising the A and B rings. While DMTs are commonly found in fungi and plants, their presence in bacteria has not been reported. Moreover, the

• biosynthetic pathways for DMTs have been primarily elucidated in fungi, with identified P450s only acting on the B ring. In this study, we isolated and characterized three bacterial DMTs, namely 3β-hydroxydrimenol (2), 2α-hydroxydrimenol (3), and 3-ketodrimenol (4), from Streptomyces clavuligerus. Through

• these, drimane-type sesquiterpenoids (DMTs) are distinct due to their chemical structures, which feature a decahydronaphthalene core adorned with methyl groups, mirroring the A/B rings found in labdane-derived diterpenoids [5][6] (Figure 1a). DMTs exhibit significant biological activities, such as those

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

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

• addition. Therefore, anti-Markovnikov products are generally not observed. b) In contrast to the reactions with HBr (peroxide effect) [31][32], the formation of anti-Markovnikov products is low even in the presence of peroxides or photochemical activation. For instance, Whitmore and co-workers observed

• ex-situ as demonstrated very recently by De Borggraeve and co-workers (Figure 5A) [67]. In a first chamber (A) HCl (gas) was prepared from NaCl and H2SO4 which then was directed towards a second chamber (B) which contains the alkene under solvent-free conditions. The scope of this reaction (Figure 5B

•  15A). Activated and non-activated alkenes readily undergo hydrochlorination to form the corresponding tertiary and secondary chlorides (Scheme 15C). However, terminal alkenes required more forcing conditions (3 equiv of 92 and 20% of B(C6F5)3). The oligomerization of 3-chlorostyrene (product 102

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• part (α, β, γ, δ, and ε). The observed splitting of the protons a and b was presumably due to a diastereotopic effect of the methine proton c, similar to the spectrum of the monoadduct. Figure 6a shows the 13C NMR spectra of 5a in D2O and of the monoadduct in CDCl3. Together with the 1H NMR, COSY, HSQC

• by HRESIMS. HRESIMS (m/z): [M + 4H]4+ calcd for C135H149N43O16, 657.0536; found, 657.0540. a) Synthesis of C60–oligopeptide conjugates 5a–c and b) synthesis of compound 3. Fulleropyrrolidine-based biscarboxylic acid derivative 3 was prepared by Prato reaction and subsequent deprotection. Compound 3

• –peptide conjugate 5a in D2O (above) and of the precursor monoadduct in CDCl3 (bottom) at 600 MHz. 13C NMR spectrum of C60–peptide conjugate 5a in D2O and of the precursor monoadduct in CDCl3 at 150 MHz (a) and expansion of the sp2 carbon region (b). The asterisks in (a) correspond to a TFA impurity

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• synthesis and characterization of tris(carboranyl)porphyrins of A3B-type (where “B” corresponds to the substituent responsible for bioconjugate coupling) based on the transformations of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin which was used as a basic compound for the synthesis of new boronated

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• -acyltransferase polyketide synthase biosynthetic gene cluster sdl (80 kb) from Streptomyces sp. B59 was cloned and transferred into a heterologous host, Streptomyces albus J1074, resulting in the production of a class of polycyclic macrolide shuangdaolides A (1), B, and D and dumulmycin (2) [29]. Furthermore

• ansaseomycins A (3) and B. A number of factors associated with the biosynthetic gene clusters of secondary metabolites regulate their expression; thus, controlling these factors can also be used to activate secondary metabolism (Figure 2b). For example, the production of some secondary metabolites in

• et al. applied a fluorescence-based DNA cleavage assay coupled with HiTES to Streptomyces clavuligerus and identified the steroid 11α-hydroxyprogesterone (14) as an effective elicitor and characterized 10 cryptic enediyne-derived natural products, designated clavulynes A (15) and B–J with unusual

Research progress on the pharmacological activity, biosynthetic pathways, and biosynthesis of crocins

• Zhongwei Hua,
• Nan Liu and
• Xiaohui Yan

Beilstein J. Org. Chem. 2024, 20, 741–752, doi:10.3762/bjoc.20.68

• and enhance the antiepileptic effect of diazepam. The mechanism of action involved γ-aminobutyric acid (GABA) [38][39][40]. The brain-derived neurotrophic factor (BDNF)–tropomyosin receptor kinase B (TrkB) pathway is closely associated with epilepsy. Crocin can increase the BDNF level in the cortex of

• . The CsCCD2(S323A) mutant could also catalyze the conversion of β-carotene (6) to 1 [91]. BdCCD4.1 and BdCCD4.3, the homologs of CsCCD2 from B. davidii, were discovered by bioinformatic analysis. In vitro and in vivo experiments demonstrated that these two enzymes could cleave zeaxanthin (7), but the

• 2020, Xu et al. conducted a multiomics analysis of 19 ALDH genes from G. jasminoides. Among them, GjALDH2C3 was highly expressed in the fruit and flower of G. jasminoides and showed a coexpression pattern with GjCCD4a [96]. Subsequently, Diretto et al. identified BdALDH from B. davidii and confirmed

Substrate specificity of a ketosynthase domain involved in bacillaene biosynthesis

• Zhiyong Yin and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2024, 20, 734–740, doi:10.3762/bjoc.20.67

• organism shares the same habitat with the predator Myxococcus xanthus that feeds on other bacteria including B. subtilis, and bacillaene is the primary factor conferring B. subtilis cells resistance to predation by M. xanthus [8]. The identification of its biosynthetic gene cluster (bae) revealed that the

• cooperate with the PKS “in trans” [11][12]. Notably, in B. subtilis the giant bacillaene biosynthesis machinery forms an organelle-like complex that can be observed through cryoelectron microscopy [13]. The structure elucidation of “bacillaene” through extensive NMR spectroscopic methods revealed the

• , showing that the amino acid sequences of these KSs correlate with the structures of the processed PKS intermediates up to the β-carbon [20]. 13C NMR spectra of (R)-11 incubated with BaeJ-KS2 and BaeJ-KS2-C222A. A) Free 11 dissolved in incubation buffer; B) (R)-11 bound to BaeJ-KS2 after incubation and

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• strategy has been widely employed in the TE domains characterization and chemoenzymatic synthesis of other bioactive macrocyclic peptides, such as surfactin [40], streptogramin B [41], cereulide [42], seongsanamide E [43], etc. In 2005, Marahiel and co-workers accomplished the chemoenzymatic synthesis of

• type B streptogramin variants [41], including pristinamycin IE (8), which belongs to the class of depsipeptide antibiotics. Similarly, the linear peptide-SNAC was prepared through the SPPS method on 2-chlorotrityl resin, and macrolactonization was catalyzed by SnbDE TE, a thioesterase from

• , resulting in daptomycin (12) formation with a ratio of cyclization to hydrolysis of 3:1 (Scheme 4a). The significance of single amino acids for daptomycin bioactivity was evaluated, for instance, the substitution of ʟ-3-MeGlu12 by ʟ-Glu12 in Dap yielded a 7-fold increase of the MIC against B. subtilis

Genome mining of labdane-related diterpenoids: Discovery of the two-enzyme pathway leading to (−)-sandaracopimaradiene in the fungus Arthrinium sacchari

• Fumito Sato,
• Terutaka Sonohara,
• Shunta Fujiki,
• Akihiro Sugawara,
• Yohei Morishita,
• Taro Ozaki and
• Teigo Asai

Beilstein J. Org. Chem. 2024, 20, 714–720, doi:10.3762/bjoc.20.65

• GGPP, followed by hydrolysis by acid phosphatase. GC–MS analysis revealed that AsCPS synthesizes the same product to ObCPS_11g (see Supporting Information File 1, Figure S4A and B). It should be noted that the stereochemistry of CPP needs further verification due to the lack of chiral resolution of our

• bifunctional TCs instead of gene duplication TCs can also be considered (Figure 5B, model b). Conclusion Through genome mining of LRDs in fungi, we identified a unique pair of TCs in which domain organizations are distinct from those of known fungal TCs involved in the related pathways. Heterologous expression

• organizations were discovered, these enzymes would be useful to discuss and further analyze the evolution of TCs in fungi. LRDs in fungi. A) Chemical structures of representative fungal LRDs. B) Reactions catalyzed by selected fungal bifunctional TCs. Sequence analysis of AsPS and AsCPS. A) Biosynthetic gene

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• acid B(OTFE)3 had a detrimental effect (Table 7, entry 7). Increasing the stoichiometry of BF3 to 2 equivalents lowered the yield significantly (Table 7, entry 8). In contrast, the loading could be reduced to 30 mol % without impacting the formation of 4a (Table 7, entries 9 and 10). Finally, a fine

New variochelins from soil-isolated Variovorax sp. H002

• Jabal Rahmat Haedar,
• Aya Yoshimura and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2024, 20, 692–700, doi:10.3762/bjoc.20.63

• aspartate residue as a query, Nett et al. performed genome mining of photoreactive siderophores and isolated two such siderophores, variochelins A and B, from the soil bacterium Variovorax boronicumulans [5]. The Variovorax spp. belonging to plant growth-promoting rhizobacteria (PGPR) enhance plant

• this study, we isolated three new congeners of variochelin-type siderophores, variochelins C–E (3–5), along with two known compounds, variochelins A (1) and B (2), from Variovorax sp. Their structures were elucidated by a combination of NMR, ESIMS/MS, and chemical derivatization. The analysis of the

• -guanidino-3-hydroxy-2-methylheptanoate, indicating that the N-terminal fatty acyl group is a tetradecanoic acid in 2 (Figure 1 and Figure S10 in Supporting Information File 1). Therefore, compound 2 is concluded to be the known lipohexapeptide variochelin B [5]. Compound 3 has the chemical formula of

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• , Table 3 summarises the results of Henry reactions obtained by catalysis with copper(II) complexes of ligands IIIa,b. The mutual comparison of these catalysts with those composed of analogous 2-(pyridin-2-yl)imidazolidin-4-ones [5] follows several significant conclusions. For instance, the catalyst of

• IIIa,b led to a lower reaction rate compared to their pyridine counterparts. However, the cis diastereomer (IIIb) showed significantly enhanced enantioselectivity compared to its equivalent pyridine-based ligand with the same configuration (see Supporting Information File 1, part S5). This change from