Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• – anionic, Lys – cationic, Leu – hydrophobic) affects their binding by the receptor. Additionally, to probe whether the chiral glucose backbone of the receptor allows to achieve selective binding of one enantiomer of tryptophan over the other we used both ʟ- and ᴅ-tryptophan as guests. The binding of amino

• towards ʟ-Trp over its ᴅ-enantiomer (entries 1 and 6, Table 1). Since tryptophan fulfills many of its biological functions as a component of peptides and proteins [2][3][4][5], we also probed, if 1 can recognize tryptophan residues within peptide sequences. For this purpose, we prepared six model

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• chromatography [1]. Sometime later, kinetic resolution (KR) emerged. This method is based on the different reaction rates of each enantiomer in a racemic mixture when they are reacted with a reagent, a chiral catalyst, or an enzyme. This process results in obtaining the less reactive enantioenriched enantiomer

• catalyst or the bistrifluoromethyl-substituted analog B could enable the retro-Michael reaction of only one enantiomer of the racemic mixture, potentially leading to a kinetic resolution of the 1,5-dicarbonyl compounds (Scheme 2). Results and Discussion An initial attempt was made to determine if the retro

• , enantioselectivity increased until a specific time, and after that, the enantiomeric ratio decreased (compare entries 1–3 and 21–23 in Table 1). The interesting result is that the major enantiomer in the enantioenriched mixture is now the opposite of the one obtained when the ketone and the α,β-unsaturated aldehyde

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

• acidic hydrogen of the CPA promotes dehydration and the formation of the vinyliminium intermediate. Chirality control is consistent because of the retarded reaction with the unfavored enantiomer of the bisindole 142 and its low rotational barrier resulting in quick exchange between the two. Products 147

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

•  19) [70]. According to the screening studies, a mixture of enantiomers was obtained, with one enantiomer predominating (95 to >98% ee) under the optimized conditions. The phenyl with electron-deficient groups is well tolerated and produces outstanding yields. Moreover, the phenyl with a bulky

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• )-enantiomer of 5e and therefore, these compounds were classified as inactive. The docking results are shown in Table 3. Compounds 4a–e bind to the active site of CYP51 with affinities ranging from −7.7 to −8.8 kcal/mol and compound 5e has a much higher affinity of −5.4 kcal/mol. Therefore, we assume that the

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• strategically modifying LB substituents to induce asymmetry, a stereoselective catalytic scaffold was developed, favouring one enantiomer from both epoxide enantiomers. This work advances the in silico design of FLPs, highlighting their potential as asymmetric CCU catalysts with implications for optimising

• –CH(CH3) bond. Additionally, the (S)-epoxide enantiomer was employed consistently. Symmetric FLP scaffolds – achiral environment Following the initial exploration and preliminary results, our attention shifted toward the identification of a suitable catalyst. Drawing inspiration from the literature

• was engineered to produce a single enantiomer preferentially from both enantiomers of the epoxide substrate. An enantiomeric excess of 95%ee was initially achieved, with the predominant (R) enantiomer. Enhanced selectivity was subsequently observed through additional transition states, resulting in a

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• supramolecular helices [45]. SEM was used to investigate the structures resulting from the self-assembly of a bis-bipyridinium-based compound (1·4Br) resulting in helical supramolecular fibres with different chirality induced depending on the enantiomer of tryptophan present. The direct images obtained from SEM

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

• -imine is activated either with a Brønsted or Lewis acid. In both cases, the allyl group of the silane reagent 46 attacks from the Re-face of the imine, leading to the major (R)-enantiomer of 47. Based on the experimental data obtained with the preformed silylated catalyst and preformed imine, the Lewis

• absolute configurations of homoallylamines 66 were assigned by analogy to 67, the configuration of which was determined after removal of the N-aryl group and comparing the optical rotation with the literature values for the known enantiomer (S)-69 (Scheme 14). The proposed stereochemical model suggests

• employing chiral Brønsted acid catalyst (S)-TRIP (118) (Scheme 25). In this approach, the racemic β-formyl amide forms the iminium intermediate that undergoes fast equilibration via the enamine tautomer to form preferentially one enantiomer which then undergoes the acid-catalysed aza-Cope rearrangement

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• develop a comprehensive model, finding that imine parameters govern the defining transition state and hence the preferred enantiomer. In a focused modelling, two separate models are constructed, one for all E- and Z-imines, respectively, finding substrate–catalyst matching is important for E- and Z-imines

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• (Figure 14) [249]. While most of the investigations including the X-ray data suggested that this natural product occurs as a racemate [38][74][147][162][248][249], it was occasionally obtained as the (−)-enantiomer [250][251]. The assumption that the methyl group in (−)-altenuene has the same orientation

• ]. Isoaltenuene (55), the 4a-epimer of altenuene, was first isolated from Alternaria alternata [260]. Its proposed structure including its relative configuration was determined by NMR spectroscopy and unambiguously confirmed by total synthesis of the (+)-enantiomer [249]. Whenever the chirality was determined, it

• was either isolated as (−)-enantiomer (from A. alternata) [250], as the (+)-enantiomer (from unidentified freshwater [251] or marine [261] fungi), or as the racemate (from Nigrospora sphaerica, A. alternata, and Phialophora sp.) [162]. It was further isolated without specification of the chirality

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• a pair of enantiomers with a ratio of 9% R and 91% S using the Ohrui–Akasaka method [127]. Structurally, compound 21 represents the second example with a (R)-anteiso enantiomer in addition to nocapyrone L [128]. An antimicrobial activity assay showed that compounds 21–23 could inhibit the growth of

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

• the conjugate addition product 3aa in 58–62% yield with 74% ee (Table 1, entry 1). On the other hand, 9-amino-9-deoxyepicinchonine (II) [30] furnished the opposite enantiomer ent-3aa in 62% yield and 66% ee (Table 1, entry 2). Among the screened organocatalysts (see Table S1 in Supporting Information

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

• followed by a sequential Jones oxidation. The overall method displays a broad scope and good enantioselectivity, favoring the (R) enantiomer. The applicability of the protocol is highlighted by the efficient enantioselective syntheses of the selective phosphodiesterase-4-inhibitor rolipram and the

(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

• are significantly increased compared with the parent compound. The observed aqueous solubilities of BCPs (+)-21 and (−)-21 were much higher than that of telmisartan. For the lomitapide isosteres (+)-22 and (−)-22, the solubility was different for each enantiomer; while 1,2-BCP (+)-22 showed increased

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

• depends on the relative configuration of the ligand used; cis-configuration of ligand affords the nitroaldols with major enantiomer S- (up to 97% ee), whereas the application of ligands with trans-configuration led to nitroaldols with major R-enantiomer (up to 96% ee). The “proline-type” ligand IV was

• -enantiomer. A possible explanation of these results is illustrated in Figure 2, which shows plausible transition structures for the Henry reaction. Due to the Jahn–Teller effect, i.e., distortion of the octahedral Cu(II) complex forming four equatorial and two perpendicular coordination sites [18], the

• nitroaldols were obtained with an excess of S-enantiomer, likewise in catalysis by copper(II) complexes of ligands Ic, IIc and IIIb, as well as ligands based on pyridine-(imidazolidin-4-one) [5][6][7] owned the S-configuration at the imidazolidin-4-one ring (see Supporting Information File 1, part S5). Hence

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

• products) [26]. HPLC: Phenomenex Lux Cellulose-3 column (3 mm, 250 × 4.6 mm), eluent CH3CN/H2O (0.1% formic acid) 40:60, isocratic mode; 0.6 mL min−1; UV detector 222 nm, 30 °C. The retention time for the (S)-enantiomer was 12.3 min, for the (R)-enantiomer 14.7 min. General procedure for recycling of the

• min−1; UV detector 265 nm, 35 °C. The retention time for the (S)-enantiomer was 27.2 min, for the (R)-enantiomer 29.1 min. General procedure for recycling of the lipophilic organocatalyst in the stereoselective Michael addition of the cyclohexyl derivative of Meldrum’s acid to 4-chloro-trans-β

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

• concomitant deprotection of the nitrogen and the ester groups. The sample was found to have a negative optical rotation, thereby indicating that the major enantiomer present had S configuration [26]. This allowed to establish that the configuration of the major diastereomer present in (RS)-14b was (RS,S), and

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• = +95.9 (c 0.55, CH2Cl2) pointed to the same enantiomer as is known from the plants Pinus sibirica ([α]D20 = +118.4) and Torreya nucifera ([α]D18 = +118.6) [34], and from the fungus Xylobolus frustulatus ([α]D25 = +99.9 (c 0.6, CHCl3)) [35]. This finding is rather unusual, as more and more cases were

• by NMR spectroscopy confirmed the identity of the enzyme product α-cadinene (Table S3, Figures S13–S20, Supporting Information File 1). The optical rotation of [α]D25 = +60.0 (c 0.015, C6D6) indicated the opposite enantiomer as in the plant Humulus lupulus ([α]D24 = −62.4 (c 0.868, CHCl3)) [37

• ). The optical rotation of [α]D25 = –9.4 (c 0.64, CH2Cl2) pointed to the same enantiomer as in the plant Viguiera oblongifolia ([α]D24 = –8 (c 0.4, CHCl3)) [43]. A (−)-amorpha-4,11-diene synthase (ADS) is also known from Artemisia annua and catalyses the first committed step in the biosynthesis of

Correction: Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 1370–1371, doi:10.3762/bjoc.19.97

• theoretical ECD spectra of both enantiomers to determine the absolute configuration. By comparison of the recalculated and the experimental spectra, it became evident that in fact, the (3S,4S)-enantiomer rather than the (3R,4R)-enantiomer was obtained (Figure 2). Consequently, in the first paragraph of the

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• alcohol functions of 4.5 were deprotected in acidic media to produce 3-O-octadecyl-sn-glycerol (4.6). The enantiomer of 4.6 was obtained from 4.4 by protecting the primary alcohol with a benzyl group to give 4.7. Then, the deprotection of the two alcohol functions with H2SO4 in water followed by the

• , both enantiomers were reported. For the control of the chirality in position 2 of glycerol, (S)-solketal (17.1) was used as starting material to prepare first the hexadecylglycerol (R)-17.2 which was converted to its enantiomer following a five-step sequence (Figure 17A). First, tritylation and

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

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• this helical aza-NG was achieved by introducing a chiral auxiliary reagent at the nitrogen site [40], and the racemization barrier of one enantiomer was measured as 26.2 kcal/mol by monitoring the changes of CD spectra at 60–80 °C. The synthesis started with the Diels−Alder reaction of 5H-dibenzo[b,f

• racemization was observed by heating the enantiomer for 1 hour at 120 °C. Except for [5]helicene, Narita and co-workers also reported [7]- or [9]helicene-containing chiral NGs [42]. As shown in Scheme 4, dibromo-functionalized 1,2,3,4-tetraphenylbenzene 32 was treated with DDQ and TfOH to produce dibromo 33 as

• Gibbs activation energy of enantiomer 53 for the racemization process was determined as 33.0 kcal mol−1 at 298 K. The CPL spectra of M-53 and P-53 showed an emission maximum at 560 nm with glum value of 2.3 × 10−4. Instead of helicene formation in the final Scholl-type ring formation step, Martín and co

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• corresponding R,R-iPrBox-ligand the second enantiomer, (R)-arylglycine 10l could be prepared with a similar yield and enantioselectivity. Conclusion In summary, we have reported a palladium-catalyzed enantioselective three-component reaction of aryltrifluoroborates, sulfonamides, and glyoxylic acid. This method

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• , MeOH); lit. −44 (c 0.05, MeOH)) [18], confirming the same absolute configuration these compounds should be derived from the same biosynthetic pathway. In addition, the ECD spectra of (5S,8R,9S,10R,14S)-1 and its enantiomer were calculated at the B3LYP functional using a TD–DFT method [19]. As

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• configuration of each enantiomer was determined by single-crystal X-ray analysis. In addition, a one-pot synthesis of (±)-incarviditone has been achieved from rac-rengyolone by using KHMDS as a base. We have also assessed the anticancer activity of all the synthesized compounds in breast cancer cells

• 'S, 9'R (Scheme 6). After separation of individual enantiomers, we recorded the CD spectra of both enantiomers in MeOH. (−)-Incarvilleatone [(−)-1] shows a negative optical rotation and a negative Cotton effect in the CD spectrum whereas the other enantiomer (+)-incarvilleatone [(+)-1] showed a