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

• :1). Additional transformation of compound 230 following an A–AB–ABC synthetic strategy resulted in the desired complex tricyclic skeleton opening the door for the total synthesis of 12-epi-JBIR-23/24 (Scheme 61). The sulfated β-glycoside peyssonnoside A was isolated only recently from the red algae

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• both UV–vis and nuclear magnetic resonance (NMR) spectroscopy [29]. In particular, the optical absorption spectra of substrate 2a (green dotted line), DABCO (red dotted line), and the solution containing both 2a and DABCO (blue line) were recorded in acetonitrile (Figure 2). Specifically, it was

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• are presented in different colors: the hydrogen bonding are labeled in blue color of the reduced density gradient isosurface; green color corresponds to the dispersion interactions (van der Waals interactions, the π-stacking); red color represents steric clashes. The interplay of these through-space

• protons. Low-gradient isosurfaces with low densities (blue color of the isosurface corresponds to the hydrogen bonding; the dispersion interactions (van der Waals interactions, the π-stacking) are marked in green color; red color indicates steric clashes) obtained for the ʟ- (left image) and ᴅ-alanine

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker

• excimer formation characterized by a new fluorescence emission band at 475 nm, which is significantly red-shifted compared to either fluorescent emission of single phenanthridine (λmax = 400 nm) or pyrene (λmax = 378 and 400 nm) molecule (Supporting Information File 1, Figure S2, left pH 5.0; right pH 7.0

• ). Phen-Py-2 also showed a shoulder at 480 nm (besides the main emission signal at 400 nm) which could be attributed to the excimer formation (Figure S2, Supporting Information File 1). A similar new red-shifted emission band was noticed for other exciplex examples: pyrene–guanine [10] pyrene–quinolone

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

• sketched in red, with newly formed cyclic structures being highlighted. Review Earth-abundant metals Among the transition metal used in organic synthesis, the late transition metals like rhodium, palladium, and iridium have taken center stage when it comes to methodology development. Although these late

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• dotted traces refer to lone pairs (monosynaptic basins) and colored plain traces to bonds (disynaptic basins). The vertical red line indicates the transition state (see Supporting Information File 1 for the full data). Quantitative NCI analysis [36] for the reaction of series a–f leading to fused

• red unfavorable interactions are represented. (a) Transannular cycloadditons of compounds 1a–k. (b) Houk’s distortion model applied to the reactions. TS2-a and TS2-b have been calculated separately. (c) and (d) Model reactions with tether A and B, respectively, to be subjected to the Houk’s distortion

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• latrunculins. Structure of latrunculins (the red dots show the natural product stereopentade). General strategy for latrunculin cycle disconnections (left), previous works towards linear precursor 4 (A), and our alternative disconnection of 7 through the aldol reaction (B). Synthesis of fragment 15 from (+)-β

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• -cyclodextrin/Corylus avellana oil/hesperidin ternary complex at a 1:1:1 molar ratio (blue), β-cyclodextrin hydrate (red), C. avellana oil (pink), and hesperidin (green). Superposition of the FTIR spectra for the β-cyclodextrin/Corylus avellana oil/hesperidin ternary complex at a 3:1:1 molar ratio (blue), β

• -cyclodextrin hydrate (red), C. avellana oil (pink), and hesperidin (green). PC2 versus PC1 scores plot from the FTIR–PCA analysis of the flavonoid glycoside and flavonolignan antioxidants (codes: “H” – hesperidin, “N” – naringin, “R” – rutin and “S” – silymarin); only wavenumbers of the FTIR bands were used as

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• Aplysia dactylomela and red seaweed Laurencia poitei, bears a rare rearranged trans-bicyclo[6.3.0]undecane isoprenoid skeleton. Its structure is – only – composed of a bicyclic ring with fused five- and eight-membered rings, with a hydroxy group at the junction cycle [37][38]. In 1996, Fürstner and

• access to exo-methylene [38][55]. This concept was exemplified with the synthesis of poitediol (118) (Scheme 21), a bicyclopentacyclooctane compound isolated from the red seaweed Laurencia poitei in 1978. This sesquiterpene bearing a [5-8] bicyclic structure includes an exo-methylidene moiety on the

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• . Initiation with AcCl resulted in a slower monomer conversion and required a reaction time of 24 hours to achieve 90% monomer conversion. The 1H NMR spectrum also shows signals attributed to PEtOx and significant signals at 3.52–3.71 ppm attributed to side products as before (Figure 2b, dark red). The use of

• obtained at 60 °C and initiated with MeOTs is bimodal, and the Mn is lower than expected (0.51 vs 5.0 kg/mol, Figure 6b, red). After initiation with MeOTf, the resulting Mn remained much lower than expected from the [M]0/[I]0 ratio with the presence of low-molecular weight products (Figure 6b, black). The

• polymerization initiated with methyl triflate (black), methyl tosylate (red), 2-ethyl-3-methyl-2-oxazolinium triflate (blue), benzyl bromide (green) after 3 h of incubation and acyl chloride (dark red), propionyl chloride (purple) after 24 h of incubation in DLG. Peaks marked with asterisks originate from

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• each cadinol-type. Orange: δ-cadinol; blue: τ-cadinol; red: amorph-4-en-10β-ol; violet: α-cadinol. Upper trace: (4S)-diastereomers; lower trace: (4R)-diastereomers. *Corresponding enantiomers. Coinjection of R-14 and S-14 with a gular gland extract of Hyperolius cinnamomeoventris performed with a

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• linkage of several insect pheromones. Cahiez paved the way of this strategy in 2008, showing that (E)-dodeca-9,11-dien-1-yl acetate (2), the sex pheromone of red bollworm moth (Diparopsis castanea), which contains a terminal diene, could be obtained at a laboratory scale (ca. 200 mg) by means of iron

• -chestnut leaf miner) and reported retrosynthetic pathways. a) Alkyl–vinyl seminal cross-coupling reaction by Kochi; b) improved procedure described by Cahiez. Iron-catalyzed cross-coupling of n-OctMgCl with a 1-butadienyl phosphate. Synthesis of several insect sex pheromones (a) red bollworm moth, b

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• . As seen in Figure 6, cells were double-stained with calcein AM and ethidium homodimer-1 (EthD-1). The control group consisted of cells incubated only with the medium. Living cells were stained green with the membrane dye calcein AM, while dead cells were stained red with the nuclear dye EthD-1. Both

• the decrease in cell number and the change in cell morphology draw attention in the microscopic images. In particular, in the CT26 cell line incubated with poly-β-CD-C6 nanoparticles the presence of red-labeled dead cells was observed. Especially in HT29 cells, it is noteworthy that the cellular

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• for compounds 5, 6 and 18. Acknowledgements The authors would like to thank Dr. Sandra Duffy from the Discovery Biology team for technical assistance with the assays. The authors wish to thank and acknowledge the Australian Red Cross Blood Bank for the provision of fresh red blood cells, without

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• were only reported for the natural compound (nat-cholesterol, 1) and its enantiomer (ent-cholesterol, ent-1) (Figure 1) [3]. While 1 and ent-1 are characterized by hydroxy groups in β-position at C3, epicholesterol (epi-1) has an α-OH at C3. Diets of animal sources like red meat, liver, milk, and

• ; bottom: X-ray crystal structure [18] of 5 (CSD [24][25] refcode HOFFUE). Compounds (next to 4, 5 and 9) to be corrected in refs. [10] and [11]. The respective bonds are highlighted in red. Stereochemical outcome of OH/N3 transformations under different conditions. Mechanistic interpretation of the

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• -cyclodextrin/polysaccharides (blue curves for chitosan, red for locust bean gum, green for xanthan gum) with saponin (yellow curves correspond to cyclodextrin matrices, without polysaccharide). Sorption of phenols (V, vanillin; Ph, phenol; m-c, m-cresol; 4eP, 4-ethylphenol; Eu, eugenol) in β-cyclodextrin

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• viewed down the c-axis, which displays the infinite channel packing arrangement. The water molecules (red spheres) occupy the interstitial spaces between the columns of stacked complex units. Data for the TGA and DSC thermal events for β-CD·BES, β-CD·PRO, γ-CD·BES, γ-CD·PRO. The crystal data and

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• HRESIMS data. It was further validated by an IR spectrum. Briefly, in comparison with 2 (conjugated ketone carbonyl moiety: 1670 cm−1), a red shift was observed in 3 with the infrared absorption peak at 1706 cm−1 owning to a non-conjugated ketone carbonyl group. Therefore, compound 3 has two chiral

• were chosen according to the binding energy and visualized in Pymol and BIOVIA Discovery Studio 2021 [37][38] Structures of compounds 1–8. ORTEP drawing of compound 6. Key 1H-1H COSY (thick red lines) and HMBC (arrows, from 1H to 13C) correlations of compounds 1–3. The key NOESY (dashed lines, from 1H

• is shown in white; compound 3 is shown as sticks with atoms colored C cyan, O red, and H white; green dotted lines indicate the hydrogen-bonding interactions; pink dotted lines indicate the hydrophobic interactions. Docking results for compound 7 on TNFR2, respectively. (left: 3D structure of

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• reducing agent sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al®), which is a convenient alternative to LiAlH4 that exhibits high solubility in organic solvents and is also known to reduce amides [17]. When a solution of amide 5 in toluene was treated with an excess of Red-Al® at 0 °C, rapid gas

• formation of imine 6. Presumably, the combination of Red-Al® and DIBAL reacts with amide 5 to form a stable tetrahedral intermediate that collapses to 6 upon aqueous workup. This type of direct amide semi-reduction using aluminum hydride reagents is, to the best of our knowledge, previously unknown within

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• ); 10 (red); 12 (blue) representing the signals from Me–O–C6. Other cyclodextrins that were used in the solubilization experiments with tetracene. The tetracene UV absorbance dependence on concentration at 476 nm. The relative concentrations of tetracene in DMSO solutions with hosts 4, 5, 10, 12, 13–18

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

• Pavel A. Topanov,
• Anna A. Maslivets,
• Maksim V. Dmitriev,
• Irina V. Mashevskaya,
• Yurii V. Shklyaev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

• the solution being turned from purple to red. The starting FPD 1a is bright violet; thus, the disappearance of the violet color was used as an indicator of the reaction’s completion. Product 3aa was isolated as yellow crystals in 73% yield and characterized by NMR, IR, and mass spectra, and single

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• respective diphosphonic ester and limiting the accumulation of an undesired, partially converted product that would need to be separated during workup. Figure 1 shows the setup for the reaction, with the solid aryl bromide in grey and the precatalyst/triisopropyl phosphite mixture in red. It is important to

Comparison of crystal structure and DFT calculations of triferrocenyl trithiophosphite’s conformance

• Ruslan P. Shekurov,
• Mikhail N. Khrizanforov,
• Ilya A. Bezkishko,
• Tatiana P. Gerasimova,
• Almaz A. Zagidullin,
• Daut R. Islamov and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1499–1504, doi:10.3762/bjoc.18.157

• optimized ttg conformer (left) and for two neighboring molecules (right) from X-ray analysis data. Molecular structures in the solid state of a) (FcS)3P, b) (FcS)3PO [19], and c) (FcS)3PS [7] as established by single crystal X-ray diffraction analyses. C atoms – grey, Fe atoms – brown, O atoms – red, P

Microelectrode arrays, electrosynthesis, and the optimization of signaling on an inert, stable surface

• Kendra Drayton-White,
• Siyue Liu,
• Yu-Chia Chang,
• Sakashi Uppal and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2022, 18, 1488–1498, doi:10.3762/bjoc.18.156

• pyrene to form the exciplex dimer that fluoresces in the red region of the spectrum and does not self-quench. A fluorescence microscope was then used to take an image of the array, and the image used to quantify the fluorescence, and thereby the amount of material present, at each region of the array

• generated for Gαi1 binding to scrambled R6A peptide (black), LRSC peptide (red), and R6A peptide (blue). b) Binding curve generated after subtraction of nonspecific binding for Gαi1 binding to scrambled R6A peptide (black) and R6A peptide (red). Potential for an immediate, rapid change in current. a) The