Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• bromide (see Supporting Information File 1). Subsequent Buchwald–Hartwig reaction with 1,3-dibromo-7-tert-butylpyrene (2) gave the [2 + 2] macrocyclic precursors 3a,b as the major product in 16%/10% yields, and trace amounts of higher oligomers as detected by mass spectrometry. Notably, compounds 3a,b

• % and 90%, respectively. For MC2, four C–C bonds are formed between the dichlorobenzene units and tert-butylphenyl groups, generating two dihydroindolo[2,3-b]carbazole subunits. In contrast, there is only one newly formed C–C bond between the dichlorobenzene unit and one pyrene moiety for MC1

• planar dihydroindolo[2,3-b]carbazole subunits orienting upwards with a dihedral angle of 75° and two pyrene units downwards (Figure 2b). Besides, the central cavity is highly symmetric, and the shortest diameters are determined to be 4.34 Å and 4.99 Å, respectively. In contrast to MC2, MC3 shows an

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• interactions with the enehydrazine intermediate, which is essential for achieving high levels of stereocontrol. Using the optimal catalyst CPA 1, a series of aza[6]helicenes 3a,b was synthesized with excellent enantioselectivity and high yield. However, this method demonstrated notably reduced efficiency and

• demonstrated the successful construction of planarly chiral macrocycles with 12- to 14-membered ansa chains with high enantioselectivity when using NH2 as the directing group (see 33a,b). However, extending the ansa chain to 15 members led to the loss of planar chirality due to insufficient steric hindrance to

• for the asymmetric synthesis of saddle-shaped inherently chiral dibenzo[b,f][1,5]diazocines 72 via CPA catalysis [55]. In the presence of CPA 7 (10 mol %) and the corresponding 2-acylaniline 73 (20 mol %) as co-catalysts, the asymmetric dimerization of 2-acylbenzo isocyanates 71 allowed access to

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• catalysis via the rational functionalization of MOF pores. Schematic representation of the modulation of MOF pore environments. A) de novo synthesis of several MOFs requiring the multistep synthesis of different organic linkers. B) Synthesis of several frameworks from a single parent MOF using post

• -synthesis modification (PSM). A) Schematic representation of the reaction of KSU-1 with aliphatic isocyanates and the estimated conversions at –OH and –NH2. B) The corresponding 1H NMR spectra of the MOF reaction products digested in a solution of D2SO4 in DMSO-d6. A) Schematic representation of the

• reaction between benzaldehyde and malononitrile to form benzylidenemalononitrile (BMN). B) Representative 1H NMR spectra for the reaction of benzaldehyde and malononitrile in toluene with dodecane as internal standard, analyzed after 30 minutes. Graphical representation of the Knoevenagel catalysis results

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• forward and backward isomerisation can occur simultaneously. Moreover, some unwanted photochemical side reactions ΦS can occur, as shown in the Equation 4: A is one state of the photoswitch, B the second state, and B’ a generic degradation product. Fatigue resistance measures how many times the

• be synthesised through oxidation of aminoheteroarenes 12 (Scheme 4A) or reduction of nitroheteroarenes 13 (B). Bayer–Mills coupling (Scheme 4C) is suitable for both symmetric and asymmetric targets, usually in acidic conditions. Basic conditions [14] are more effective with very electron-poor

• aromatic amines. Another strategy for both symmetric and asymmetric targets is the azo coupling of a diazonium salt 15 (Scheme 5A) with a nucleophile, which can be a (hetero)aromatic 16 [29] (B), a lithiated ring 19 [39] (C), or a precursor 20a,b [29][32][40] (D). In case of more than one reactive position

[3 + 2] Cycloaddition of thioformylium methylide with various arylidene-azolones in the synthesis of 7-thia-3-azaspiro[4.4]nonan-4-ones

• Daniil I. Rudik,
• Irina V. Tiushina,
• Anatoly I. Sokolov,
• Alexander Yu. Smirnov,
• Alexander R. Romanenko,
• Alexander A. Korlyukov,
• Andrey A. Mikhaylov and
• Mikhail S. Baranov

Beilstein J. Org. Chem. 2025, 21, 1791–1798, doi:10.3762/bjoc.21.141

• product. Next, using the revealed optimal reaction conditions, we studied its scope on a variety of arylidene-azolones 1–4 (Scheme 3). We also tried to apply both proposed approaches (methods A and B) to the series of derivatives 5. In contrast to the results obtained previously for N-benzylazomethine

• would be of help in further drug design of spirocyclic scaffolds. Single crystal X-ray analysis for the compounds 6e (A), 7d (B), 8e (C) and 9e (D). Atoms are shown as thermal ellipsoids at 50% probability. All hydrogen atoms, except the one at the stereogenic center, are omitted for clarity. Synthetic

Synthesis of chiral cyclohexane-linked bisimidazolines

• Changmeng Xi,
• Qingshan Sun and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1786–1790, doi:10.3762/bjoc.21.140

• nucleophilically attacks the phosphonium in A to generate intermediate B by loss of triphenylphosphine oxide and triflic acid. The nucleophilic sulfonamide in B intramolecularily attacks the generated imine moiety in B to form intermediate C, in which triflic acid may protonate the imine moiety in B to assist the

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• halogen bonding observed in C–N atropisomeric quinazolinone I and quinazoline-thione II. Although the catalytic asymmetric synthesis of N-(2-bromo- or 2-chloro-phenyl)quinolin-2-ones 1a,b was recently attempted by Doerfler et al., the yields were moderate (33% and 48%) and the enantioselectivities were

• poor (11% ee and 9% ee) [31]. In addition, rotational stability about the C–N bond in 1a,b was not mentioned at all. We prepared racemates rac-1a,b in accordance with Scheme 1 and separated their enantiomers [(P)-1a,b and (M)-1a,b] through medium pressure liquid chromatography (MPLC) using a semi

• -preparative chiral IH column. The rotational barriers of 1a and 1b were evaluated to be 32.0 and 30.8 kcal mol−1, respectively, by a thermal racemization experiment of the separated (P)-1a and (P)-1b. In contrast to quinolinones 1a,b, the atropisomers in the precursors (3,4-dihydroquinolinones 4a,b) could not

Thermodynamics and polarity-driven properties of fluorinated cyclopropanes

• Matheus P. Freitas

Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137

• molecules (QTAIM) analyses were carried out with the AIMAll program [27]. Structures of fluorinated cyclopropanes evaluated in this study through quantum chemical methods. (a) Electrostatic potential map of 1.2.3-c.c., highlighting the negative region (top side) and positive region (bottom side). (b) Top

Preparation of a furfural-derived enantioenriched vinyloxazoline building block and exploring its reactivity

• Madara Darzina,
• Anna Lielpetere and
• Aigars Jirgensons

Beilstein J. Org. Chem. 2025, 21, 1737–1741, doi:10.3762/bjoc.21.136

• -wise process [22]. The first step involves addition of the oxazoline nitrogen to TsNCO leading to a zwitterionic intermediate A, which undergoes 1,4-conjugate addition forming a cyclic intermediate B. Subsequently, the electron-rich double bond in intermediate B reacts with a second equivalent of TsNCO

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• neurological disorders [7] and possibly other non-skin diseases [5]. These fungi, especially M. furfur, convert tryptophan into various alkaloid indoles such as malassezione (1), malassezin (2), which cyclizes to indolo[3,2-b]carbazole (3), other related indolo[3,2-b]carbazoles (4–7), pityriarubins (8–10), and

• the presence of the indole groups. General procedure for the synthesis of ketones 25a,b, and d from acids 24a,b, and d. Adapting DCC/DMAP protocols reported previously [22][23][24][25][26][27], an oven-dried 50 mL flask equipped with a magnetic stir bar was charged with the acid (1 equiv, typically

• ] or B) indole-3-acetic acid. Various bis-substituted ketones prepared. a25c prepared from 25b. Supporting Information Supporting Information File 6: Copies of NMR and MS spectra of synthesized compounds. Funding This work was supported by a Discovery Grant from the Natural Sciences and Engineering

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• that we reacted either (S)- or (R)-H-2 with the dichloride (S)-iPr-62 to give the diastereomeric macrocycles (S,S)-HiPr-M22 and (R,S)-HiPr-M22 in 73/49% yield, respectively. The 1H NMR spectra of the C2-symmetric derivatives (S,S)-H/iPr-M22 (see Figure 8a/b) differ most significantly in the splitting

• routes towards macrocycles featuring one BINOL unit. a) Two-fold Suzuki coupling and b) two-fold Williamson synthesis. Reagents and conditions: i) bis(boronic ester) 75/6/7/8 (1.0. equiv), Pd2(dba)3 (0.1 equiv), P(o-Tol)3 (0.2 equiv), n-Bu4N+OH− (3.2. equiv), toluene/H2O 5:1, 90 °C; ii) ethylene glycol

• -62; ii) Me/(S)-H/(R)-H/iPr-2 (1.0 equiv), Cs2CO3 (3.2 equiv), CH3CN, 80 °C. 1H NMR spectra of a) (S,S)-H-M22, b) (S,S)-iPr-M22, c) (S,S)-HiPr-M22, and d) (R,S)-HiPr-M22 (all: 400 MHz, CDCl3, 298 K, for labelling see Figure 7). Supporting Information Synthetic procedures and NMR spectra for all new

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• nitric acid and the model was formulated to predict the reaction outcome at large capacity. Lan and Lu [32] developed a method for the rapid determination of lumped kinetics for the nitration of o-dichlorobenzene by processing the profile of adiabatic temperature rise in a micropacked-bed reactor. Type B

Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides

• Tsun-Yi Chiang,
• Mei-Huei Lin,
• Chun-Wei Chang,
• Jinq-Chyi Lee and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131

• a = 16.1017(4) Å, b = 7.7608(2) Å, c = 28.8344(8) Å, and β = 93.3680(10)°. Additionally, the presence of lattice water greatly influenced the molecular packing. The hydrogen bond (H–O–H) lengths in this lattice water ranged from 1.923 to 2.204 Å (Figure 2b). The pyruvylated galactose 6 was utilized

• ), 1.15 EPS (2) and Rhizobium leguminosarum bv. viciae VF39 EPS (3). (a) Oak Ridge Thermal Ellipsoid Plot view of the X-ray crystal structure of pyruvylated galactose 6. (b) Hydrogen-bonding in the crystal structure of pyruvylated galactose 6. Synthesis of trisaccharide precursor 14. Optimization of

Influence of the cation in hypophosphite-mediated catalyst-free reductive amination

• Natalia Lebedeva,
• Fedor Kliuev,
• Olesya Zvereva,
• Klim Biriukov,
• Evgeniya Podyacheva,
• Maria Godovikova,
• Oleg I. Afanasyev and
• Denis Chusov

Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130

• dimethylamine and benzaldehyde promoted by hypophosphorous acid. Rationale of the current study: a) Our previous work [20]; b) this work. Comparison of KH2PO2 and NaH2PO2 under the optimal conditions. Control experiments. Experiments with D3PO2. Principal steps of the mechanism of the reductive amination with

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• condensation between 27 and the aldehyde afforded INT-A, which was activated by the CPA catalyst through hydrogen bonding interaction. The nucleophilic addition of isocyanide to Int-A produced INT-B bearing a stereogenic center. Subsequently, INT-B underwent intramolecular cyclization to generate axially

• non-central chiral compounds. a) Common types of chirality. b) Representative functional molecules bearing non-central chirality. Construction of planar chirality. Construction of axial chirality. Construction of inherent chirality. Construction of helical chirality. CPA-catalyzed enantioselective

Formal synthesis of a selective estrogen receptor modulator with tetrahydrofluorenone structure using [3 + 2 + 1] cycloaddition of yne-vinylcyclopropanes and CO

• Jing Zhang,
• Guanyu Zhang,
• Hongxi Bai and
• Zhi-Xiang Yu

Beilstein J. Org. Chem. 2025, 21, 1639–1644, doi:10.3762/bjoc.21.127

• annulation to construct the C ring (cyclohexenone ring), and an intramolecular SN2 reaction to build the D ring (five-membered ring) [15][16][17][18]. In 2013, Wallace and co-workers disclosed the second route for this molecule (Scheme 2B) [19], in which the five-membered ring B was formed by utilizing

• reaction in synthesis. Reported biologically active tetrahydrofluorenone-SERMs molecules. Reported synthesis routes to SERMs molecule VI. Lei’s synthesis of natural products of ent-kaurane diterpenoids (A), and natural products songorine, beyerene, garryine and steviol (B). Retrosynthetic analysis for the

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• a stabilization energy of ca. 17 kcal/mol. In the alternative hyperhomodesmotic reaction B, defined as 5 + 6 → 7 + 1, the formal ten-electron Hückel aromaticity of the imidazo[1,2-a]pyridine moiety (in blue) was preserved while the phenyl component was decomposed. The computed stabilization energy

• -phenylene moiety in the tetracyclic structure. Combination of reactions A and B in the form yields an average value of ⟨ΔEAB⟩ = −22.6 kcal/mol. A similar treatment of the separate components as outlined in reactions C and D shows a much lower stabilization energy for imidazo[1,2-a]pyridine 8 and a higher

• –phenylene distances. In addition, the ω = a–b–c–d dihedral angle between fluorophore 1 and the 1,4-phenylene ring is smaller than that calculated for the naked barium cation, but still shows a noticeable departure from coplanarity. The peculiar behavior of barium perchlorate with respect to naked Ba2

Transition-state aromaticity and its relationship with reactivity in pericyclic reactions

• Israel Fernández

Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125

• for the Diels–Alder cycloaddition reaction between isoprene and methyl acrylate catalyzed by Lewis acids. Bond distances are given in angstroms and NICS(3, +1) values in ppm. Comparative activation strain analyses (a) and energy decomposition analysis (b) of the Diels–Alder cycloaddition reaction

• reaction. (b) EDDB plots and NICS(3, +1) values for the carbonyl–ene reaction between 1-butene and acetaldehyde (left) and the analogous process catalyzed by AlCl3 (right). Comparative activation strain analyses (a) and energy decomposition analysis (b) of the carbonyl–ene reaction between 1-butene and

• acetaldehyde (black lines) and the analogous process catalyzed by AlCl3 (red lines) and projected onto the C···C bond-forming distance. AICD (a) and EDDB (b) plots for the transition state involved in the DGRT between ethene and ethane. Comparative activation strain analyses (a) and energy decomposition

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• wavelength 370 nm and 378 nm for (Sp)-6 and (Sp)-7, respectively. (A) UV, CD, PL, and CPL spectra of (Sp)- and (Rp)-6 in CHCl3 (1.0 × 10−5 M). (B) UV, CD, PL, and CPL spectra of (Sp)- and (Rp)-7 in CHCl3 (1.0 × 10−5 M). Excitation wavelength for CPL of both (Sp)-6 and (Sp)-7 = 300 nm. (A) CD spectrum of (Sp

• )-6 in CHCl3 (1.0 × 10−5 M), and the plot of the calculated rotatory strengths (TD-MN15/6-31G(d)//MN15/6-31G(d)). (B) CD spectrum of (Sp)-7 in CHCl3 (1.0 × 10−5 M), and the plot of the calculated rotatory strengths (TD-MN15/6-31G(d)//MN15/6-31G(d)). Molecular orbitals and simulated CPL profiles in the

• S1 states of (A) (Sp)-6 and (B) (Sp)-7 (TD-MN15/6-31G(d)). Synthesis of cyclic dimer (Sp)-6 and trimer (Sp)-7. Supporting Information Supporting Information File 26: Statement of computational methods, NMR and HRMS spectra, PL decay curves, glum charts, calculated ECD spectra, and cartesian

3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles

• Julia I. Pavlenko,
• Pavel A. Sakharov,
• Anastasiya V. Agafonova,
• Derenik A. Isadzhanyan,
• Alexander F. Khlebnikov and
• Mikhail S. Novikov

Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123

• method for the synthesis of 3-arylbenzo[4,5]thieno[3,2-b]pyrroles has been developed via pyrrole ring annulation to the aromatic benzo[b]thiophene system, using 3-arylazirines as a N‒C=C synthon. The reaction is catalyzed by Ni(hfacac)2 and proceeds through the azirine ring opening across the N=C3 bond

• heteroaromatic system have been reported to date. The formation of dihydrobenzofuro[3,2-b]pyrrole cycloadducts as by-products has been observed in the synthesis of aziridines by the transition metal-catalyzed reaction of benzofurans with 3-arylazirines [16]. This paper presents the use of azirines as annulation

• reagents for the preparation of 3-aryl-substituted benzo[4,5]thieno[3,2-b]pyrroles by the annulation of the 1H-pyrrole ring to the benzo[b]thiophene system (Scheme 1, reaction 6). The behavior of indoles as aza-analogs of the benzo[b]thiophenes under the identified catalytic annulation conditions is also

Chemical synthesis of glycan motifs from the antitumor agent PI-88 through an orthogonal one-pot glycosylation strategy

• Shaokang Yang,
• Xingchun Sun,
• Hanyingzi Fan and
• Guozhi Xiao

Beilstein J. Org. Chem. 2025, 21, 1587–1594, doi:10.3762/bjoc.21.122

• for the synthesis of tetrasaccharide 2; 3) [1 + 1 + 1] and [1 + 1 + 3] orthogonal one-pot assembly of pentasaccharide 3; 4) [1 + 1 + 1] and [1 + 1 + 1 + 3] orthogonal one-pot assembly of hexasaccharide 4. (A) Glycan structures of PI-88 and (B) retrosynthetic analysis of PI-88 glycan motifs 1–4. One

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• -31+G(d,p)//B3LYP/6-31+G(d,p) level of theory. Steady-state (a) absorption and (b) emission spectra of Pe–PTZ, Pe–PTZ(TPA), Pe–PTZ(TPA)2, and Pe–Ph–PTZ(TPA)2 in benzene at room temperature. The excitation wavelength was 420 nm for Pe–PTZ, Pe–PTZ(TPA)2, and Pe–Ph–PTZ(TPA)2, and 415 nm for Pe–PTZ(TPA

• . Microsecond transient absorption (a) spectra and (b) dynamics of Pe–PTZ(TPA)2 in benzene excited at 355 nm (5 μJ/pulse) and probed at 430 nm under nitrogen and oxygen conditions. Femtosecond-to-nanosecond transient absorption spectra and evolution-associated spectra (EAS) of Pe–PTZ(TPA)2 in benzene excited at

• (a, c) 350 nm (20 nJ/pulse) and (b, d) 420 nm (6 nJ/pulse) at room temperature. (a) Femtosecond-to-nanosecond transient absorption spectra and (b) evolution-associated spectra (EAS) of Pe–Ph–PTZ(TPA)2 in benzene excited at 350 nm (20 nJ/pulse) at room temperature. Summarized photophysical process of

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• substitution of an ortho-disubstituted benzamide (DiBA) increases the rotational barrier of the C–N and C–N/C–C concerted rotation (Figure 1a,b) [20]. The observation can be explained mainly by the double-bond nature of the chalcogen amide C–N bond, which is attributed to a zwitterionic resonance structure of

• various fields, such as functional materials, biological probes, and drugs. a) Structural features of DiBA. b) Resonance structure of the amide moiety of DiBA. c) Molecular form and protonated structure of ortho-disubstituted benzamidine. Rotational barriers of 2-bromo-N,N,6-trimethylbenzimidamide and its

• protonated form calculated by the DFT method. Comparison of VT-NMR spectra of a) amidine 1 and b) its trifluoroacetate salt 1-H+ in DMSO-d6 (400 MHz). Separation and isolation of amidine E/Z isomers by RP-HPLC. The mobile phase contained CF3CO2H to protonate the amidine moiety. Kinetic analysis of the

Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins

• Juliana V. Petrova,
• Varvara T. Tkachenko,
• Victor A. Tafeenko,
• Anna S. Pestretsova,
• Vadim S. Pokrovsky,
• Maxim E. Kukushkin and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118

• '-disubstituted ureas were initially reacted with oxalyl chloride to form imidazolidinetriones 1a,b, which were then added to an iminophosphorane formed in situ from an aryl azide and triphenylphosphine. As a result of the aza-Wittig reaction, 5-iminohydantoins 2a–i were then used as dipolarophiles in the 32CA