Palladium-catalyzed benzocyclization reactions of quinoline-2-carboxamides via sequential C–H/N–H functionalization

• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2026, 22, 905–914, doi:10.3762/bjoc.22.71

• University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan 10.3762/bjoc.22.71 Abstract A novel benzocyclization protocol has been developed for the synthesis of quinoline-fused lactams by palladium-catalyzed sequential C–H/N–H functionalization of quinoline-2-carboxamides and 1,2-dihaloarenes. The reaction

• metal affinity [9][10]. It is therefore expected that annulation of the amide moiety in quinoline-2-carboxamides would extend their functionality as biologically active structures, ligands, and extractants. Transition-metal-catalyzed coupling reactions are crucial for constructing carbon–carbon and

• This study explored a novel palladium-catalyzed C–H/N–H activated annulation reaction for the synthesis of quinoline-fused lactams. The annulation reaction afforded the desired products in up to 83% yield. The reaction displayed broad tolerance for various substituents. Moreover, the reaction

Cascade transformation of 2-(diazoacetyl)-2H-azirines to 2-aroyl-3-hydroxy-1H-pyrroles via condensation with aromatic aldehydes

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2026, 22, 897–904, doi:10.3762/bjoc.22.70

• [4.1.0]heptan-5-one derivative. The acid-catalyzed transformation of which leads to 2-aroyl-3-hydroxy-1H-pyrroles. Keywords: azirines; condensation; cyclization; diazo compounds; pyrroles; Introduction Diazo compounds play a significant role in the synthesis of heterocyclic compounds, which explains

• bicyclic intermediate 4. This acid-catalyzed transformation leads to 3-hydroxy-2-aroyl-1H-pyrroles 5 (Scheme 1). To the best of our knowledge, only few examples of such compounds have been so far reported [23][24]. Results and Discussion A test reaction of 2-(2-diazoacetyl)-3-phenyl-2H-azirine (1a, R = Ph

• proceeds via an azirinyl-substituted β-hydroxy-α-diazocarbonyl compound, which undergoes intramolecular cyclization involving the hydroxy group and the C=N bond of azirine, leading to the formation of a bicyclic intermediate, a 4-diazo-2-oxa-7-azabicyclo[4.1.0]heptan-5-one derivative. Acid-catalyzed

Chiral cyclopropenimine-catalyzed enantioselective Michael reactions of phenol and benzofuran-derived α,β-unsaturated pyrazolamides with benzophenone-imine of glycine esters

• Ya Bai,
• Xue-Ying Wang,
• Si-Kai Zhu,
• Yan-Ting Shen,
• Sheng-Yong Zhang and
• Ping-An Wang

Beilstein J. Org. Chem. 2026, 22, 888–896, doi:10.3762/bjoc.22.69

• series of 3-substitued glutamic acid esters in high yields and diastereoselectivities through DBU-catalyzed Michael additions of benzophenone-imine of glycine ester and α,β-unsaturated esters which derived from phenols and benzofurans under mild conditions [5][6]. The chiral 3-aryl-substituted glutamic

• -disubstituted glutamic and pyroglutamic acid esters by this protocol are underway. Experimental General procedure for the CSB-1-catalyzed Michael addition of compounds 2 and 5 To 2a (1.0 mmol) and 5a (1.0 mmol) in EtOAc (10.0 mL) was added CSB-1 (0.2 mmol) and the mixture was stirred at rt for 18 h. After the

• dried over Na2SO4 and the solvent was evaporated under vacuum. The residue was purified by flash column chromatography to afford pure 7d as a white solid. Bioactive molecules with benzofuran and pyroglutamic acid motif. CSB-1-catalyzed Michael reactions of α,β-unsaturated compouds with glycine

Diastereodivergent electrophilic trapping of α-boryl lithium derivatives

• Tereza Pavlíčková,
• Noam Orbach and
• Ilan Marek

Beilstein J. Org. Chem. 2026, 22, 882–887, doi:10.3762/bjoc.22.68

• electrophile PhMe2SiCl did not alter the selectivity of the transformation, yielding 6b as a single diastereomer (Scheme 3). The relative configuration of 6b was determined by X-ray analysis of the osmate ester 7b, derived from osmium-catalyzed dihydroxylation (Scheme 3) [38], and the other products were

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• arrangement of the two oxindole units and the central piperazine ring. Reaction of isatin (1) with ʟ-proline (7) [16][17]. Condensations of isatin with primary [18] and N-methylated diamines [19]. Catalyzed synthesis of the bis[spiro(quinazoline-oxindole)] derivative 21 [20]. (a) Ethylenediamine (0.5 equiv

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

• from imino esters, catalyzed by chiral Cu(I,II) and Ag(I) complexes, are widely used. Reactions using α-amino acids proceed, in most cases, without the use of catalysts, with high yields and high stereoselectivity. Electrophilic alkenes of various structures, (hetero)aromatic olefins and benzofulvenes

• , the importance of the formation of azomethine ylides from amino esters, amino acids, imine derivatives, aziridines or other substrates was emphasized. A review [26] demonstrates metal-catalyzed as well as metal-free asymmetric and racemic transformations of imino ethers upon interaction with various

• development of this method is also presented. Review Imine derivatives as precursors of azomethine ylides Azomethine ylides based on iminoesters In 2002, Zhang and co-workers described a highly enantioselective Ag(I)-catalyzed (3 + 2) cycloaddition of azomethine ylides from α-(arylimino)esters using AgOAc as

Synthesis of depressin, cryptomeridiol and 4-epi-cryptomeridiol enabled by a terpenoid chiral pool-producing platform

• Yao Kong,
• Tao Wang,
• Chen Wang,
• Pengcheng Zhang,
• Yuanning Liu,
• Kaibiao Wang,
• Fen Liu,
• Hongli Jia and
• Zhengren Xu

Beilstein J. Org. Chem. 2026, 22, 683–690, doi:10.3762/bjoc.22.53

• be widely used as popular starting materials. It is interesting to note that for the biosynthesis of the complex terpenoid skeletons, Nature has evolved a straightforward strategy by the terpene cyclase-catalyzed cyclization of linear oligoprenyl pyrophosphates, which are generally derived from the

Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions

• Egor N. Boronin,
• Svetlana E. Kaurkina,
• Milena M. Svetlakova,
• Anton S. Bolshakov,
• Maxim V. Arsenyev,
• Vasilii F. Otvagin,
• Alexey Yu. Fedorov,
• Timothy Noël and
• Alexander V. Nyuchev

Beilstein J. Org. Chem. 2026, 22, 662–671, doi:10.3762/bjoc.22.50

• -catalyzed [8], organic photocatalyst-mediated, or electrochemical transformations [9], and also include continuous-flow processes [6][10][11][12][13]. Given that photocatalytic reactions align with the principles of green chemistry, particularly energy efficiency and the use of catalytic pathways, such

Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• 289, 9000 Gent, Belgium 10.3762/bjoc.22.48 Abstract The first NHC–Cu-catalyzed decomposition of formic acid (FA) is reported. In the presence of PhSiH3, only hydrogen is generated while CO2 is captured by a silane species. The decomposition of an equimolar mixture of FA and an amine provided an

• performances than copper salts, even with lower catalyst loading and under milder conditions [49][50][51]. Based on this background, the first potential formic acid dehydrogenation catalyzed by NHC–Cu complexes (Figure 1) was investigated. Results and Discussion We have shown that the reaction of [Cu(OH)(IPr

• experiments were carried out (Scheme 2). By reacting FA and PhSiH3 (1:1 molar ratio) in the presence of 10 mol % of 1a, in deuterated toluene at room temperature under D2 atmosphere (1 atm), no H–D scrambling was observed (Scheme 2a). Furthermore, the 1a-catalyzed reaction of FA labeled at the acidic position

Regioselective approach to 5-arylsulfonylisoxazoles and their antimicrobial activity

• Artem S. Sazonov,
• Dmitry A. Vasilenko,
• Denis V. Porfiriev,
• Yuri K. Grishin,
• Rimma A. Gazzaeva,
• Alisa P. Chernyshova,
• Maxim A. Kryakvin,
• Anna A. Baranova,
• Vera A. Alferova and
• Elena B. Averina

Beilstein J. Org. Chem. 2026, 22, 592–602, doi:10.3762/bjoc.22.45

• 4-unsubstituted isoxazoles with various aryl substituents in position 3 [24][25] (approach B). One example describes the Ru-catalyzed reaction of nitrile oxide with alkynyl sulfone providing 5-sulfonylisoxazole with high regioselectivity [26] (approach C). Despite the widespread application of

Continuous-flow carbonyl hydrogenation under subatmospheric to atmospheric hydrogen pressure enabled by robust heterogeneous Pt–Fe catalysts

• Hiroyuki Miyamura,
• Ryosuke Kajiyama,
• Shun-ya Onozawa,
• Yoshihiro Kon and
• Shū Kobayashi

Beilstein J. Org. Chem. 2026, 22, 575–582, doi:10.3762/bjoc.22.43

• might be reduced by NaBH4 faster than FeCl2 in the solution phase, and the generated Pt(0) nanoparticles are stabilized by DMPSi surface. The reduction of FeCl2, which is usually more difficult to achieve can be catalyzed on the surface of Pt(0) nanoparticles and the formed Fe species are deposited and

Kinetic resolution of racemic planar-chiral vinylcymantrenes by molybdenum-catalyzed asymmetric metathesis dimerization

• Haruna Imazu,
• Hitoshi Izu,
• Yasuhiro Ohki and
• Masamichi Ogasawara

Beilstein J. Org. Chem. 2026, 22, 568–574, doi:10.3762/bjoc.22.42

• ) reaction catalyzed by a chiral molybdenum-alkylidene precatalyst. The Mo/(R)-L1 precatalyst promoted the AMD/KR reaction of rac-1a (R = Br) to give (E)-(R,R)-2a of 99% ee together with unreacted recovered (S)-1a of 45% ee at 37% conversion. The diastereoselectivity of this reaction was excellent with

• ], racemic 5a–c were prepared in the same ways starting with rac-3. Vinylcymantrene substrates rac-1a–c were obtained in 68–79% yields by the Wittig methylenation of rac-5a–c. The moderate yields could be attributed to the volatility of rac-1a–c. Molybdenum-catalyzed asymmetric metathesis dimerization (AMD

• metathesis dimerization of (R)-1a preferentially, and the most of antipodal (S)-1a was recovered intact. In general, vinylcymantrenes are much less reactive than analogous vinylferrocenes in the molybdenum-catalyzed AMD [30], and the conversion tends to be lower. Only 25% conversion was attained in the

Experimental and DFT studies on the regioselective methanolysis of 5-azido-9-oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers

• İlknur Polat,
• Selçuk Eşsiz and
• Emine Salamci

Beilstein J. Org. Chem. 2026, 22, 547–556, doi:10.3762/bjoc.22.40

• , pharmaceutical compounds, and chiral ligands. The Lewis acid-catalyzed ring-opening reaction of cyclohexene oxide by MeZH (Z = O, S, and NH) is well known [20]. However, studies on large-sized bicyclic epoxides remain relatively limited in the published literature. In our previous study, we performed the ring

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• almost quantitative (see Supporting Information File 1, Figures S13 and S14). To gain more information about the course of the photoreaction and sequential formation of intermediates, the photoreaction of 1f, catalyzed by flavin 4, was investigated with in situ 19F NMR-spectroscopic analysis. During the

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

• towards 113 upon acidic treatment and TBDMS-protection. Reduction, cleavage of the silyl-protecting groups and acetylation led to tetrahydropyran 114. Lewis acid-catalyzed C-allylation, cross metathesis, basic cleavage of the acetate motifs and transesterification enabled the DBU-induced isomerization of

• . Scaling up the Grubbs metathesis of the first route (Scheme 10, step (h) i.) led to an increasement of dimer yield derived from cross metathesis reactions. Therefore, by the replacement with the Rh(I)-catalyzed cyclization performed herein, this drawback is circumvented and the reactions were performed

• to afford 154. Allylation and acidic deprotection led to diol 156 in excellent yields. Next, Au(I)-catalyzed cyclization and reduction led to tetrahydropyran 157, which was TBDMS-protected subsequently. The cross metathesis of 158 and 162 (obtained from ʟ-glutamic acid) yielded 159 in 81%. After

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• -hydroxyphenyl)calix[4]pyrrole, commonly referred to as phenoxycalix[4]pyrrole (PCP). It was first reported in 1999 by two independent research groups, Floriani et al. and Sessler et al., via the acid-catalyzed condensation of pyrrole with p-hydroxyacetophenone [17][18]. PCP and its derivatives were first known

Recent advances in the stereoselective synthesis of distal biaxially chiral molecules

• Fanxing Zhou,
• Chen Zhang,
• Lingyu Sun,
• Yiyun Fang,
• Siming Zheng,
• Lina Hu,
• Mengyang Shen,
• Zhen Zhao,
• Wei Xu,
• Yunqiang Sun and
• Zi-Qiang Rong

Beilstein J. Org. Chem. 2026, 22, 461–479, doi:10.3762/bjoc.22.34

• , Hayashizaki, and Ito reported a highly stereoselective asymmetric cross-coupling reaction of 2-methylnaphthylmagnesium bromide with bromonaphthalene, catalyzed by a nickel complex with ferrocenylphosphine as the ligand, successfully synthesizing biaxially chiral molecules, namely 1,1':5',1"- and 1,1':4',1

• demonstrated that such one-step catalytic approaches not only streamline the synthesis of structurally complex biaxial molecules but also open new avenues for their applications in catalysis, drug discovery, and functional materials. In 2004, Shibata and co-workers reported a novel iridium-catalyzed asymmetric

• , transition-metal-catalyzed approach for the synthesis of helically chiral polyaryl compounds with well-defined sequences of axial chirality. Using this method, they successfully obtained pentaaryl 6 (Scheme 1b) and nonaryl derivatives (not shown) bearing four and eight consecutive chiral axes, respectively

Cone p-aminocalix[4]arenes enriched with ‘clickable’ alkyne or azide functionalities

• Ilia Korniltsev,
• Vasily Bazhenov,
• Alexander Gorbunov,
• Dmitry Cheshkov,
• Stanislav Bezzubov,
• Vladimir Kovalev and
• Ivan Vatsouro

Beilstein J. Org. Chem. 2026, 22, 399–415, doi:10.3762/bjoc.22.28

• conversion into diverse 1,4-disubstituted 1,2,3-triazole units under CuAAC (copper(I)-catalyzed azide–alkyne cycloaddition) ‘click’ conditions [70][71][72][73]. The first implementation of the CuAAC approach for calixarene modification was published shortly after its introduction into chemistry in general

• to be not bulky enough to protect the alkyne from a Raney-Ni-catalyzed reduction by gaseous hydrogen, as a trial hydrogenation of the nitrated/propargylated calix[4]arene 11 resulted in only trace amounts of the desired p-aminocalix[4]arene 18 among numerous other reaction products. Due to this, a

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• ]. Such activation has enabled a wide array of transformations, including metal-catalyzed cross-couplings via oxidative addition into the amide C–N bond (Scheme 1c) [32][33][34][35][36], and transition-metal-free acyl substitutions facilitated by improved leaving-group ability [37][38][39][40]. Although

• secondary and tertiary amides with octanol catalyzed by CeO2, utilizing the advantage of its cooperative acid–base functionalities (Scheme 2) [46]. Under the optimized conditions, N,N-dimethylbenzamide (3) and N,N-diethylbenzamide (4) were smoothly converted to octyl benzoate (1) in 93% and 95% yield

• intermediate E, the carboxylic acid is formed, regenerating the acidic and basic surface sites of the Nb2O5 catalyst. In 2020, Mashima et al. reported an intriguing accelerating effect of potassium alkoxides on the manganese-catalyzed esterification of tertiary amides (Scheme 4) [48]. They found that potassium

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• ]. In 2018, Kota and Sreevani prepared spirobarbiturates via a Mo(CO)6-catalyzed intermolecular [2 + 2 + 2] cycloaddition of propargyl halides with dipropargylbarbituric acid [24]. Almeida and colleagues described the formation of spiroindoline barbiturates via thermal rearrangement of 2,1-benzisoxazole

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• disrupting the aromatic core, such as electrophilic and nucleophilic aromatic substitutions, transition metal-catalyzed cross-couplings [11], and C–H functionalizations [12]. Taken together with their natural abundance, these transformations have established arenes and heteroarenes as versatile synthetic

• sequence elegantly illustrates how η4-coordination can orchestrate multistep bond construction. Finally, η4-bound intermediates have been proposed as intermediates in catalytic transformations – most notably in Chirik’s molybdenum-catalyzed arene hydrogenations [106][107] – highlighting the emerging

A mild and atom-efficient four-component cascade strategy for the construction of biologically relevant 4-hydroxyquinolin-2(1H)-one derivatives

• Dmitrii A. Grishin,
• Kseniia I. Sharkovskaia,
• Ilya G. Kolmakov,
• Daria A. Ipatova,
• Rostislav A. Petrov,
• Nikolai D. Dagaev,
• Dmitry A. Skvortsov,
• Maria G. Khrenova,
• Valeriy V. Andreychev,
• Sergei A. Evteev,
• Yan A. Ivanenkov,
• Roman L. Antipin,
• Olga А. Dontsova and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2026, 22, 244–256, doi:10.3762/bjoc.22.18

• reactions catalyzed by diverse agents (Scheme 1). For instance, in 2013, Shi et al. described a three-component reaction involving 4-hydroxyquinolin-2(1H)-one, an aromatic aldehyde, and Meldrum’s acid, catalyzed by ʟ-proline under heating [37]. In the same year, Kurosh Rad-Moghadam and co-workers developed

• a related protocol operating at room temperature using the ionic liquid [Bmim]HSO4 as a catalyst, expanding the scope to include aliphatic aldehydes [38]. Later, in 2017, Esmayeel Abbaspour-Gilandeh et al. reported a modified variant of this transformation under solvent-free heating, catalyzed by

• in the reaction mixture [44][45]. Previous studies have reported the synthesis of compounds structurally related to our targets – 4-aryl-4,6-dihydro-2H-pyrano[3,2-c]quinoline-2,5(3H)-diones – via multicomponent reactions catalyzed by various agents (Scheme 1) [37][38][39]. These one-pot reactions

Screwing the helical chirality through terminal peri-functionalization

• Devesh Chandra,
• Sachin and
• Upendra Sharma

Beilstein J. Org. Chem. 2026, 22, 205–212, doi:10.3762/bjoc.22.14

• catalysts [33]. A domino reaction was developed, beginning with a PPS L2-catalyzed Michael addition of phosphine oxides 7 to nitro-substituted oxa[5]helicenes 6, followed by a copper-promoted aromatization. This sequence efficiently produced phosphorus-containing oxa[5]helicene derivatives 8 in high yields

• corresponding amine followed by N-tosylation, providing product 10 in 63% yield without altering the enantiomeric excess (Scheme 4). Additionally, product 8g was converted into the chiral phosphine ligand 12 while fully preserving its helical chirality and successfully applied in palladium-catalyzed

• [5]helicenes. Scale-up synthesis and post-synthetic application of chiral helical product 8g. Post-synthetic transformation of product 8g to chiral phosphine ligand 12 and its application in Pd-catalyzed reactions. Acknowledgements The authors acknowledge the CSIR-IHBT, Palampur for providing

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• oxidation of ketones includes C‒C-bond cleavage, and carboxylic acids are predominantly formed. This can be achieved by the treatment of acyclic ketones with hypohalites [13], in the nitroarene-catalyzed oxidation with oxygen under basic conditions [14] or by the use of hypervalent iodine compounds (Scheme

• available reagents is an important task. Recently, we have developed a copper(I)/rhodium(II)-catalyzed method toward two types of regioisomeric 2,5-dihydrothiophenes 1 and 4, containing an acetyl group [50]. In this work, to evaluate the synthetic utility of these compounds (the scope is presented at page

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• -Petersburg 199034, Russia 10.3762/bjoc.22.5 Abstract New highly electrophilic gem- and spiro-activated trichloromethylnitrocyclopropanes were obtained by the Michael-initiated ring closure (MIRC) reaction of 1-bromo-1-nitro-3,3,3-trichloropropene with linear and cyclic CH-acids catalyzed by bases