Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• , base, solvent, and reagent equivalents to optimize the alkylation reaction for both bromides 4 and 5 (Table 1 and Table 2). For Ni(II) complex of [2.3.5.6F]TfMePhe (6), firstly we screened different inorganic and organic bases (Table 1, entries 1–3) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was

• identified as optimal delivering a yield of alkylated complex of 60% (Table 1, entry 4). With DBU as base different solvents differing in polarity have been tested. At room temperature, acetonitrile proved best and increased the yield to 88% (Table 1, entry 11). Lowering the temperature to 0 °C led to a

• final yield of 94%. At these conditions (DBU, MeCN and 0 °C) the base and bromide equivalents were further modified but no further increase in yield could be achieved. Thus, 1.5 equiv DBU with 1.05 equiv alkyl bromide in MeCN at 0 °C have been identified as optimal conditions for the Ni complex

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• ]. In some cases, the addition of a non-nucleophilic base is needed to neutralize the HCl generated during the reaction (Scheme 20). For example, Yu et al. demonstrated that the reaction yield could be significantly increased when the reaction was performed in the presence of one equivalent of DBU [62

• ]. They argued that organic bases such as DBU are superior than inorganic bases in improving the yields, probably because of the low solubility of the last ones in the reaction system. In the same way, other bases such as DABCO [64], DBU [66], and TMG (1,1,3,3-tetramethylguanidine) [65][67] were shown to

• (I)) by reducing the suitable salts (containing Au(III), Co(II), Fe(III), and Ni(II), respectively) at the beginning of the catalytic cycle. The metal in its reduced species (depicted in Scheme 23) activates the C–H bond of the alkyne. After this activation step, a weak base (like DBU, TMG, or even

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• organic base such as tetramethylethylenediamine (TMEDA) or 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) [28]. Our initial attempt to apply this method was as follows: A reaction mixture of 9,10-ANTH(Br)2, 10 equiv BnFI, and 10 equiv DBU dissolved in acetone was illuminated with a blue LED for 20 h (see

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• -1,3-dimethylimidazolinium hexafluorophosphate (ADMP) in the presence of DBU in acetonitrile. This one-pot process enables sequential diazotization and cyclization, leading to the formation of two or three C–N bonds under extremely mild conditions, with excellent tolerance for various functional groups

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• in machine-assisted oligosaccharide synthesis. 4-Acetoxy-2,2-dimethylbutanoyl (ADMB) esters were reported by Ensley and co-workers [108] having similar properties with the pivalate group. The facile removal of the C-2-ADMB group with a catalytic quantity of diazabicycloundecane (DBU) in methanol at

Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles

• Zi-Ying Xiao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21

• such as DABCO, DBU, triethylamine, and K2CO3 also resulted in the significant reduction of the yields. Therefore, the reaction of MBH nitrile of isatins and arylamines can be simply carried out in toluene at room temperature in the presence of a catalytic amount of DMAP. With the optimized reaction

Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

• John M. Halford-McGuff,
• Thomas M. Richardson,
• Aidan P. McKay,
• Frederik Peschke,
• Glenn A. Burley and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

• equiv), DMF, air, rt, 2 h. (iv) Pd(dtbpf)Cl2 (10 mol %), 2-acetylthiophen-3-ylboronic acid (1.2 equiv), K3PO4 (2.0 equiv), iPrOH/H2O 3:4, N2, 85 °C, 16 h. (v) Pd(dtbpf)Cl2 (2.0 mol %), 1-naphthylzinc bromide (1.2 equiv), THF, N2, 45 °C, 16 h. (vi) Cu(OAc)2·H2O (30 mol %), B(OH)3 (2.0 equiv), DBU (2.0

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• section and complete set of NMR spectra. Funding Financial support was provided by the University of Siegen. R.S. is grateful to the House of Young Talents (University of Siegen) and the Stiftung Nagelschneider for the Ph.D. fellowships. T.J.B.Z. thanks the Deutsche Bundesstiftung Umwelt (DBU) for a Ph.D

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

• compound 57 was obtained by treating hypervalent iodine salt 56 with NaNO2 in the presence of DBU as the base (Scheme 23). This salt was also studied for the arylation of sulfur, oxygen, and carbon giving good yields of corresponding products [74]. O-Arylation Arylation of oxygen is a significant chemical

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

• Yuta Kabumoto,
• Eiichiro Yoshimoto,
• Bing Xiaohuan,
• Masato Morita,
• Motohiro Yasui,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233

• Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan 10.3762/bjoc.20.233 Abstract Treatment of various (R)-N-(2,2,3,3-tetrafluoropent-4-en-1-ylidene)-1-phenylethylamine derivatives with 2.4 equiv of DBU in toluene at room temperature to 50 °C for 24 h led to

• the NOESY spectrum of the imine (R)-16c, the stereochemistry of the imines (R)-16 was determined as E [36]. Among the imines thus obtained, (R)-16b was used to investigate the optimum reaction conditions (Table 1). Treatment of (R)-16b with 1.2 equiv of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) in THF

• diethyl ether, toluene, hexane, and cyclohexane, (S)-20b was obtained in 30% to 40% yield and significant amounts of unreacted substrate were still observed, although formation of the byproduct 22b could be generally suppressed. We also examined the reaction using other bases instead of DBU. As shown in

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• , entry 10). Other bases like NaOMe, triethylamine, DBU, DMAP, sodium acetate, or DABCO also produced the product in moderate to good yields (42–87%) when used in excess (Table 1, entries 11–16). Interestingly, the reaction did not proceed in the presence of pyridine as a base (Table 1, entry 17). Finally

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• fragment in the side chain were investigated. It was shown that the studied process leads to substituted tetronic acids bearing a pyrrolidinone moiety. The application of 1,1′-carbonyldiimidazole and DBU is necessary for implementation of the considered reaction. Based on the performed research a general

• only in the presence of a strong base (DBU). Results and Discussion The starting allomaltols 3 bearing an amide fragment in the side chain were prepared by reaction of dihydropyranones 5 with appropriate amines 6 applying the previously described method [33][34] (Scheme 2). At first, amide 3a was

• bases under conditions described earlier for corresponding hydrazides. So, among the employed basic agents (Et3N, DABCO, DBU, DMAP, K2CO3, AcONa) only in the case of DBU the expected recyclization was observed and the target product 4a was obtained in 15% yield. In order to enhance the yield of compound

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• possibly due to the higher steric congestion by the selection of the other CO2Et moiety. As shown in entries 8 or 9 in Table 4, it was proved that the usage of tetramethylguanidine (TMG) or DBU as the base provided a different stereoisomer as the major component. For the confirmation of its stereostructure

• , the isolated inseparable mixture of anti,syn-7a and -7b by the reaction of 2b and diethyl malonate was treated with an equimolar amount of DBU in DMSO (rt, 3 h) to furnish products which were identical to the ones obtained in entries 8 or 9 (Table 4). The relative stereochemistry of the isomerized

From perfluoroalkyl aryl sulfoxides to ortho thioethers

• Yang Li,
• Guillaume Dagousset,
• Emmanuel Magnier and
• Bruce Pégot

Beilstein J. Org. Chem. 2024, 20, 2108–2113, doi:10.3762/bjoc.20.181

• conditions (Table 1, entry 9). Other organic nitrogenous bases were tested (Table 1, entries 10–12). Et3N gave nearly the same result, while DBU seemed less efficient. The use of the inorganic base K2CO3 resulted in poor outcomes. With the optimized conditions in hand, a scale-up was successfully performed

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• diazo precursor. To achieve this, cholesterol was first esterificated using 2-(4-methoxyphenyl)acetic acid and DCC. The resulting arylacetic ester 12 was then reacted with 4-acetamidobenzenesulfonyl azide (p-ABSA) and DBU in anhydrous acetonitrile to yield the diazo compound 13 in 22% yield. The carbene

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• afforded higher yields and shorter reaction times compared to standard stirring conditions with DBU. When employing substrates bearing secondary benzylic sites in the reaction conditions, the difluorinated products were observed exclusively in high yields. In 2016, Britton and co-workers reported a method

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• (Table 1, entry 2). It should be noted that application of strong base DBU led to the complex mixture of products (Table 1, entry 5). At the same time basicity of NaHCO3 is not enough for realization of the studied recyclization and in this case the starting hydrazone 3b was isolated unchanged (Table 1

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• example, methyl acetoacetate (2a) possesses one CH-acidic methylene carbon which can be deprotonated in equilibrium by weak organic bases, such as triethylamine, piperidine or DBU, under thermodynamic conditions. Dimethyl acetone-1,3-dicarboxylate (3a) contains even two reactive methylene groups which can

• of DBU afforded furo[3,2-b]chromen-9-one 36a in 32% yield. Based on this observation, the two-step one-pot reaction of ketoamides 34a–f with 3-halochromones 15a–c was studied which afforded furo[3,2-b]chromen-9-ones 36a–f, albeit, in only low to moderate yields (Scheme 19) [41]. The formation of

• attack of the sulfur to the bromide (intermediate AC) and subsequent ring-cleavage. In most reactions, DBU was employed as the base. In case of products derived from N-unsubstititued 3H-indole-2-thiones (R3 = H), employment of potassium carbonate proved to be advantageous. Similarly to the formation of

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• Foundation (DBU, Ph.D. fellowship to T.J.B.Z., grant number 20022/028). M.S. is grateful to the Chemical Industry Funds for a Kekulé fellowship.

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• %). Under these conditions, the 5-endo-dig cyclization leading to the target spirobutenolide 2a proceeded rather slowly (about 25% conversion per day). However, an attempt to accelerate the reaction by using a stronger base (DBU) resulted in side processes with the formation of unwanted impurities, whereas

• monitor the progress of the reaction and the formation of the OH-insertion product 14. An attempt to carry out the second step in a one-pot format with the addition of 1.2 equiv of base (DIPEA or DBU) was unsuccessful and the formation of the spirocyclic product was not observed. Replacing DCM with a more

• polar solvent, acetone, significantly accelerated the cyclization process. Thus, one to three days were required to complete the 5-exo-tet cyclization process in the acetone/DBU system. The results of the syntheses carried out with the participation of various DAS 1 to obtain spirocyclic THFs are

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• of stereoisomers in 2:1 ratio. After isolation by distillation, 2,3-dibromo-1,1,1,4,4,4-hexafluorobutane (2) was characterized by 1H, 19F, 13C NMR and mass spectra. We studied the reaction of dibromoalkane 2 with various bases such as DBU, Hünig’s base (iPr2NEt), and potassium hydroxide (Table 1). In

• ca. 11 Hz for (E)-isomer). The best results were obtained in Et2O with Hünig’s and DBU bases (Table 1, entries 2 and 3), but unfortunately in these cases the product olefins could not be separated from Et2O. Therefore, we decided to use high-boiling diglyme instead of ether. The reaction of a butane

• 2 with one equivalent of DBU (Table 1, entry 4) led to the same results as for the Hünig’s base (Table 1, entry 1). The use of two equivalents of DBU (Table 1, entry 6) led to the complete conversion of the initial substrate, but the selectivity of the reaction was significantly reduced in this case

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• derivatives (Scheme 1b) [21]. In the course of this reaction 20 mol % of Pd catalyst, 50 mol % of phosphine ligand and 30 equiv of DBU as base were used to afford the desired fluoranthene derivatives. 1-Naphthylboronic acid and 1,2-dibromobenzene in the presence of Pd2(dba)3 (20 mol %) and PCy3 (80 mol

• %) using again a large excess of DBU base (7 equiv) also allowed to prepare unsubstituted fluoranthene in 87% yield (Scheme 1c) [22]. The reaction of naphthol with aryl bromides followed by nonaflation and intramolecular C–H activation for the access to fluoranthenes has also been reported [23]. Most of

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• , did not provide any improvement of the reaction outcome as only traces of the intermediate 3a were obtained (entry 3, Table 1). Switching to DBU as the base under these conditions, gave intermediate 3a in 35% yield (entry 4, Table 1). In fact, DBU was previously shown by Wannberg and Larhed to be an

• . However, we only obtained traces of intermediate 3a (entries 5 and 6, Table 1). A slight improvement of the yield of the intermediate 3 was obtained when using DBU in dioxane, which gave 3a in 42%, but only traces of the target DBDAP were observed (entry 7, Table 1). The difficulty encountered in the

• formation of DBDAP, prompted us to test alternative CO surrogates. When the reaction was performed using Co2(CO)8 (0.3 equiv) in the presence of DBU, the intermediate 3a was isolated in 35% yield, but again no DBDAP 4 was obtained (entry 8, Table 1). Formic acid, an effective CO surrogate [20][22], was also