Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• zinc cations to align 1.1 through the formation of hydrogen-bonded coordination complexes. Thus, when a single crystal of the [Zn(bpe)2(H2O)4](NO3)2·8/3H2O·2/3bpe complex was exposed to UV irradiation (dark blue phosphor lamps, λ = 350 nm) for 25 h, only 46% conversion to 1.2 was observed via 1H NMR

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• such as zinc as proposed by Furuyama et al. [35]. In this way, the authors have developed a series of phthalocyanin zinc complexes with electron-rich sulfur atoms at the non-peripheral positions of the phthalocyanin ring. This functionalization allows the destabilization of the highest occupied

• this review hitherto. This singlet oxygen is generated by the energy transfer from the excited state of the phthalocyanin zinc complexes to molecular oxygen, allowing the oxidation of the N-phenyltetrahydroisoquinoline 21 into a reactive iminium intermediate that subsequently couples with nucleophiles

• to give 22. In a same manner, Opatz et al. have shown that zinc phthalocyanins can catalyze oxidative cyanation reactions of tertiary amines 23, yielding α-aminonitriles 24 under continuous-flow conditions [36]. This reaction proceeds through the excitation of zinc phthalocyanin by near-infrared

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• cooperative intermolecular forces. Zinc ion-induced coordination with the macrocycle and a terpyridinium derivative enabled orthogonal polymerization, as revealed by 1H NMR, DLS, and TEM techniques. In addition, viscosity measurements showed a transition from oligomers to polymers at the critical

• polymers (Scheme 1). The terpyridyl group and the pyridinium cation in the AB-type monomer G2 each function as a “sticker” to enable supramolecular polymerization in the presence of the macrocyclic component and zinc ions. The driving force for the recognition involves multiple cooperative interactions

• coordinating metal ions. In such supramolecular polymers, orthogonal host–guest and coordination interactions are responsible for polymerization. Host–guest complexation and zinc coordination When forming supramolecular polymers, an AB-type monomer, i.e., the guest G2, is supposed to interact with the

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• reaction was also fruitful to obtain 1,2-dihydroisoquinolines 25 starting from 2-alkynylbenzaldehydes, primary amines and allylic or benzyl bromide, in the presence of zinc and using the combination of Mg(ClO4)2/Cu(OTf)2 as catalyst. The use of a mixture THF/DCE 1:20 as solvent was mandatory, because THF

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• synthesis of tripeptides incorporating new fluorinated heterocyclic hydrazino acids, based on the tetrahydropyridazine scaffold is described. Starting from simple fluorinated hydrazones, these non-proteinogenic cyclic β-amino acids were easily prepared by a zinc-catalyzed aza-Barbier reaction followed by an

• ,anti. Then, hydrazones 3 were reacted with zinc and methyl 2-(bromomethyl)acrylate (4). This aza-Barbier reaction was performed in a biphasic medium (THF/aqueous solution of saturated NH4Cl) to avoid the formation of the α-methylene-γ-lactam obtained by intramolecular cyclization of the zinc amide on

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• aza-heterocycles were synthesised in good yields. The authors proposed a mechanism for the fluorocyclisation reactions (Scheme 6), which relies on the activation of the fluoro-iodane reagent 12 with the zinc catalyst. The activation enables better orbital overlap to occur with the π bond of the alkene

Multicomponent synthesis of α-branched amines using organozinc reagents generated from alkyl bromides

• Baptiste Leroux,
• Alexis Beaufils,
• Federico Banchini,
• Olivier Jackowski,
• Alejandro Perez-Luna,
• Fabrice Chemla,
• Marc Presset and
• Erwan Le Gall

Beilstein J. Org. Chem. 2024, 20, 2834–2839, doi:10.3762/bjoc.20.239

• Paris, France 10.3762/bjoc.20.239 Abstract The use of alkylzinc bromides in the multicomponent Mannich reaction is described. Heteroleptic organozinc compounds were obtained in THF or 2-MeTHF by direct insertion of zinc dust into the C–Br bond of alkyl bromides. It was found that the presence of a

• primary organozinc reagents. Keywords: alkyl bromides; branched amines; Mannich reaction; multicomponent reaction; zinc; Introduction The multicomponent Mannich reaction is one of the most powerful tools available in organic synthesis for the straightforward generation of α-branched amines [1][2][3

• organolithium reagents, thus limiting functional-group tolerance [11][12][13]. By contrast, heteroleptic (mixed) alkylzinc species (i.e., RZnX) are readily available and can typically be prepared from alkyl halides by direct insertion of metallic zinc into the carbon–halogen bond [14][15][16][17][18][19][20][21

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

• ]-proton shift reaction of various tetrafluoroethylenated imines. Results and Discussion The preparation of substrates used in this study was as outlined in Scheme 3. Namely, the zinc reagent was prepared from commercially available 3,3,4,4-tetrafluoro-1-butene (18) [33] and reacted with various acid

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• (Table 1, entry 6). In contrast, zinc was not effective as an anode material in the carboxylation, probably due to competitive electrochemical reduction of zinc ions generated by electrochemical oxidation of the zinc anode. The deposition of a black precipitate was observed visually at the cathode (Table

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

• ,β-unsaturated imines 9. However, with ethynylimines 12, the enantioselectivity dropped to a modest level. In addition, the reaction with sterically hindered tertiary allylboronates, such as the chiral (R)-α-cyclohexyl-α-methyl-allylboronate required the use of catalytic amounts of zinc tert-butoxide

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• (entry 1) resulted in good conversion to the allylation product, while zinc, magnesium, and graphite (Table 1, entries 3–5) displayed no reaction at all. This observation was somewhat surprising considering that both zinc and tin are very commonly used in conventional allylations in addition to as

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• of IBX ensured the completion of the reaction sequence [96]. A notable advantage of this method is the ability to reuse the catalyst multiple times. In addition to Yb(PFO)3, zinc triflate can also serve as an effective catalyst for the synthesis of pyrazoles 65. It also catalyzes the oxidation of

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• -difluoroethylene was based on 1,2-dichloro-1,2-difluoroethane (HCFC-132) [48][49][50][51][52], prepared from 1,1,2,2-tetrachloro-1,2-difluoroethane (CFC-112) by reduction using lithium aluminum hydride [48][49][50][51] or photoreduction (Scheme 2) [51]. The resulting HCFC-132 reacted with zinc [47][49][52] or

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

• Matteo Gasparetto,
• Balázs Fődi and
• Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

• of ethyl 2-bromoacetate through a pre-activated zinc column (see page 11 in Supporting Information File 1) [44]. The Reformatsky reagent could be obtained in yields varying from 70 to 90% depending on the activation state of the column. The yield of the reaction was determined by titration with

• subsequent re-esterification was necessary to achieve the desired ketoester. Reduction of the oximes Oximes are commonly reduced to the corresponding amines using either palladium on activated carbon and hydrogen gas [65][66][67][68], or with zinc and a Brønsted acid as source of hydrogen [68][69]. Both

• methods were tested and after a brief optimization process, zinc dust and HCl in a mixture of EtOH/dioxane proved to be the best conditions in order to maximize the yield and limit the amino ester instability issues (see Table S6 in Supporting Information File 1). By slightly adjusting the reaction time

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

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• phosphite in the presence of zinc(II) bromide allowed the formation of diethyl [hydroxy(4-hydroxyphenyl)methyl]phosphonate (11) and tetraethyl [(4-hydroxyphenyl)methylene]bis(phosphonate) (13), which were separated by column chromatography (Scheme 3). The synthesis of pure tetraethyl [(4-hydroxyphenyl

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• congestion to the highly reactive 1,3-carbons on the furan ring. Thus, phthaloyl chloride was reacted with mesitylene or 1,3,5-triethylbenzene to produce the corresponding diketones 21 and 22. Each diketone was in turn reacted with zinc metal in glacial acetic acid [9] to afford the corresponding 1,3

• -diarylisobenzofurans 3 and 23. The latter reductions in the presence of zinc likely proceed through the corresponding ketols which are known to undergo ring closure in acidic solution [10][11]. These syntheses utilizing mesitylene or 1,3,5-triethylbenzene are considerably simpler than other approaches that would place

• -filled cuvette. Fluorescence spectra were measured on a FS5 spectrofluorometer (150 W CW Ozone-free xenon arc lamp) from Edinburgh Instruments. 1,3-Dimesitylisobenzofuran (3) To a round bottom flask was added 1,2-phenylenebis(mesitylmethanone) (21, 0.10 g, 0.27 mmol), zinc dust (0.70 g, 11 mmol) and 10

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

• the palladium source in combination with the pyrazinebisoxazoline ligand, (S)-PyraBox (L1), zinc carbonate as base, and methanol as solvent at 40 °C. These initial conditions furnished 2-methoxypyrrolidines arylated at the 4-position, compound 3, as Heck products as illustrated in Scheme 3. The

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• reversibly reopened by the addition of TREN as a competitive ligand. The authors reported a slight luminescence quenching in the zinc-closed state with a decrease in the quantum yield from 0.27 to 0.21. However, Hg2+ presented a special behavior with the formation of a 2:1 complex, the closing of the

• tweezers 16 were then synthetized by Vives and co-workers using a 6,6”-substituted terpyridine this time bearing zinc(II)–salphen complexes [47]. The catalytic activity was evaluated in an acetyl transfer reaction between pyridinemethanol derivatives and anhydrides. For the ortho derivative, a rate

• bonding with the two protonated [9]aneN3 units and two water molecules coordinated to the zinc center. More recently, terpyridine was also used by Crassous and co-workers to create a chiroptic switch (Figure 10) [49]. They synthesized tweezers 18 bearing helicene moieties as functional groups. The two

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• reductant, which can be an organic reductant, such as tetrakis(N,N-dimethylamino)ethylene (TDAE) or Hantzsch ester (HE), or a metal such as zinc (Zn0) or manganese (Mn0). Upon fragmentation, radical species 12 is captured by the oxidative addition complex 125, giving rise to NiIII complex 126. The cross

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• zinc acetate), or 5 mM CdCl2, and in the presence or not of 5 mM GalNAc. Cocrystals of CMA1-Nter in complex with LacNAc (Galβ1-4GlcNAc, Elicityl, #GLY008) were obtained by the addition of 5 mM LacNAc to the protein solution and incubation at room temperature for 30 min prior to crystallization. For

Catalytic multi-step domino and one-pot reactions

• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2024, 20, 254–256, doi:10.3762/bjoc.20.25

• facile stereoselective tandem reaction based on the asymmetric conjugate addition of dialkylzinc reagents to unsaturated acylimidazoles, followed by trapping of the intermediate zinc enolate with carbocations [12]. A practical one-pot synthesis of fluorescent pyrazolo[3,4-b]pyridin-6-ones by reacting 5

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• determined to be 2 and 58 ps, respectively. The observed longer lifetimes attributed to DEA substitution could be due to the larger distance and the Marcus inverted region [143] character, compared with the results obtained for OEF substitution. Guldi et al. synthesized zinc phthalocyanine (ZnPC) covalently

• CS-state formation for 60 depending on the solvent, was also observed for excitation at 458 nm corresponding to the ICT band. A series of multicomponent systems consisting of anilino-substituted TCBD or PCBD coupled with zinc porphyrins (ZnPs) were synthesized, and their photophysical properties were

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• (19) in the presence of activated zinc dust in THF (Scheme 4) [35]. By making minor adjustments to the reaction conditions, such as employing DMF as the solvent and raising the temperature to 100 °C, along with utilizing compound 20 as the starting material, Barton and his team achieved the synthesis

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• appreciable effects. Furthermore, zinc(II) porphyrins 1-Zn and TriCP-Zn bound potassium cations forming dimeric assemblies 2, as demonstrated by the absorption and 1H NMR spectra. Although DCP-Zn and MCP-Zn were also capable of forming dimers, the highest stability and the largest level of attraction between

• macrocyclic entities attached to pyrrolic subunits, acted as a receptor for alkali and alkali earth metal cations. Incorporating zinc(II) and nickel(II) into the porphyrin cavity yielded 8-Zn and 8-Ni. Langford and co-workers developed an efficient method for synthesizing a series of porphyrin-appended crown

• sodium(I), zinc(II), magnesium(II), and barium(II) [106][107][108][109]. Association constants of the reported host–guest complexes showed similar values to those of diazacrown ethers [110][111]. Johnston and Gunter presented a crown ether-capped porphyrin receptor 10, which showed unexpected binding