Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• electrophile [175]. In terms of polarization, since cages are invariably charged [36], a few MOCs have demonstrated charge stabilization of transition states (Figure 5B). A key example uses the highly successful Raymond gallium-based cages, exploited by Raymond, Bergman and Toste [21][37][107][155][165][168

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• cell membrane integrity [21]. In the context of cancer therapy development, metal complexes of N-acylhydrazones stand out. For example, Firmino et al. demonstrated that gallium(III) complexes of isoniazid-derived hydrazones exhibit strong cytotoxicity against HL-60 and HCT-116 cancer cell lines [22

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• ][32][33][34][35][36][37][38][39], gallium [36][40][41][42][43][44], and indium [36][45] reagents being used for the preparation of group 13 reagents. Group 13 exchange has recently been used to enable catalytic turnover in traditionally stoichiometric reactions, expanding the use of group 13 compounds

• reduction of CO2 with Me2S·BH3 as the terminal reductant [101]. Gallium catalysis Pioneering studies by Woodward reported the enantioselective reduction of ketones using HBcat and a mixture of MTBH2/LiGaH4 as the catalyst, achieving high yields (up to 96%) and enantioselectivities (up to 93% ee) (Scheme 24a

• ) [111]. The reaction was proposed to proceed through the enantioselective reduction of the ketone 95 by gallium hydride 96, followed by Ga‒O/B‒H exchange with HBcat to give an enantioenriched alkoxy catechol borane 98, affording the alcohol after workup (Scheme 24a). The mechanism was later explored in

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• gallium-catalyzed synthesis of unsymmetrical CF3-substituted 3,3’- and 3,6’-bis(indolyl)methanes from trifluoromethylated 3-indolylmethanols [71]. Alcohol 61 reacts with indole 62 to provide a product 63 or 64, depending on the temperature (Scheme 17). The authors suggested that an indolium ion 65 is

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• -tri(tert-butyl)phenolate], for example, a Cs…CH3 contact of 3.596(5) Å contributes to its form as a 1D coordination polymer [33]. In the caesium salt of the gallium metallate [Cs(toluene)2{CN(GaMe3)2}], multiple Cs…CH3 interactions in the range from 3.54–3.64 Å help generate its three-dimensional

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• treated with the corresponding metal phosphate, which can be prepared in situ following our previously described procedure (Scheme 2b,c) [37][38]. UV analysis indicated that the indium salt 1a or gallium salt 1b (0.05 mM) could induce ca. 92% dissociation of trityl bromide (0.05 mM) to generate the trityl

Repurposing the anticancer drug cisplatin with the aim of developing novel Pseudomonas aeruginosa infection control agents

• Mingjun Yuan,
• Song Lin Chua,
• Yang Liu,
• Daniela I. Drautz-Moses,
• Joey Kuok Hoong Yam,
• Thet Tun Aung,
• Roger W. Beuerman,
• May Margarette Santillan Salido,
• Stephan C. Schuster,
• Choon-Hong Tan,
• Michael Givskov,
• Liang Yang and
• Thomas E. Nielsen

Beilstein J. Org. Chem. 2018, 14, 3059–3069, doi:10.3762/bjoc.14.284

• distinct from other conventional antibiotics, which may offer alternative therapeutic approaches towards persistent infections. In recent years, metal-containing compounds have been identified as antimicrobial agents. Gallium was shown to disrupt the iron metabolism of P. aeruginosa and efficiently kill

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• weakness it required long reaction times (5 days). In 1997, Shibasaki and colleagues reported a gallium-lithium bis(binaphthoxide) complex 43, easily prepared from GaCl3, (R)-binaphthol and butyllithium in THF, as a catalyst for the asymmetric opening of symmetrical epoxides in the presence of 4 Å

• ranged from 67–92%, with enantioselectivities of 21–73% [41]. In 2009, Sun et al. reported heterobimetallic gallium–titanium variations of the same salen complexes as excellent catalysts for the thiolysis and selenolysis of meso-epoxides, giving the desired β-hydroxy sulfides and selenides in near

• oxidation to β-hydroxy sulfoxides under microwave irradiation. Gallium triflate-catalyzed ring opening of epoxides and one-pot oxidation. Thiolysis of epoxides and one-pot oxidation to β-hydroxy sulfoxides using Ga(OTf)3 as a catalyst. Ring opening of epoxide using ionic liquids under solvent-free

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• brain. AuNPs were decorated in a controlled ratio with glucose, neuropeptides and a chelator of gallium-68, a sensitive positron emission tomography (PET) tracer, affording the quantification of BBB permeability in healthy small animals. Glyco-gold nanoparticles in immunology The development of

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• gallium at 0 °C and Sn(IV) at 25 °C a diastereomer of 5a also formed in 20 and 29% yields, respectively. Generally, with nearly all metals, the yield of 5a increased dramatically when the temperature was raised to 25 °C, but dropped at higher temperatures. The decreased yield at 67 °C may emerge from the

• . The larger the amount of aldehyde in the reaction, the higher is the yield of monoaldol product 6a, which supports a thermodynamically controlled equilibrium as further confirmed by the following observations: (1) with gallium(III) two diastereomeric tetrahydro-2H-pyran-2,4-diols are formed at 0 °C

• of the yields with increasing flow rates is easily explained with the short reaction time. Discussion The experimental results indicated that two diastereomeric tetrahydro-2H-pyran-2,4-diols were formed at 0 °C in the presence of gallium and at 25 °C with Sn(IV), but only one (i.e., 5a) at elevated

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• ]. Gallium-68. NOTA [22] and DOTA [23] have been reported to form a stable complex with gallium(III) and those two ligands are widely used in the preparation of 68Ga-based PET probes. Advantageously, Ga complexes of porphyrins and corroles are known to be very stable allowing possible PET imaging

• trifluoroacetic acid, followed by oxidation under the action of DDQ. Cu and Ga complexes were prepared by the strategy outlined in Scheme 2. The insertion of Cu into corrole 1 was easily achieved with Cu(OAc)2·H2O in THF during 15 min. To obtain the gallium corrole 8b, free-base azidocorrole 1 was dissolved in a

• solution of GaCl3 in pyridine and then refluxed for 1.5 h as previously described [28]. Corroles 8a and 8b were prepared and characterized by 1H NMR, HRMS and UV–vis absorption spectroscopy. Different metal ions were introduced inside the porphyrin core 2, namely copper, gallium, indium and manganese. For

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

• Rajesh Munirathinam,
• Roberto Ricciardi,
• Richard J. M. Egberink,
• Jurriaan Huskens,
• Michael Holtkamp,
• Herbert Wormeester,
• Uwe Karst and
• Willem Verboom

Beilstein J. Org. Chem. 2013, 9, 1698–1704, doi:10.3762/bjoc.9.194

• Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and

• X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydration of oximes, using cinnamaldehyde oxime as a

• model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3. Keywords: dehydration of oximes; flow chemistry; gallium; microreactors; Lewis acid catalysis

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• combination of Cu(OTf)2/TMSA (TMSA = trifluoromethanesulfonic acid) [30]. The same reaction was also successfully carried out by Li and co-workers using FeCl3 as catalyst in a homogeneous medium [31]. Further Yadav et al. demonstrated an elegant hydroarylation of different phenols in the presence of gallium

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• bidentate ligands for metals such as iron or gallium that require an octahedral geometry. Katoh coupled N-hydroxypyrazinone substituents to cone-14a in order to prepare 23 (Scheme 13). Binding Ga3+ with remote lower-rim groups induced the cooperative binding of alkyl ammonium cations by the macrocycle [38

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• large polyarenes 2 and more simple 3-arylfluoranthenes by using gold(I)- or gallium(III)-catalyzed hydroarylation reactions. Results and Discussion First, we examined the cyclization of 3 to give 4 or 4' [22][24][26] (Table 1) with cationic gold(I) catalysts 5 [56] and 6 [57] (Figure 1), which have been

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• , gallium and indium trichlorides with phenyl azides containing a variety of substituents. Analysis of the spectra showed that 4-methoxy-, 3-methoxy- and 2-methoxyphenyl azides all gave ‘dimer’ radical cations [ArNHC6H4NH2]+• and trimers [ArNHC6H4NHC6H4NH2]+• followed by polymers. 4-Azidobenzonitrile, with

• suggested that the unpaired electrons were accommodated in extensive π-delocalised orbitals. A mechanism to account for the reductive conversion of aromatic azides to the corresponding anilines and thence to the dimers and trimers is proposed. Keywords: aluminium; aromatic azides; ENDOR; EPR; gallium

• ; indium; Introduction The number of applications of indium [1][2][3][4][5][6], gallium [7][8][9][10][11] and other group 13 metal derivatives, as promoters of radical reactions, has been increasing ever since the original work of Baba and co-workers with dichloroindium hydride [12][13][14][15][16

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III) ions

• Markus Albrecht,
• Olga Osetska,
• Thomas Abel,
• Gebhard Haberhauer and
• Eva Ziegler

Beilstein J. Org. Chem. 2009, 5, No. 78, doi:10.3762/bjoc.5.78

• ligand leading to a significant change of the observed CD spectra. Small trivalent metal ions like aluminium(III), gallium(III) or iron(III) which are able to form (distorted) octahedral coordination compounds lead to UV–vis spectra which show isosbestic behaviour. However, the titration curves show more

Functional properties of metallomesogens modulated by molecular and supramolecular exotic arrangements

• Alessandra Crispini,
• Mauro Ghedini and
• Daniela Pucci

Beilstein J. Org. Chem. 2009, 5, No. 54, doi:10.3762/bjoc.5.54

• increase absorption in the visible region, have given excellent results and further experiments are still in progress. Gallium (III) Since the nature of the metal centre represents an important tool for tailoring specific molecular shapes and topologies, we have selected the Ga(III) ion, never used before

• intermolecular interactions in the crystalline organization grafted around the gallium(III) centre [61]. In this way a unconventional jellyfish shape molecule has been obtained and its molecular structure has been confirmed through single crystal X-ray diffraction (Figure 6). Despite its unusual molecular shape

• -diketonates. Molecular structure of Pt(II) complexes based on 4,4′-disubstituted 2,2′-bipyridines. Molecular structure of Zn(II) complexes based on polycatenar 4,4′-disubstituted 2,2′-bipyridines. Molecular structure of a gallium(III) mesogen. Acknowledgments Financial support received from the Ministero