Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• maleamides (Z)-3 in the solid state (Figure 3a), leading to an enhancement in the porosity of the metal-organic crystalline material. Noteworthy, a MOF having (Z)-3 as the only ligand was also prepared, showing a faster rotational dynamics of the threads within the crystalline array compared to that of

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• disorders) [16] (Figure 2). 10,11-Dihydrodibenzo[b,f]azepine-based ligand 7 and a methyl analogue thereof are known to form pincer complexes with Pd, Ir, Rh and Ln [5], whereas a copper(II) wagon wheel complex of 8 was reported in a molecular organic framework (MOF) (Figure 3) [6]. 4,4'-(5-(Pyridin-2-yl

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• rings, and is important to ensure stability in the potential MOF structures derived from the proposed linkers. The geometry of these linkers, termed as V-shaped, was selected to try and move away from the pillared-layered structures that are obtained when using linear diphosphonate linkers, which are

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• , three-component procedure was also explored for the preparation of 3-aryl-4H-benzo-1,4-thiazin-2-amines [18]. 3-Aryl- and 3-alkyl-4H-benzo[b][1,4]thiazine-4-carbonitriles 2 (Figure 1) were synthesized in high yield from the corresponding 2-aminobenzothiazoles using the copper–organic framework Cu–MOF-74

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• charge–transfer transitions [95]. These transitions are commonly observed in metal–organic framework (MOF) HPCats, discussed more in Section 2.5. Dye-sensitised semiconductor photocatalysts have organic photosensitiser molecules immobilised to their surface. This strategy is typically used to activate a

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• metal-organic (MOF) and covalent-organic frameworks (COF), have significantly expanded the use of these compounds in photoredox catalysis due to the singular electronic features of these materials and chemical robustness as catalysts. The appearance of porphyrins as photoredox catalysts for C–C bond

• hydroxylation of arylboronic acids by a reductive quenching using a MOF Sn(IV) porphyrin-containing photocatalyst (UNLPF-12) under visible light irradiation. The authors obtained a variety of phenolic products in 83–96% yields (Scheme 15) [40]. The key steps of the mechanism are both the generation of

• superoxide radical anion by a reductive quenching and the rearrangement of the hydroperoxide intermediate [41]. The heterogeneous protocol using MOF porphyrins was significantly faster than the corresponding homogeneous photocatalysis, which was attributed to higher photostability of the porphyrins as MOF

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• intermolecular oxidative diamination of haloalkynes, mild reaction conditions and efficient conversion of the alkyl-substituted haloalkynes to the halogenated product were great improvements over existing methods. Stimulated by the work of Luz et al. [98] and Phan et al. [99] with Cu(BDC)MOF (BDC: 1,4

• -benzenedicarboxylate), Puthiaraj and co-workers have unprecedently discovered the catalytic activity of this metal-organic framework (MOF) for the synthesis of imidazo[1,2-a]pyridines [100]. The three-component, one-pot reaction between 1, 3 and nitromethane (10, Scheme 5) involved an intermolecular aza-Michael

• addition with a subsequent intramolecular cyclization catalyzed by Cu(BDC)MOF. Further, the LC–MS study of the reaction mixture has shown the imine formation to be the major pathway rather than β-nitrostyrene. The reaction involved a two-step reaction mechanism in which aza-Michael adduct 13 was formed in

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• of the dipolar rotors must be compatible with MOF growth. Preconditions 1. and 2. are somewhat contradicting each other. In the most simple treatment, the dipole moment is proportional to the point charges times their distance. However, in a real chemical situation the distance between the charges

• cannot be arbitrarily increased because with increasing lattice parameters controlled MOF growth becomes increasingly difficult (e.g., interpenetration). Moreover, large cavities in solids are usually difficult to keep free from solvents or other impurities that would hamper free rotation. Hence, a

• in a MOF. Five different orientations in C2v, C2h and D2h symmetry are considered. The energy difference between the most favourable and the most unfavourable orientation is 9.7 kcal mol−1. It is important to note that the energy states of 3D ensembles of dipoles assuming periodic boundary conditions

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• crystalline materials constructed from metal connecting nodes and molecular building blocks [62][63][64]. To explore the utilities of the microenvironments provided by MOFs for B12 catalytic reactions, a new MOF {Zn4Ru2(bpdc)4·4NH2(CH3)2·9DMF}n (H2bpdc = 4,4′-biphenyldicarboxylic acid) was prepared by the

• reaction of H2bpdc, Ru(bpy)2Cl2, and a zinc source under solvothermal conditions (bpy = 2,2′-bipyridine, Scheme 5) [41]. The molecular photosensitizer [Ru(bpy)3]2+ was incorporated into the MOF through adsorption to form Ru@MOF, accompanied by a color change. Furthermore, 1 was effectively immobilized on

• Ru@MOF, as was confirmed through ESR measurements. The resultant heterogeneous hybrid catalyst B12-Ru@MOF successfully mediated the photochemical carbon-skeleton arrangement. Previous studies had demonstrated that the hemolytic cleavage of the Co(III)–C bond of the alkylated complex of 1 generated Co

Determining the predominant tautomeric structure of iodine-based group-transfer reagents by ¹⁷O NMR spectroscopy

• Nico Santschi,
• Cody Ross Pitts,
• Benson J. Jelier and
• René Verel

Beilstein J. Org. Chem. 2018, 14, 2289–2294, doi:10.3762/bjoc.14.203

• corroboration came about by successfully encapsulating 5b, an oil under ambient conditions, in a metal-organic framework (5b@MOF). This non-trivial protocol rendered it amenable to X-ray diffraction studies confirming the aforementioned structural reassignment. From a theoretical standpoint, acyclic isomer 5b

• would have been feasible without having to resort to the preparation of crystalline congeners and/or the preparation of 5b@MOF. Importantly, establishing a reliable way to differentiate cyclic (a) from acyclic (b) isomers in solution would facilitate future structure determination of similar iodine

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• this single compound. 6.2. Switchable catenanes in ordered arrays Besides ordered arrays on surfaces, on nanoparticles or in Langmuir–Blodgett films, a possibility to arrange bistable catenanes in an ordered fashion is to incorporate them into the rigid scaffold of a metal-organic framework (MOF) [107

• ]. An advantage of this strategy is that the relatively labile organic switches are protected from degradation in this solid material. In 2016, the groups of Hupp, Farha, and Stoddart reported on a bistable donor–acceptor catenane 28 which is inserted in the Zr-based MOF NU-1000 (Figure 26) [108]. The

• MOF NU-1000 consists of Zr6 nodes which are bridged by 1,3,6,8-tetrakis(p-carboxyphenyl)pyrene ligands [109]. Four hydroxy groups of each metal cluster are pointing into the mesoporous channels of the MOF and can be post-functionalized. Similar to a previous report about rotaxanes implemented into a

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• comportment of G-1 piperazine dendron D-N

  NH being not entirely ruled out [68]. In line with this hypothesis, we recently described [35] the aptitude of the non-O-n-octylated analogue of G-2 dendrimer 4 (Scheme 3) to deprotonate Hemin completely (1:5 molar ratio), thus generating a new MOF for H2O2

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• enhancement of MOF structural and stability properties [90][91]. Bioactive molecules like caffeine [92][93] and anticancer drugs [94][95][96][97][98] were incorporated in ZIF-8 and tests proved that these systems allowed for a controlled drug release. Further studies involving ZIF-8 with encapsulated

• (encapsulated) as a guest within the pores of the MOF. In the second situation, the choice of the linker is crucial, as it needs to be an organic molecule listed of the generally regarded as safe (GRAS) compounds, an endogenous compound or a bioactive molecule. In both classes, the judicious choice of the

• mechanochemical approach called “SMART” (secondary basic units-based mechanochemical approach for precursor transformation), in which pre-assembled secondary building units were explored. This method led to the successful synthesis of MOF-5 by mechanochemistry starting from Zn4O and 1,4-benzenodicarboxylic acid

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• identified as metal organic framework (MOF) or coordination polymers that are synthesized by reaction with a metallic salts (e.g., copper [65], lanthanides [66]) under hydrothermal conditions [67][68] or by insertion of phosphonic acid in low dimensional inorganic materials like layered double hydroxide (LDH

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• mechanochemical synthesis of a MOF from ZnO and imidazole in the presence of a small amount of N,N-dimethylformamide [41]. This study revealed reaction kinetics consistent with a 2nd order reaction rate law, rationalized through a “pseudo-fluid” reaction model in which the rate-determining factor is the frequency

Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction

• Qi An,
• Youssef Hassan,
• Xiaotong Yan,
• Peter Krolla-Sidenstein,
• Tawheed Mohammed,
• Mathias Lang,
• Stefan Bräse and
• Manuel Tsotsalas

Beilstein J. Org. Chem. 2017, 13, 558–563, doi:10.3762/bjoc.13.54

• reaction (TYC); Introduction The synthesis of microporous organic and inorganic materials such as zeolites [1], mesoporous silica [2] as well as metal-organic frameworks (MOF) [3][4] and covalent organic frameworks (COF) [5][6][7] attracted large attention because of their high potential in catalysis, gas

Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

• Arne Klinkebiel,
• Ole Beyer,
• Barbara Malawko and
• Ulrich Lüning

Beilstein J. Org. Chem. 2016, 12, 2267–2273, doi:10.3762/bjoc.12.219

• the methoxy group gave the respective amino and hydroxy-substituted triazine linkers. Keywords: isoreticular; linker; MOF; Suzuki coupling; triazine; Introduction A typical building block for many metal–organic frameworks (MOFs) [1][2][3][4] carries two functional groups such as carboxylic acids or

• -benzenetricarboxylic acid. By elongating the „arms“ of the linkers, larger pores can be achieved, and often the MOF structures containing extended linkers resemble those obtained with the smaller parent linker (isoreticular structures, see for instance [5]). In the case of the tritopic linker 1,3,5

• -benzenetricarboxylic acid (BTC, forming HKUST-1 [6] in the presence of copper ions), an obvious elongated building block is BTB (1,3,5-benzenetribenzoate, Figure 1, left) forming for instance MOF-14 [7]. But this type of elongation has a drawback: the direct vicinity of the aryl groups does not allow planarity due to

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13