Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• applications in organic chemistry. Keywords: asymmetric synthesis; catalyst recycling; heterogenisation; organocatalysis; solid support; Introduction Organocatalysts are small molecules that do not contain a metal atom in the reaction centre and are able to increase the speed of reactions. They have proven

• performance is crucial to the development of high performance immobilised organocatalysts. Review Characteristics of the solid support Considering the support type, organic polymer-supported, silica-supported [20][21][22][23][24][25], glass beads [26] and magnetic nanoparticle-supported [27][28][29][30][31

• 39% ee for a pore size of 11.3 nm [64]. Catalyst supports must meet certain criteria, including being chemically inert, and the supported catalyst should exhibit high stability across various reaction conditions while also being easily recyclable [8][64]. When the solid support is not inert, it can

Synthesis of substituted triazole–pyrazole hybrids using triazenylpyrazole precursors

• Simone Gräßle,
• Laura Holzhauer,
• Nicolai Wippert,
• Olaf Fuhr,
• Martin Nieger,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2024, 20, 1396–1404, doi:10.3762/bjoc.20.121

• . It offers the additional benefits of chemistry on solid support: straightforward purification of the resin-bound intermediates by washing steps and a high throughput that allows for faster derivatization. Further research is necessary to establish a protocol for the cleavage of 4-substituted

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• of alkenes with in situ-generated HCl on a solid support. They found that K10 montmorillonite gave good results for the hydrochlorination of 1-methylcyclohexene (78) with SOCl2 as the HCl source (Scheme 13). Surprisingly, they not only obtained the expected product 50 but also the regioisomer 79

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

• is an intriguing solid support, since it is a low cost, commercially available and non-hazardous support, that can be employed in tandem with various traditional catalysts [70]. Some examples in literature are ZrOCl2·8H2O/SiO2 [71], P2O5/SiO2 [72], LiHSO4/SiO2 [73], (PhCH2PPh3)+Br−/SiO2 [74], H2SO4

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• achieved, for example, by immobilizing the catalysts to a solid support [15], e.g., silica gel [16][17][18], organic polymers [19][20][21], magnetic nanoparticles [22][23], or by membrane separation, e.g., using organic solvent nanofiltration (OSN) [24][25][26], which methods can be easily implemented in

Linker, loading, and reaction scale influence automated glycan assembly

• Marlene C. S. Dal Colle,
• Manuel G. Ricardo,
• Nives Hribernik,
• José Danglad-Flores,
• Peter H. Seeberger and
• Martina Delbianco

Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77

• Universität Berlin, Arnimallee 22, 14195 Berlin, Germany 10.3762/bjoc.19.77 Abstract Automated glycan assembly (AGA) affords collections of well-defined glycans in a short amount of time. We systematically analyzed how parameters connected to the solid support affect the AGA outcome for three different

• glycan sequences. We showed that, while loading and reaction scale did not significantly influence the AGA outcome, the chemical nature of the linker dramatically altered the isolated yields. We identified that the major determinants of AGA yields are cleavage from the solid support and post-AGA

• (BBs) [1][2]. Iterative cycles of glycosylation, capping, and selective deprotection afford the support-bound glycan with a programmable sequence (Figure 1A). The protected glycan is then cleaved from the solid support and subjected to post-AGA deprotection steps to reveal the target glycan. AGA is

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• duplicative functionalization of the backbone. Moreover, commercially available CPAs are extremely expensive (>> 500,000 $/mol) and immobilizing the CPAs on a solid support is not straightforward [19][20]. In order to avoid this, a significant investment in time must be made to complete the multistep

• straightforward and accomplished late-stage, to avoid carrying the chirality through multiple steps and the possible erosion of enantiomeric excesses. Preferably, both enantiomers of the CPA should also be available and immobilization of the CPA on a solid support should be possible. In this paper, we report our

• cross-coupling, and 2) immobilization on a solid support via reduction and reaction of the aniline with an electrophile such as polystyrene isocyanate. DOPO scaffold We previously reported the syntheses of both enantiomers of 8-phenyl DOPO 3 [38]. The syntheses proceed in only three steps (including the

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• a solid support following a linear approach (Figure 1D). Cycles of glycosylation and selective deprotection are iteratively performed to access the desired polysaccharide with full control over the length and the monosaccharide sequence [32]. Upon completion of the assembly, the desired product is

• released from the solid support and subjected to global deprotection. Similar to chemical polymerization, the removal of the PGs is a significant bottleneck. Additionally, several transformations remain challenging due to the poor reactivity or limited stereocontrol of certain BBs [33][34][35][36][37]. To

• NMR studies on a collection of 13C-labelled hexamers [157]. Similar issues during deprotections were not observed when the β(1–6) backbone was substituted with β(1–3) branches [158][159][160][161][162][163][164][165][166] and long oligomers could be synthesized on solid support [157][166] or in

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• latter strategy can be divided into the conjugation of amine groups onto ONs still attached to the solid support, or onto ONs in solution after cleavage from the solid support. The C-5 position of the pyrimidine ring has in general been the most used attachment point since it is not involved in hydrogen

• simultaneously with cleavage from the solid support [66]. It was found that the modified ON gave an improved duplex stability relative to the unmodified ON by 15 °C at 150 mM NaCl [66]. Later, improved syntheses of the phosphoramidite derivatives of guanine analogues have been developed [67]. Thus, many studies

• solid support or incorporated using conventional phosphoramidite chemistry. Previously such a method had been used to attaching different moieties onto an ON still bound to a solid support [89][90]. Putrescine (47), spermidine (48), spermine (49) and a synthetic pentaamine (50) were attached to the 2

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• phosphoramidites 160 and 164 which were then incorporated into oligodeoxynucleotides using automated solid phase synthesis. The synthesized oligonucleotides were removed from the solid support by treatment with concentrated aqueous ammonia which resulted in the formation of incorporated monomers 161 and 165 by

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

• drawbacks currently account for a large proportion of the research being conducted within the flow chemistry community. The continuous processing of slurries, for example, is now routinely performed [44][45][46][47][48], also, the use of scavengers (e.g., solid support reagents) [49][50][51] and devices

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• dipalmitoyl-Dap-T7 and dipalmitoyl-Dap-Tat (Figure 1A). Double lipidation ensures a more stable lipid-membrane-anchoring compared to a single fatty acid chain or cholesteryl variant [27][28][29]. The careful choice of Dap and palmitic acid allows for the entire synthesis to be performed on solid support with

• -HAIYPRH-NH2 Tat: H-YGRKKRRQRRR-NH2 Modified Tat: dipalmitoyl-Dap-YGRKKRRQRRR-NH2 Peptide conjugation with a lipid reagent The peptides were N-terminally modified on solid support by coupling of Fmoc-Dap(Fmoc)-OH, followed by the coupling of palmitic acid to afford the complete peptide–lipid conjugates

• . Coupling of Fmoc-Dap(Fmoc)-OH and Fmoc deprotection were carried out as described above. To ensure the complete lipidation of the two free amines of Dap, 8 equiv of palmitic acid, 8 equiv of HATU, and 12 equiv of DIPEA in DMF were used. Cleavage of the peptide–lipid conjugates from the solid support and

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• traditional methods [62][63]. The catalyst offered recovery and reusability up to five successive runs with excellent yields (86% to 95%). The approach paved a new way to solid-support-mediated MWA-MCR using a heterocatalyst (Scheme 22). A possible mechanism suggested by authors proceeded via a Michael

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• yield was also improved by minimising the handling of the solid support and performing the reaction using a microtube pump to deliver the sulfonyl azide solution onto the column with CPG support. The cleaved and deprotected N+- and Ts-ONs were initially purified using reversed-phase (RP) HPLC. However

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases

• Naohiro Horie,
• Takao Yamaguchi,
• Shinji Kumagai and
• Satoshi Obika

Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54

• Support™ T 40s (GE Healthcare) was used as a solid support. The amidite solution was dehydrated. The standard synthesis cycle was used for the assembly of the reagents except that the coupling time was extended to 16 min. The synthesis was carried out in the trityl-on mode. The oligonucleotides were

• treated with a 1:1 mixture of 7 N ammonia solution in methanol and 40% aq. methylamine at room temperature for 10 h to remove the solid support, and then the mixture was heated at 60 °C for 10 h (mC) or 15 h (A and G). After deprotection, the oligonucleotides were rapidly purified using a Sep-Pac® Plus

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• compared to 2D materials, thanks to a typical 8–16 nm outer diameter tubular morphology [215][216] and the potential for facile metal doping via ion-exchange of the solid support [217][218]. Lewis acid-type catalytic activity was also postulated for γ-Fe2O3 NPs, which provided BHET in 90% yield at 300 °C

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• organic reactions in our previous work. In 2014 [14], LS were used by our group, for the first time, as a solid support of cationic catalysts. The obtained catalysts were then successfully applied to many organic transformations, in which the catalysts showed not only high activity but also good

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• peptide from the solid support, and iv) purification of the peptide by reversed-phase HPLC. Fmoc-protected Rink amide resin (0.45 g, 0.5 mmol) was swelled in 10 mL of DMF for two hours. After that, the swelled resin was loaded into the special apparatus [23], and the solvent was drained off. The swelled

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

• heterogeneous photocatalysis is immobilising a molecular photocatalyst to a solid support. Most materials have inherent surface functionalities or can be modified to act as supports through covalent or electrostatic interactions, presenting a plethora of strategies to immobilise any photocatalyst with a

• chemistry as previously discussed. This combines the ease of separation and recyclability of a heterogeneous catalyst, with the detailed characterisation, accessibility and synthetic versatility of a homogeneous photocatalyst. Some desirable properties of a solid support are hence; (i) a strong

• organic ligands (struts) that connect the nodes, and (iii) as a solid support for other HPCat materials immobilised in the void spaces of the porous material [1][176][177][178][179][180]. Each material has its own subtle differences but generally adheres to the fundamental principles discussed in Sections

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• -aminopropyl)triethoxysilane (APTES)/KIT-5 (CuI/AK, 68) using CuI as the copper source [33]. The APTES/KIT-5, as a solid support, was added to a vessel containing CuI in acetonitrile. After stirring under reflux and a nitrogen atmosphere for 5 h, the solid product 68 was collected by filtration. The solid was

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• linker as solid support [25]. A typical AGA cycle consisted of three modules. The acidic wash module prepared the resin for glycosylation by quenching any remaining base from a previous cycle. In the glycosylation module, the thioglycoside donor was coupled to the resin upon activation with NIS and TfOH

• protecting groups, whereby Fmoc was cleaved by piperidine (20 vol % in DMF), while Lev was removed using hydrazine acetate. Iterative cycles continued until the desired structure was obtained. The oligosaccharide products were cleaved from the solid support using a flow UV photoreactor, followed by a two

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• after the cleavage from the solid support. Among the initial studied photoswitchable PNAs, the PNA12(oF4Azo) (3) displayed the most promising properties as reversible modulator of oligonucleotide hybridization. Thus, it displayed the fastest reversible isomerization (≈2 s for cis → trans and ≈120 s for

Synthesis and conformational preferences of short analogues of antifreeze glycopeptides (AFGP)

• Małgorzata Urbańczyk,
• Michał Jewgiński,
• Joanna Krzciuk-Gula,
• Jerzy Góra,
• Rafał Latajka and
• Norbert Sewald

Beilstein J. Org. Chem. 2019, 15, 1581–1591, doi:10.3762/bjoc.15.162

• with the aim of excluding pH-dependent charge effects and to simulate a protein environment. The introduction of a methyl amide function at the C-terminus of glycopeptides was carried out on solid phase. The N-methylation of the peptide terminus on solid support was an efficient four-step procedure

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• removed with an acid in each synthetic cycle. The exo-amino groups of nucleosides dA, dC and dG are protected with acyl groups, the nascent ODN is anchored to a solid support via a base- or nucleophile-cleavable linker, and in the most widely used phosphoramidite technology the phosphate groups are

• MerMade 6 DNA/RNA synthesizer. The dT-Dmoc-CPG (4) was used as the solid support. Detritylation was carried out under standard conditions suggested by the synthesizer manufacturer for 1 µmol synthesis. The 0.1 M acetonitrile solutions of phosphoramidite monomers 3a–c and the commercially available 5'-DMTr

• temperature briefly. This removed the β-cyanoethyl phosphate protecting groups to give 32. HPLC analysis of the DBU solution did not found any ODN that was cleaved prematurely – an observation consistent with the slow rate of cleavage of succinyl-anchored ODNs from solid support under similar conditions [50