Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• , along with electrostatic and hydrogen-bonding interactions. This behavior not only allowed for the selective activation and deactivation of organocatalytic activity but also facilitated efficient catalyst recovery at the end of the catalytic reaction. Notably, control experiments supported the

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

• , acetonitrile, with 91–100% efficiency, and the catalyst was reused in five reaction cycles without the loss of activity and selectivity. Keywords: baclofen; catalyst recovery; lipophilic cinchona squaramide; organocatalysis; stereoselective catalysis; Introduction In today’s chemical industry, catalytic

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

• the catalyst expense. As enantioselective catalysts require expensive structural modifications, the possibility of immobilisation would facilitate catalyst recovery/recycle and drastically reduce the cost of the associated process. In 2012, silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 was used to

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• catalysis are well-known and documented [1][2][3]. However, problems associated with catalyst recovery limit the application of homogeneous catalysts in industry and sometimes make their heterogenization necessary. Unfortunately, the immobilization of a homogeneous catalyst onto supports, such as

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

• of product separation, catalyst recovery, simplifying the production process, and cleaner operation conditions [18][19][20]. Thus far, several heterogeneous catalysts have been explored for CuAAC and RuAAC processes. The catalytic activities of heterogeneous copper catalysts as novel catalysts are

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• systems include: 1) the site isolation of reactive components (enabling cascade reactions), 2) the ability to convert hydrophobic substrates in water (under green conditions), and 3) the facile catalyst recovery. All these attractive features are covered in this review. Moreover, in this review we have

• stabilized by colloidal particles that adsorb at the water–oil interface. They are more stable than classical emulsions and do not require the usage of small molecule surfactants. This is a big advantage in downstream processing and product and catalyst recovery. The enzyme Candida antarctica lipase B (CalB

• used to carry out asymmetric Mukaiyama aldol reactions. Although this system did not result in any substantial improvements in yields or enantioselectivities, it allowed for facile catalyst recovery and recycling. Dendrimers were also used to encapsulate bimetallic catalysts to attain highly selective

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

• Krzysztof Skowerski,
• Jacek Białecki,
• Stefan J. Czarnocki,
• Karolina Żukowska and
• Karol Grela

Beilstein J. Org. Chem. 2016, 12, 5–15, doi:10.3762/bjoc.12.2

• (Figure 1) [5]. However, heterogenisation of these complexes was also extensively tested, as their applications in a solid form can be beneficial [6]. The efficient removal of ruthenium from metathesis products, possibility of catalyst recovery and reuse as well as their potential use in continuous

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• carefully cast and well-characterized [25][26]. As we used commercially available PTFE tape for which tolerances are considerably higher, drawing general reproducible conclusions may be more difficult. PTFE has found use as both a catalyst carrier and a means of catalyst recovery by Gladysz [28] and as a

• support when taking IR spectra [29]. The most common everyday laboratory use of PTFE is as a protective coating of magnetic stirring bars. Bulk PTFE is chemically identical to PTFE tape. However, Dihn and Gladysz reported that it behaves very differently in reactions involving fluorous catalyst recovery

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• ][55][56][57][58][59][60][61]. Due to the nature of the reaction and ready availability of catalyst, these asymmetric reactions could be undertaken at the mole-scale (giving more than 100 g of product), with possibility of both catalyst recovery and reuse. The scalability of these reactions is first

• (Scheme 11) [62]. The O-diphenylacetoyl derivative was prepared using an analogous O-acylation procedure by Gruttadauria and co-workers in 2010 (Scheme 11) [63]. These compounds proved very efficient as organocatalysts in asymmetric aldol reactions in aqueous media. Even catalyst recovery and reuse (up to

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• of the reaction [11][12][13]. In addition, the easy handling (not involving the use of a complex chemical apparatus), possibility of catalyst recovery, mild experimental (room temperature, atmospheric pressure, etc.) and non-hazardous environmental conditions as well as organic solvent-, moisture

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• arenediazonium salt surrogates in the Suzuki–Miyaura cross-coupling reaction [29]. Pd2(dba)3 and P(tBu)3 were used as catalyst in this reaction where, as in most of homogeneous catalytic systems, the difficulties of catalyst recovery and recycling constitute major problems. One possible solution to these

From discovery to production: Scale- out of continuous flow meso reactors

• Peter Styring and
• Ana I. R. Parracho

Beilstein J. Org. Chem. 2009, 5, No. 29, doi:10.3762/bjoc.5.29

• reaction. This makes catalyst recovery and re-cycling problematic if not impossible. It also leads to the possibility of metal contamination at trace levels in the final product. Furthermore, added phosphines and other activating agents tend to be expensive and also difficult to recover, adding both an

• applications. In an ideal case [16] the catalyst can be recovered and reused several times before it eventually deactivates. At the same time, catalyst recovery can also reduce the environmental pollution caused by heavy metals used in the catalyst systems. When using a supported metal catalyst, another

EcoScale, a semi- quantitative tool to select an organic preparation based on economical and ecological parameters

• Koen Van Aken,
• Lucjan Strekowski and
• Luc Patiny

Beilstein J. Org. Chem. 2006, 2, No. 3, doi:10.1186/1860-5397-2-3

• factor accounting for reaction and postreaction solvent and/or catalyst recovery) a general algorithm for reaction mass efficiency has been proposed. [20] This has been followed by the introduction of minimum atom economy (AE)min and maximum environmental impact factor Emax that have been applied to over