Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• synthesis. This report reviews the combination of flow chemistry and inductive heating in industrial settings as well as academic research and demonstrates that the two technologies ideally complement each other. Keywords: catalysis; enabling technologies; flow chemistry; inductive heating; multistep

• flow conditions. In these reactions, the leaching of palladium was as low as 34 ppm for Suzuki–Miyaura reactions and 100 ppm for Heck reactions. Importantly, the functionalized nanoparticles could be reused several times without observing a decrease in catalytic activity. 3.2.4 Multistep processes: The

• inductive heating technology has also been used in multistep processes targeting drugs or important molecules in the fragrance industry. The first example deals with a metal-free carbon–carbon-bond formation process between tosylhydrazones generated from the corresponding aldehydes 74 and boronic acids 76

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• multistep procedure [33]. The synthesis of target compound 26 was accomplished in two steps by double esterification and elimination of 23. Dicarbonate 24 partially eliminated over C7–C7a to give 25 upon aqueous workup. In order to maximize the yield, the organic fraction containing a mixture of 24 and 25

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• formed by multistep reaction progression where, to overcome severe steric hindrance, two oxindole moieties are in trans orientation. HPLC data of compound 3o ensures >95:5 dr (Supporting Information File 1). The structure was further confirmed by NOESY spectra of compounds 3e (Figure 3) and 3j

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• (Mtb) [19]. Owing to the biological significance of 5-unsubstituted dihydropyrimidinones, a variety of multistep protocols has been reported for the synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones [20][21]. Typically, dihydropyrimidinones are obtained via a Biginelli reaction leading to an

Synthesis and bioactivity of pyrrole-conjugated phosphopeptides

• Qiuxin Zhang,
• Weiyi Tan and
• Bing Xu

Beilstein J. Org. Chem. 2022, 18, 159–166, doi:10.3762/bjoc.18.17

• ][51][52][53][54]. Being a multistep molecular process to generate non-diffusive peptide assemblies, EISA is a facile and useful approach to explore the emergent properties of peptide assemblies [55][56][57][58][59] in cellular environment. One of the most explored EISA processes is the use of alkaline

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• the initiation of a multistep reaction is through the generation of an organoiron species. This can occur by the oxidative insertion of a low-valent iron into a C–X bond (Scheme 2). Evidently, iron in low oxidation states may operate as an iron-centered nucleophile, and catalyze reactions involving

• various nucleophiles 108 (Scheme 22) [105]. This protocol offers an expedient approach to 1-amino-2-silylalkanes, a classically difficult framework to synthesize, typically requiring harsh reaction conditions, multistep synthetic routes, or the use of expensive silicon reagents [106]. Moreover, the

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• equivalent of aniline in the presence of a Brønsted acid undergoes a multistep rearrangement to form the indole group as part of the target tryptamine 110 (Figure 20). The one-pot conversions occurred successfully over a wide range of monosubstituted anilines, including various para-alkyl groups (65–72

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• attack of an olefinic double bond to the cationic centre Wagner–Meerwein rearrangements, and proton or hydride migrations [2]. These multistep cascade reactions ultimately result in terpene hydrocarbons that are often (poly)cyclic and contain several stereogenic centres [3][4]. In some cases, water is

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• multistep procedures requiring large amounts of toxic metal complexes [12][33][34]. Later improvements still demand prefunctionalization of the quinone substrate [35][36][37]. While effectively eliminating this requirement, CH bis-arylation using palladium complexes still suffers from regioselectivity

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• suitability as a potential vehicle to deliver these drugs. Disadvantage is however the multistep procedure to generate micelles ranging from the synthesis of block copolymers to the self-assembly into micelles, often in low dilution, making the process inefficient. Micelles obtained by the PISA process can in

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• activity for iodoethynyl groups [63]. Intramolecular cyclization In 2009, Swager’s research group published the synthesis of fluorescent macrocycles based on 1,3-butadiyne-bridged dibenzo[a,j]anthracene subunits via a multistep route (Scheme 30) [64]. They synthesized substituted dibenzo[a,j]anthracenes

• published in 2018, de Koning and co-workers reported a new methodology to synthesize the benzo[a]anthracene skeleton of angucycline derivatives 146 by using a multistep strategy based on Suzuki–Miyaura, isomerization, and ring-closing metathesis reactions (Scheme 33) [67]. The commercially available 2

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

• glycosylation or complicating the deprotection steps. Orthogonality and stability become particularly crucial when the goal is the multistep synthesis of long COS. Other glucosamine-based polysaccharides Other polymers of glucosamine based on the β(1–3) or β(1–6) linkages exist, but have gained less synthetic

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• exploitation of triazole rings as beneficial directing groups to produce complex triazoles has been screened. Although the postfunctionalization of disubstituted 1,2,3-triazoles may include multistep reactions for the synthesis of this kind of products, it is an easy and efficient strategy (Scheme 1). The

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

• ][23][24][25][26][27]. As such our aim is not to include a comprehensive review here but to simply highlight the principle characteristics and direct the reader to the listed references for further consultation. In overview a basic depiction of a sequential batch vs flow approach for a multistep

• reduction; there are many potential applications of this field in the small scale chemistry as well. For example, areas like combinatorial chemistry [33][34][35], complex multistep syntheses [14][36][37], synthesis of pharmaceutical substances have witnessed tremendous growth using flow chemistry approach

• reagents has also greatly aided in the development of impressive sequential multistep sequences in flow by acting as direct in-line quenching, work-up and purification steps [28][80][81][82][83][84][85]. Indeed, the scavenger approach to removing excess solution phase reagents or byproducts has had a

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

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

• ) have an enhanced thermal stability in DNA triplexes and duplexes, a high binding affinity to RNA, and are nuclease resistant [22][26][27][28]. These properties have led to LNA (BNA) being used in various therapeutic ONs that have reached clinical trials [29]. However, the multistep synthesis of LNA and

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• synthetic methods for secosteroids is wide. However, usually these are multistep sequences exploiting toxic oxidants. Marine invertebrates are a rich source of oxidated and highly functionalized steroidal metabolites, including secosteroids. Since the first isolation of 9,11-secosterol from

• synthetic schemes starts with natural steroids, taking advantage of the appropriate stereochemistry of existing stereogenic centres [16][17][18][19][20]. However, the synthesis of target compounds is a multistep procedure, often including several protections and deprotections of functional groups. Our

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• a variety of alkenes as an interesting heterogeneous system. This cobalt oxide mesoporous nanomaterial showed good activity and selectivity to the epoxide product and could be recovered and reused, but the multistep (not straightforward) synthesis of the catalyst and the use of DMF as the solvent

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• biologically relevant substrates contain a feruloylated ʟ-arabinofuranosyl moiety [12][15][16][17]. These structurally more complex compounds are obtained using multistep syntheses, considerably limiting the availability. Moreover, they might be specific to certain subcategories of feruloyl esterases [18][19

• chromogenic 5-O-feruloylated α-ʟ-arabinofuranosides 1a and 1b is usually achieved using a multistep pathway that involves trapping the furanose conformation, anomeric activation, glycosidation, regioselective deprotection of the primary hydroxy group, feruloylation, and final deprotection to yield the target

• evaluation of 12 as a chromogenic substrate for Fae assays To synthesize chromogenic (±)-4-O-(2-hydroxy-4-nitrophenyl)-1-O-trans-feruloyl-1,2,4-butanetriol (4NTC–linker–Fe, 12), which contains 4NTC bound via a cleavable linker to a ferulate motif, a multistep route was devised (Scheme 1). First, a shorter

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• first example of using Schwartz’s reagent-mediated partial reduction of lactams and the Ugi–azide multicomponent reaction in a tandem process. Yields of the described products are moderate to good, a satisfying result for such a multistep process. We have shown that such a reaction does not necessarily

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

• Vyacheslav I. Supranovich,
• Igor A. Dmitriev and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

• implies multistep protocols, since two distinct bond-forming reactions are necessary for the cycle formation. While mono- and difluorinated piperidines are well known, tetrafluorinated piperidines are rare [19]. At the same time, the chemistry of compounds containing the tetrafluoroethylene fragment

On the mass spectrometric fragmentations of the bacterial sesterterpenes sestermobaraenes A–C

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2020, 16, 2807–2819, doi:10.3762/bjoc.16.231

• a multistep process (Scheme 6A). Starting from 3•+, a hydride shift to n3•+ and skeletal rearrangement lead to o3•+. A subsequent hydrogen rearrangement of this primary radical yields the tertiary radical p3•+ that can undergo an α-fragmentation to q3•+, followed by hydrogen rearrangement to r3

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• nitrogen heteroatoms were synthesized in multistep synthetic routes. A Buchwald–Hartwig amination of brominated precursors, thermolysis of azide precursors, and a Cadogan reaction of nitro-substituted precursors were successfully applied to eventually build-up pyrrole rings to stable and soluble fused

• application in organic electronics. Results and Discussion Synthesis of N-alkylated S,N-heterotetracene 9 by Pd-catalyzed amination. Asymmetric S,N-heterotetracene Hex-SN4 9 comprises the sequence of heteroatoms ‘SSNS’ in the tetracyclic conjugated π-system [37]. In a multistep synthesis, 2,6

• -heterotetracene system SN4'' comprising the heteroatom sequence ‘SNNS’ is built-up by annulation of two ‘outer’ thiophene and two ‘inner’ pyrrole rings resulting in the symmetric sequence of heteroatoms in the tetracyclic conjugated π-system. The multistep synthesis of Pr-SN4'' 33 started from 2

Tools for generating and analyzing glycan microarray data

• Akul Y. Mehta,
• Jamie Heimburg-Molinaro and
• Richard D. Cummings

Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187

• comparison of glycan microarray data. We identify a variety of glycan microarray repositories where interested readers can find microarray data to build new software. We also highlight manual and automated data analysis tools. One must always be aware that the intrinsic complexity of the multistep process of

One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

• Haruyasu Asahara,
• Minami Hiraishi and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2020, 16, 1830–1836, doi:10.3762/bjoc.16.150

• [8][9]. However, these nitration methods are less effective because the yield of the desired product is reduced by the formation of regioisomers. Although the hydroxylation of 3-arylated-1-fluoro-4-nitrobenzene has also been reported as a related strategy, multistep reactions are necessary for