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

• economic perspective due to increased amounts of waste generation, toxic solvents, and no real-time control of pollution generated, etc. [4]. Therefore, in this connection, the multicomponent reaction (MCR) is one such approach where three or more reactants combine to form a single product retaining the

• synthetic as well as biological perspective owing to their plethora of pharmacological activities. They are potent anticancer (144), antimicrobial (145), and anticonvulsant agents (146, Figure 11) [129]. Their occurrence in various

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• conditions is highly desirable. From another perspective, compounds containing a 1,3-dicarbonyl moiety are essential building blocks in organic synthesis whose reactivity is well-established in the literature [34][35]. Besides, these are the precursors of β-enamines which are employed for the synthesis of

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

• processes, acid–base treatments as well as the production of fuels are not discussed, nor are the methods for the further upgrade of the depolymerisation products. Keywords: catalysis; depolymerisation; plastic; recycling; sustainable; Review 1. Introduction In a circular-economy perspective, wastes are

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• a chemical and biosynthetic perspective. Their emergence dates back to 1977 with a patent filing from The Upjohn Company describing an unidentified ‘antibiotic 354’ isolated as a fermentation product of Streptomyces puniceus subsp. doliceus; spectroscopic characterization, including 1H NMR data, was

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• of the molecular interactions and mechanisms that govern PPIs and their role in protein–protein complexes. We provided an outline on the different complexes known and how they are assembled. A clear perspective and a deeper understanding of these mechanisms and the roles of the complexes is

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• perspective, we herein disclose environmentally benign, atom-economical, catalyst-free nucleophilic additions of benzylic-like azaarene C–H groups to various benzaldehydes under neat conditions (Scheme 3). Results and Discussion With the purpose to develop an environmentally benign process, we first examined

Computational tools for drawing, building and displaying carbohydrates: a visual guide

• Kanhaya Lal,
• Rafael Bermeo and
• Serge Perez

Beilstein J. Org. Chem. 2020, 16, 2448–2468, doi:10.3762/bjoc.16.199

• carried out in structural glycobiology, typically using various software. In this perspective article, we outline developments in the computational tools for the sketching, visualisation and modelling of glycans. The article also provides details on the standard representation of glycans, and

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

• monosaccharide and linkages, and assigns each node weights depending on their binding to the ligand [49]. MCAW-DB offers a unique perspective to glycan array binding results and even takes into account gaps in structures. The tool has parameters (such as weighting) which may need to be optimized to work with

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• potential applications ranging from the chemistry perspective to materials science and technology [1][2][3][4]. As we know that bowled (curved) surfaces are universal in nature for example our planets as well as atomic orbitals possess the curvature which generally affects the charge-transport, redox, self

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• previously for benzylic fluorination [130]. In a later perspective [36], the authors speculated that the amide served as a directing group. Indeed, in situ-formed ammonium carbamates were recently identified to direct the HAT of a quinuclidinium radical cation [208]. 3.5 Scalability of C–H fluorinations That

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

• Rémi Martinent,
• Javier López-Andarias,
• Dimitri Moreau,
• Yangyang Cheng,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

• assessed for the standard cytometric CAPA, but a low precision and reproducibility were anticipated [62]. The high accuracy and selectivity promised that our image-based HC CAPA could expand the scope of the CAPA beyond HGM cells. To elaborate on this attractive perspective, HeLa cells were transiently

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• catalytic system is extremely appealing. In that perspective, the scope of this review aims to present innovative reactions combining C–H activation and visible-light induced photocatalysis. Keywords: C–H activation; C–H functionalization; dual catalysis; photoredox catalysis; radical chemistry

• . Furthermore, a peroxide (TBHP) is needed to oxidize the Ir-based photoredox catalyst and to generate the acyl radical via hydrogen atom transfer. From the mechanistic perspective this synergistic dual catalytic system merging C–H activation and photocatalysis is similar to the one described by Sanford for the

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• found to be slow reacting and produced 2aA in a lower yield (42%). From the perspective of green chemistry, one-pot reactions are preferred as less waste is generated due to the avoidance of work-up, isolation, and purification of intermediates [66]. Accordingly, the feasibility of a one-pot synthesis

Fluorohydration of alkynes via I(I)/I(III) catalysis

• Jessica Neufeld,
• Constantin G. Daniliuc and
• Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

• Hammett analysis in which the substitution of the iodoarene catalyst was explored (R = Me, H, Cl, and Br) revealed a build-up of positive charge (ρ < 0) during the rate-determining step (Figure 4B). From a methodological perspective, this study provides a conceptual platform to unmask the valuable α

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

• health. We conclude in Section 5 with a summary and our perspective on the future of HPCats in flow as a methodology for sustainable and scalable photosynthesis. 1.2 Importance of the review and brief historical perspective With growing socioeconomic and political pressure to act on anthropogenic

• found to split water to oxygen and hydrogen gas under strong UV irradiation. This gained significant attention in the wider scientific community for the potential generation of solar fuels [27][75] and formed the foundation of modern heterogeneous photocatalysis. With this brief historical perspective

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

• Alexander V. Nyuchev,
• Ting Wan,
• Borja Cendón,
• Carlo Sambiagio,
• Job J. C. Struijs,
• Michelle Ho,
• Moisés Gulías,
• Ying Wang and
• Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

• properties, for example, a high electronegativity (χ = 3.7), and a high lipophilicity (Hansch-Leo parameter π = 1.04, intermediate between the -CF3 and the -SCF3 values, respectively, 0.88 and 1.44) [4]. From a pharmaceutical perspective, the former property provides stability of the drug under physiological

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

• from a green chemistry perspective if the water can be reused. To this end, micellar chemistry is appropriate for cross couplings [19]. Residual water also assists ‘solvent-free’ methods [20]. In summary, the Suzuki–Miyaura reaction is a fantastically versatile and industrially important reaction [21

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• tolerated several functional groups, including bromine and nitrile units, which provide ample scope for further manipulation of the products from the perspective of medicinal chemistry. The catalyst can be easily recovered and recycled in a colloidal solid form, enabling catalytic recycling and reusability

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• hydroxy ester 4 followed by reaction with acetonitrile (CH3CN), a multistep approach would be less economical in industry (Scheme 1). Results and Discussion To date, the most economically appealing conditions from an environmentally friendly perspective entail relatively mild base-promoted (potassium tert

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• NMR spectroscopy. Compounds were irradiated until an increase in isomerization yield could no longer be observed (see Supporting Information File 1 for details). To set the results of this photoisomerization into perspective a noncyclic stiff stilbene was used as a reference (Scheme 4). The

Perspective isomorphs – a new classification of molecular structures based on artistic and chemical concepts

• Jannis Neumann,
• Ansgar Schnurr and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2019, 15, 2319–2326, doi:10.3762/bjoc.15.224

• -fertilization with natural sciences. Here we show a new classification of molecular structures, so-called perspective isomorphs, applying an interdisciplinary crossing of epistemological concepts between chemistry and art. The idea is based on the notion that molecules can be classified, if they appear

• equivalent from one standpoint in a specific orientation. We termed such a group of such molecules perspective isomorphs. The general concept is outlined together with a nomenclature system. Furthermore, this concept has been visualized by artistic representations of molecules. The concept of perspective

• isomorphs and its discussions herein will extend current models and stimulate the discourse about the nature of atoms and molecules and especially their models. Keywords: art and science; nomenclature; perspective; representation in chemistry; structure; Introduction Up to now, epistemological concepts of

Genomics-inspired discovery of massiliachelin, an agrochelin epimer from Massilia sp. NR 4-1

• Jan Diettrich,
• Hirokazu Kage and
• Markus Nett

Beilstein J. Org. Chem. 2019, 15, 1298–1303, doi:10.3762/bjoc.15.128

• recognition of a far greater taxonomic diversity of microbes that can produce bioactive compounds [1][2][3]. The exploration of previously neglected taxa has been demonstrated to bear significant potential for finding new natural products and is thus highly promising from a drug discovery perspective [4][5

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• . employing substitutional disorder, achieved the co-crystallization of six components [28]. As for positional disorder, it generally indicates the same molecule or assembly can adopt more than one favourable conformation. From this perspective, disorder can be considered as a special case of a co-crystal or

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• ligand H2L (M = divalent or trivalent transition metal). Right: Perspective view of the bowl-shaped structure of the corresponding carboxylato complexes. Synthesized compounds and their labels. 1H NMR spectrum of 6 in CD3CN at 295 K (1.0–8.0 ppm). The resonances and assignments are listed in Table 2 and

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• differentiated Lewis-basic binding sites, however, from a broader perspective, the nature of the DBTAA binding site can be easily switched into a Lewis-acidic one after appropriate metal insertion (e.g., with zinc(II) ions) [33]. The crown-capped DBTAA’s were synthesized by refluxing 1,4,10-trioxa-7,13