A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• hydroxy groups pointing towards the sides [1]. This makes the ‘hole’ in the donut a lipophilic cavity that in water can form complexes with small hydrophobic molecules [2] driven by the entropy increase by expulsion of water [3]. Compound 1 has a wide range of applications where the complexation of

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• against Gram-positive bacteria and compound 3ck against C. albicans were better than the reference drug norfloxacin. Keywords: acceptorless dehydrogenative coupling reaction; antibacterial; cyclometalated iridium complexes; quinolines; Introduction As an important class of heterocyclic compounds

• as raw material. In order to solve such problems, chemists have developed ADC reactions catalyzed by metal complexes (such as Ir [18][19], Ru [20][21][22][23][24], Re [25], Mn [26][27], Pd [28], Ni [29], Cu [30], etc.) to synthesize quinolines using o-aminobenzyl alcohol as starting material. ADC

• reactions have the advantages of high atom economy, simple operation, clean and green, and have become a research hotspot [31][32][33][34][35]. Cyclometalated iridium complexes with good catalytic efficiency and selectivity are very effective catalysts in ADC reactions. Moreover, these catalysts are easy to

Comparison of crystal structure and DFT calculations of triferrocenyl trithiophosphite’s conformance

• Ruslan P. Shekurov,
• Mikhail N. Khrizanforov,
• Ilya A. Bezkishko,
• Tatiana P. Gerasimova,
• Almaz A. Zagidullin,
• Daut R. Islamov and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1499–1504, doi:10.3762/bjoc.18.157

• [7]. It is important to know the conformational capabilities of such ligands for construction of such complexes [8][9][10][11]. However, to date, XRD data on phosphorus derivatives containing a ferrocenyl substituent at the sulfur atom are presented only in oxidized and sulfurized forms

• . Trithiophosphite has not been studied by X-ray diffraction analysis, although it is of great interest for the construction of complexes with multiferrocene systems. Herein we present for the first time X-ray diffraction data of (FcS)3P and compare it with DFT calculations to show which conformation are preferred

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• showcasing innovative research regarding supramolecular catalysis using macrocyclic and acyclic hosts, as well as other molecular architectures such as self-assembled capsules and metallocages. In their contribution, Secchi and Cera [15] reported the synthesis of diphosphine gold(I) calix[6]arene complexes

• in the field of the supramolecular catalysis on the use of discrete heteroleptic metallo-supramolecular complexes as catalysts. The idea of breaking/reducing symmetry has inspired many researchers to study heteroleptic metallo-complexes made up of various ligands. The authors emphasized the

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• hydrazone groups. The use of N-TAAD derivatives as potential ligands and receptors was showcased through forming boron chelates and host–guest complexes with water and simple alcohols. Keywords: azaadamantanes; cyclotrimerization; hydrazones; inclusion complexes; molecular recognition; Introduction

•  1b) [21][22][23]. In particular, N,N,N-trihydroxy-TAAD derivatives (3O-TAADs) were shown to be chelating ligands for boron [24]. The application of TAAD-boronate complexes was demonstrated by the preparation of conjugates of boronic acids with biomolecules [25][26], COF-like materials [25], and

• dynamic covalent libraries [25]. TAAD can be covalently bound to a polymer matrix through the nucleophilic nitrogen N(1) that was used to prepare scavengers of boronic acids [25]. Also, TAAD was demonstrated to serve as a scorpionate-type ligand for manganese and iron leading to complexes with the metal

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• key organic intermediates in the drug discovery and process chemistry [4][5][6]. Chiral metal–salen complexes were designed for catalyzing reaction processes that resulted in good yield, high regioselective and enantioselective control for the asymmetric ring opening of terminal epoxides. Various

• ]. Since their discovery, researchers have investigated several Co–salen complexes for the KR of epoxides with phenols as nucleophiles (Figure 1) [18][19]. Kim et al. described a catalytic system of a chiral Co–salen immobilized on meso/macroporous silica monoliths for the ring opening of epoxides [20

• synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalyst for the synthesis of α-aryloxy alcohols through the phenolic KR of terminal epoxides (Scheme 1). Indeed, advantages to break the C2-symmetry in Co–salen complexes were reported before [23][40]. In

Synthesis of meso-pyrrole-substituted corroles by condensation of 1,9-diformyldipyrromethanes with pyrrole

• Baris Temelli and
• Pinar Kapci

Beilstein J. Org. Chem. 2022, 18, 1403–1409, doi:10.3762/bjoc.18.145

• Baris Temelli Pinar Kapci Hacettepe University, Department of Chemistry, Beytepe Campus, 06800, Ankara, Turkey 10.3762/bjoc.18.145 Abstract A copper triflate-mediated approach to access copper complexes of pyrrole-substituted corroles from the reaction of 1,9-diformyldipyrromethanes and an excess

• with corroles, here we describe the first synthesis of copper complexes of trans-A2B-corroles possessing pyrrol-2-yl substituents at positions 5 and 15 by the condensation reaction of 1,9-diformylated dipyrromethanes with pyrrole in the presence of copper triflate. Results and Discussion At the

• complexes of A2B-type pyrrole substituted corroles. We believe that the placement of the polymerizable pyrrole as a conjugated substituent to the macrocycle is an important contribution to the polymerization of corroles and the expansion of the usage areas of these compounds. Further studies on the

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• hydrophilic outer surface and hydrophobic cavity. This cavity can encapsulate another lipophilic guest molecule and thus form an inclusion complex [3][4]. This phenomenon is reversible and leads to an equilibrium between encapsulated and free guest. A staggering number of inclusion complexes of CDs with

• easiest accessibility; besides, β-CD forms usually the strongest inclusion complexes compared to α-CD and γ-CD. The amino-β-CD was prepared according to published procedures [25][26][27]. Common commercially available volatile aldehydes 2a–j (Figure 2) were chosen as the aldehyde reactants. Some of the

• that CD-based pro-fragrances combine a chemical barrier, as the aldehydes are linked to the CD via imine bond, and a physicochemical (supramolecular) barrier, as we established that aldehydes formed inclusion complexes in aqueous solution with β-CD. We confirmed from the NMR kinetic study of the imine

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• mediator in the synthesis of asymmetric phosphines starting from white phosphorus [15]. Moreover, the presence of the lone pair of the P atom opens the route to polynuclear complexes [16][17][18] and coordination polymers [19][20][21] with the mixed σ-/π-coordination mode, which is not typical for

• replaced with phosphacyclopentadienyl ligands. Related diphosphacyclobutadiene complexes Fe(η4-P2C2R2)2 were oxidized much more cathodically (negative by 1.7–2.0 V) [46][47], which indicated a significant contribution of the phosphacyclopentadienyl ligands to the iron atomic orbitals. Of course the

• structures of 8 and diphosphacyclobutadiene complexes are not isolobal, but it would be interesting to study electrochemical properties of Fe(η5-P2C3R3)2 complexes in the future. For reduction, the electrochemical properties changed more noticeable since the contribution to the LUMO came from the

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• and emission takes place within the intrinsic region [2][3][4][5][6]. Two families of widely investigated emitters for LEECs are ionic transition metal complexes (iTMCs) [7][8][9][10] and conjugated polymers (CPs) [4]. From the early use of ruthenium(II) complexes, a significant amount of research has

• focussed on developing high-performance iTMC-based LEECs [11][12], with iridium(III) complexes typically showing the greatest potential. A detracting feature of many iTMC LEECs is the use of scarce noble metal complexes. Despite the enormous number of low molecular weight organic emitters designed for use

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• molecules (but also inorganic precursors, organometallic complexes, enzymes, monomeric units, or even polymers) in bulk and to provide the energy required for the system to react (Figure 1b and Figure 1c) [7][8][9][10][11][12]. At times, the methodological differences between both approaches seem to have

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• base complexes; stereoselective electrosynthesis; voltammetric testing; Introduction Electrochemistry provides a direct access to highly reactive species by means of harnessing electrons or electron holes as reagents [1][2]. This capacity can be efficiently exploited in organic synthesis for rational

• -cyclopropanated amino acids in the form of Ni(II)–Schiff base complexes were suggested [16][17][18][19], including electrochemical ones [15]. Cyclopropane-containing amino acids are important components of various pharmaceuticals [20][21] and bio-additives [22]. Meanwhile, the cyclopropane fragment not only

• Ni(II) coordination environment yielding structurally and functionally novel types of tailor-made amino acids. Results and Discussion Voltammetry study As models, a series of Ni(II)–Schiff base complexes containing α,α-cyclopropanated amino acids was synthesized (see Figure 1). Complexes 1–3

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• catalytic approaches [9]. Especially the combination with other transition metal catalysts (metallaphotoredox catalysis), such as nickel complexes, resulted in a vast number of new methods to achieve cross-couplings under mild conditions [10]. However, the conditions of these methods are often hard to

• combination of solid photocatalysts (i.e., semiconductors) and homogeneous nickel complexes are feasible, but the fact that the nickel complex is in solution reduces the benefits of packed-bed reactor types [19][23][24]. Recently, several bifunctional heterogeneous catalysts that combine the photo- and the

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• ) triazoloquinoxaline complexes as well as a new TIQ rhenium complex were synthesized. As a result, a small 1,2,3-triazoloquinoxaline library was obtained and the method could be expanded towards 4-substituted tetrazoloquinoxalines. The compatibility of various aliphatic and aromatic alkynes towards the reaction was

• investigated and the denitrogenative annulation towards imidazoloquinoxalines could be observed as a competing reaction depending on the alkyne concentration and the substitutions at the quinoxaline. Keywords: click reaction; CuAAC; denitrogenative annulation; imidazole; metal complexes; quinoxaline

• diversity of metal complexes incorporating 1,2,3-triazoles as ligands have been reported [16][17][18]. Triazole ligands with N-heterocycles such as Pyta (4-(2-pyridyl)-1,2,3-triazole) and related structures were employed to obtain novel metal complexes as catalysts [19][20] and imaging probes [21], as well

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• are fluorescent compounds. Based on the spin statistics, the fluorescent emitters can only use singlet excitons for light generation [5]. In contrast, phosphorescent materials based on metal complexes could achieve a high internal quantum efficiency (IQE) up to 100% through intersystem crossing (ISC

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

• reaction. Reactions with soluble metal complexes or metal nanoparticles, utilized in transition-metal catalysis, are often avoided, especially if the metal contamination in the product exceeds certain limits. This is particularly true for the pharmaceutical industry. A continuous flow protocol for

Mechanochemical halogenation of unsymmetrically substituted azobenzenes

• Dajana Barišić,
• Mario Pajić,
• Ivan Halasz,
• Darko Babić and
• Manda Ćurić

Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69

•  1) [51], the analogous complexes of L6 and L7 were prepared to investigate whether the halogenation of the para-halogenated azobenzene derivatives follows the reaction pathway of the bromination of L1. The molecular structures of the isolated monopalladated tosylate complexes I6-I and I7-I solved

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• heteromeric complexes by Issacs’ classification [32] of two main categories: (a) social self-sorting, which involves the assembly of different species, and (b) narcissistic self-sorting, which only involves aggregation of the same component. Over the past few years, a variety of social self-sorting protocols

• complexes by Chan using complementary ligand binding [39], sometimes combined with conformational regulation [40], and of Newkome/Li [41] applying mainly geometric complementarity [42]. Clever utilized shape complementarity [21] for building heteroleptic palladium(II) cages whereas Crowley developed a

• PYridine and Phenanthroline complexes [85][86]), HETPHEN (HETeroleptic bisPHENanthroline complexes [87]) and HETTAP (HETeroleptic Terpyridine And Phenanthroline complexes [88]) interactions (Figure 12). Due to the different amount of donor atoms about the metal ion, the binding strength will decrease in

Synthesis of a new water-soluble hexacarboxylated tribenzotriquinacene derivative and its competitive host–guest interaction for drug delivery

• Man-Ping Li,
• Nan Yang and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2022, 18, 539–548, doi:10.3762/bjoc.18.56

• molecule overexpressed in cancer cells, through host–guest competitive substitution since TBTQ-CB6 has a stronger binding affinity toward SM than MV and DOX. The host–guest interactions of the complexes of TBTQ-CB6 with MV, DOX and SM were investigated by NMR spectroscopy and fluorescence spectroscopy. The

• association stoichiometry of the complexes of TBTQ-CB6 with MV, DOX, and SM was found to be 1:1 with association constants of Ka = (7.67 ± 0.34) × 104 M−1, Ka = (6.81 ± 0.33) × 104 M−1, and Ka = (5.09 ± 0.98) × 105 M−1, respectively. The competitive substitution process was visualized by NMR titration. This

• (CXs), cyclodextrins (CDs), cucurbiturils (CBs), and pillararenes, are of particular interest because they can act as vehicles for anticancer drugs by either self-assembling into nanocarriers [14][15][16] or forming host–guest complexes with anticancer drugs [17][18][19][20]. Tribenzotriquinacene (TBTQ

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

•  6a). Subsequently, Takata and co-workers presented a highly diastereoselective synthesis of [2]rotaxane amine N-oxides via intercomponent chirality transfer (see Figure 6b) [53]. For the synthesis of the rotaxanes, complexes of hydroxy-terminated ammonium salts 28a–d and BINOL-based macrocycle (R)-12

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• highly efficient catalysts based on copper complexes of different types of chiral ligands, 2-(pyridin-2-yl)imidazolidine-4-ones (I–III), bis-oxazolines (IV–VII), or diamine (VIII) were chosen for the study (Figure 2). Furthermore, the modification of the structure of the prochiral aldehyde intermediates

• catalysts based on copper(II) complexes with chiral nitrogen ligands were chosen. Generally, chiral copper complexes possess many advantages valuable for the pharmaceutical industry. They exhibit low toxicity (compared to other metal-based complexes) and many of them exist in forms suitable for recycling

• -one derivative. Here, we extended the series of catalysts to include copper complexes with another six 2-(pyridin-2-yl)imidazolidin-4-ones Ia,b–IIIa,b [20][21][22], four bisoxazolines IV–VII [23][24], and as chiral diamine, the alkaloid (+)-sparteine VIII [25] (Figure 2). All Henry reactions were

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• power factories, containing many manufacturing units called chloroplasts. Briefly, the antenna molecules capture the light energy by using protein–pigment complexes and transfer it to the specialized reaction centers via the FRET process, where the excited state energy is transferred into useable

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• aminomethylphosphine complexes of Ru(II), Pd(II), and Co(II) with N,N-bis(diphenylphosphinomethyl)aminopropyltrietoxysilane (DIPAPTES) and the best yields were obtained using [(DIPAPTES)PdCl2] complex and silica supported [SiO2(DIPAPES)PdCl2] complex, in 52% and 59% yields, respectively (Table 1, entry 11). In both

• cases, the formation of product 10 was observed with conversions of up to 90% [57]. In another approach, Uruş and co-workers used graphene oxide (GO)-supported bis(diphenylphosphinomethyl)amino GO@CHONHRN(CH2PPh2)2MX2 (M:Pd(II) and Pt(II))-type complexes as heterogeneous nanocatalysts, with Pd(II

• ) complexes showing the best catalytic activities with high selectivity compared to the Pt(II) complex, leading to 95–99% conversion and 60–65% selectivity (Table 1, entry 12) [58]. Sönmez and co-workers applied mononuclear complexes of ruthenium(III), chromium(III), and iron(III) with Schiff base ligands as

Amamistatins isolated from Nocardia altamirensis

• Till Steinmetz,
• Wolf Hiller and
• Markus Nett

Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40

• featuring ligand groups with nitrogen or sulfur as donor atoms [4]. The siderophore–iron complexes are recognized by highly selective microbial transporters. Following their translocation into the cell, the bound iron is released via a reductive or hydrolytic mechanism [2] Members of the genus Nocardia are

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• which realizes for the construction of medium-sized saturated nitrogen heterocycles [21]. Although the process enables the rapid construction of saturated nitrogen heterocycles from acyclic precursors, it requires homogeneous precious transition metal complexes as photocatalysts. On the other hand