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

• porphyrin macrocycle contains two Ns and two NHs (from two pyrrolenine and two pyrrole units), both of which can act as supramolecular H-bond donor and acceptors and can promote metal-free catalysis. Additionally, due to their synthetic versatility, these macrocycles can be further functionalized to add

• that function as hydrogen-bond donors and acceptors. Additionally, the nitrogen atoms in the pyrrole units of the porphyrin structure can also act as Lewis bases, capable of donating electron pairs. These properties enable tetrapyrrolic macrocycles to act as effective binding sites or catalytically

gem-Difluorovinyl and trifluorovinyl Michael acceptors in the synthesis of α,β-unsaturated fluorinated and nonfluorinated amides

• Monika Bilska-Markowska,
• Marcin Kaźmierczak,
• Wojciech Jankowski and
• Marcin Hoffmann

Beilstein J. Org. Chem. 2024, 20, 2946–2953, doi:10.3762/bjoc.20.247

• , we observed a striking illustration of this phenomenon. A Michael addition involving gem-difluorovinyl and trifluorovinyl acceptors was successfully achieved, demonstrating high stereoselectivity. This selectivity was further elucidated through theoretical calculations. Using this methodology, a

• series of new α,β-unsaturated amides, both fluorinated and nonfluorinated, were synthesized. Keywords: gem-difluorovinyl Michael acceptors; Michael addition; trifluorovinyl Michael acceptors; α,β-unsaturated amides; Introduction The Michael reaction, characterized by the addition of stable carbon

• advancements have broadened the scope of Michael donors and acceptors to encompass fluorine-containing compounds, enhancing the reaction's utility in synthesizing fluorinated derivatives [7][8]. Shibata and colleagues pioneered the use of fluorinated Michael donors, notably achieving enantioselective addition

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• enhanced push–pull effect in this molecule due to the presence of a stronger acceptor. Furthermore, the energy of the LUMO of compound 3 is comparable to reported PDI-based acceptors which have been used in OPVs with PCE > 7% [34]. Crystallographic study Needle-shape crystals of compound 3b suitable for

• (EAs) of −4.11 eV, −4.09 eV, and −4.15 eV. Consequently, the estimated Efund are 1.27, 1.25 and 1.25 eV for 3a, 3b, and 3c, respectively. The EA value is in a similar range (from −3.70 to −4.30 eV) of some of the most widely used fullerene-based acceptors such as PC60BM and PC70BM [35], which suggests

• that the three materials might function effectively as electron acceptors. OFET device studies The electrical characteristics were confirmed by the fabrication of OFETs. Compounds 3a–c were deposited by spin-coating onto n-doped Si/SiO2/Au substrates. The device performance parameters are summarised in

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• been widely investigated in the past decades for application as fluorescent dyes [3][4][5], chirality inducers [6][7][8], acceptors for photoinduced electron transfer (PET) [9][10], and components of supramolecular assemblies [11][12][13][14]. Owing to the stable π-electronic systems showing unique

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• 15: d = 2.356 Å) and with F3 and H4 (13: d = 2.867 Å, 14: d = 2.849 Å, and 15: d = 2.886 Å). Does the halogen at C4 contribute to the stabilization within the crystal lattice? To answer this question, we have to look at the behavior of halogens as hydrogen bond acceptors (X···H) and nonbonding

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• Discussion Based on our previous experiences with low-reactive Michael acceptors [29], initial attempts were carried out using bifunctional squaramides, derivatives of cinchona. However, up to 45% yield of the desired product was obtained with poor enantioselectivity (14%, Scheme 2). Considering the

• %) and moderate enantioselectivity (68%). Moreover, the steric bias in proximity (E2, Scheme 3) or the subunit of the conjugated system (E3) of acceptors revealed the nucleophiles (1 and 3) were unable to reach the reactive center or to form a stable bond. Interestingly, when the reaction with bis

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• ] cycloaddition–retroelectrocyclization (CA-RE) between electron-rich alkynes and electron-deficient olefins [8]. The [2 + 2] CA-RE click reactions were employed to produce a variety of functional materials, such as nonlinear optical chromophores [9][10], super acceptors [11][12], ion sensing D–A systems [13

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

• Deepa Nair,
• Abhishek Tiwari,
• Banamali Laha and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177

• double Michael addition of γ,δ-unsaturated-β-keto esters or Nazarov reagents with suitable acceptors such as nitroalkenes or alkylideneazalactones [7][8][9][10]. From the perspective of an active methylene containing organic moiety, curcumin and its analogs serve as inexpensive and readily available

• strain destabilizes TSII where R is equatorial. Such a strain is avoided by R adopting axial orientation as in TSI, which is favoured, leading to the observed product 3. This has also been seen in previous cases where nitroalkenes and chalcones have been employed as acceptors in the reaction of curcumins

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• asymmetric preparation of chiral amines through the addition of nucleophilic partners [21][22] while the azaenamine character of some aldehyde-derived hydrazones has been demonstrated in the coupling with suitable electrophiles such as Michael acceptors [23][24]. Last but not least, the C=N bond of

• hydrazones can act as radical acceptors for the synthesis of functionalized amines or hydrazones through reductive functionalization [21][25][26] or oxidative C(sp2)–H functionalization [27][28], respectively. Consequently, given their rich reactivity profile, exploring new synthetic transformations of

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• used in a wide range of applications, namely as organic semiconductors [8], acceptors for organic solar cells [9][10], as fluorescent probes [11][12][13], or as photosensitizers for photodynamic therapy and antimicrobial photodynamic therapy [14][15][16][17]. DPP derivatives with improved performance

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• described isomers and expand the toolbox of electron-deficient aromatic compounds available to organic materials chemists. Keywords: electron acceptors; organic materials; polycyclic aromatic hydrocarbons; Introduction Aromatic diimides are ubiquitous molecular scaffolds that have served as the basis for

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• that these dopants can act both as a source of protons and proton acceptors, facilitating the intermolecular proton conduction. The rational of the strategy behind the use of amino- and hydroxyphenyl spacers is twofold: i) their inclusion in the structure separates the bulky phosphonate groups from the

pKalculator: A pK_a predictor for C–H bonds

• Rasmus M. Borup,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2024, 20, 1614–1622, doi:10.3762/bjoc.20.144

• combination with an ML model to predict a variety of properties. These properties encompass the site of metabolism [31][33], the strengths of hydrogen bond donors and acceptors [34][35][36], and the regioselectivity of electrophilic aromatic substitution reactions [14]. Building on the methodology from

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• -ones to a variety of Michael acceptors has emerged as one of the most powerful strategies to access enantioenriched pyrazole derivatives [10][11][12][13][14][15][16][17][18][19][20][21]. In the majority of these cases, the reactivities of the pyrazolin-5-one derivatives were harnessed under non

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• ) are known. However, ΔG cannot be predicted for halogen-bond acceptors other than chloride and a more general predictive model should include parameters to describe the Lewis basic halogen-bond acceptor. Conclusion In this work, we have compared the characteristics of monovalent, hypervalent, neutral

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• )], regenerating the [Ir(III)] catalyst and completing the catalytic cycle. Overman and co-workers [50] used tert-alkyl N-phthalimidoyl oxalates to produce alkyl radicals that were further reacted with various Michael acceptors (Scheme 13). The photocatalyst Ru(bpy)32+ and Hantzsch ester were essential for the

• oxalates and Michael acceptors. Visible-light-catalyzed and Ni-mediated syn-alkylarylation of alkynes. 1,2-Alkylarylation of alkenes with aryl halides and alkyl oxalates. Deoxygenative borylation of oxalates. Coupling of N-phthalimidoyl oxalates with various acceptors. Cross-coupling of O-alkyl xanthates

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• (FIDO, FIDS, C60) as electron-acceptors were compared, and the open-circuit voltage with FIDS was 0.16 V higher than that with C60. Keywords: C60; evaporable fullerene derivatives; organic photovoltaics; organic solar cells; thioketone; Introduction Fullerene is a carbon allotrope that has attracted

• derivatives have played an important role both in OPVs as electron acceptors and in PSCs as electron transport layers (ETLs) by efficiently accepting electrons and hindering the transport of holes [12][13][14]. During the past 10 years, considerable attention has been focused on functional fullerene

• evaporable fullerene derivatives as electron acceptors. FIDO exhibited the best performance, with VOC that was 0.18 V higher compared with C60. Although FIDS showed a lower performance due to its less-desirable BHJ structure in the OPV, it could still potentially be utilized in perovskite solar cells in the

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• with excellent properties as organic photovoltaic materials [9][10][11][12][13][14]. Furthermore, regioisomerically pure bis-functionalized fullerenes function better as electron acceptors in organic thin-film solar cells than mixtures of the corresponding regioisomers do [12][13][14]. Therefore

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• displaying some localization on the dicyanopyrazinopyrazine acceptor. Notably, compound 3a displays the highest orbital density separation between donors and acceptors – an attribute relevant to efficient intramolecular charge transfer processes. This aligns with the observed lower optical HOMO–LUMO gap for

Organic electron transport materials

• Joseph Cameron and
• Peter J. Skabara

Beilstein J. Org. Chem. 2024, 20, 672–674, doi:10.3762/bjoc.20.60

• Joseph Cameron Peter J. Skabara School of Chemistry, University of Glasgow, University Avenue, Glasgow, G12 8QQ, UK 10.3762/bjoc.20.60 Keywords: acceptors; electron transport material; electron-deficient; n-type; organic semiconductors; There has been much interest in developing electron

• react with acceptors to produce reducing radical species, capable of reducing organic electron transport materials with a low electron affinity [4][5]. It is not only in modifying the molecular structure to improve the electron accepting ability that there is innovation in new organic electron transport

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• oxyalkylation product 28. Li and co-workers described the activation of NHPI esters towards SET using a Lewis acid catalyst, allowing for the functionalization of styrene radical acceptors with nucleophiles that do not necessarily engage in hydrogen-bonding interactions, such as electron-rich (hetero)arenes [47

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• involved in the main indigo chromophore comprising a C=C double bond substituted by two acceptors and two donor groups (Figure 4) [18]. Notably, the benzene rings make just a small contribution to the chromophore. In other words, the primary chromophore of indigo consists of two intersecting merocyanine