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

• -phenylpent-1-en-3-one (1k) as α,β-unsaturated ketone. The corresponding product, 3ka was obtained in 91% yield and 95% ee. Moreover, ethyl (E)-5-oxohex-2-enoate (1l) also showed good reactivity and the expected product (−)-3la was isolated in 68% yield and 95% ee. Next, we explored the scope of pyrazolin-5

Tetrabutylammonium iodide-catalyzed oxidative α-azidation of β-ketocarbonyl compounds using sodium azide

• Christopher Mairhofer,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1510–1517, doi:10.3762/bjoc.20.135

• any conversion under these conditions. The later limitation shows a clear difference between our methodology and Uyanik’s and Ishihara’s protocol [31], underscoring the higher reactivity of their designer catalyst (Scheme 1B). Having established the TBAI/DBPO-mediated α-azidation using NaN3, we also

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• addition of 2 to the allenoate instead, thus resulting in two complementary catalyst-controlled pathways [18]. Based on these previous results, and also the well-documented different reactivity trends of allenoates 3 when using different organocatalysts and activation modes [23][24][25][26][27], we were

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

• Yukang Wang,
• Yan Yao and
• Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

• , experiments using stoichiometric Cu(II) and Ce(IV) indicated that the radical decarboxylative cyanation reaction can only occur under light irradiation. In contrast, reaction with Ce(III) exhibited nearly no reactivity, demonstrating the crucial roles of anodic oxidation and light irradiation to the

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

• Ziya Dağalan,
• Muhammed Hanifi Çelikoğlu,
• Saffet Çelik,
• Ramazan Koçak and
• Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

• ] and many more (Figure 1). On the other hand, with unusual geometry and high reactivity norbornadiene and benzonorbornadiene derivative bicyclic compounds attract great attention by researchers with their use as building blocks in different application areas such as polymers, solar energy storage

Rapid construction of tricyclic tetrahydrocyclopenta[4,5]pyrrolo[2,3-b]pyridine via isocyanide-based multicomponent reaction

• Xiu-Yu Chen,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2024, 20, 1436–1443, doi:10.3762/bjoc.20.126

• carbon atom of isocyanide has both a lone electron pair and empty orbitals, so it has outstanding electrophilic and nucleophilic reactivity. At the same time, isocyanide also has good coordination ability to coordinate with metals to form diverse metal complexes [1][2][3]. Therefore, isocyanides have

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

• the theoretical framework describing the structure, bonding, and reactivity of diarylhalonium compounds [27]. Although some relativistic effects of astatine may not be sufficiently incorporated in calculations [28], others have shown in theoretical and limited experimental studies that astatine does

Challenge N- versus O-six-membered annulation: FeCl₃-catalyzed synthesis of heterocyclic N,O-aminals

• Giacomo Mari,
• Lucia De Crescentini,
• Gianfranco Favi,
• Fabio Mantellini,
• Diego Olivieri and
• Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

• -hydrazino form [17][24][25], we conceived the idea of reversing the reactivity of 4a–r in the six-membered cyclization process (N- vs O-annulation) through the generation of an electrophilic oxocarbenium [26][27] cation intermediate from the acetal residue at N-3 of the (thio)hydantoin core. To pursue our

Hypervalent iodine-catalyzed amide and alkene coupling enabled by lithium salt activation

• Akanksha Chhikara,
• Fan Wu,
• Navdeep Kaur,
• Prabagar Baskaran,
• Alex M. Nguyen,
• Zhichang Yin,
• Anthony H. Pham and
• Wei Li

Beilstein J. Org. Chem. 2024, 20, 1405–1411, doi:10.3762/bjoc.20.122

• of handling, and versatile reactivity, etc. render these catalysts highly attractive for adoption in organic synthesis. In particular, the field of olefin difunctionalization, known for its rapid assembly of molecular complexity, has been a fertile ground for innovation for hypervalent iodine

• , which then partitions into an ion pair suitable for olefin activation, followed by the addition of the bifunctional anionic carbamate (Scheme 1c). Our hypothesis here aims to directly access the reactivity of the cationic hypervalent iodine catalyst through an initial activation first, which we reason

Synthetic applications of the Cannizzaro reaction

• Bhaskar Chatterjee,
• Dhananjoy Mondal and
• Smritilekha Bera

Beilstein J. Org. Chem. 2024, 20, 1376–1395, doi:10.3762/bjoc.20.120

• Cannizzaro disproportionation, forming the hydroxy acid product 38, using a strong base [83]. On the other hand, the analogous 1,2-vicinal isomer 36 and the monoaldehyde 37 failed to produce any fruitful results. This difference in reactivity was referred to the relative positions of the formyl groups in the

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

• irradiation to harness the reactivity of alcohols and acids both upon derivatization and through direct use. By exploring recent advancements in deoxygenation reactions and the design of potential reactants, we aim to give an overview of the diverse strategies that highlight the unique reaction design and

Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

• Zining Li,
• Sana Jindani,
• Volga Kojasoy,
• Teresa Ortega,
• Erin M. Marshall,
• Khalil A. Abboud,
• Sandra Loesgen,
• Dean J. Tantillo and
• Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

• intrinsic properties, which result in protonation-initiated cyclization, Cope rearrangement, and atropisomerism. Finally, we exploited the reactivity of the trans-eunicellane skeleton to generate a series of 6/6/6 gersemiane-type diterpenes via electrophilic cyclization. Keywords: atropisomer; Cope

• collected NMR data of 1 in chloroform [5], but when we dissolved 2 in chloroform for NMR, it cyclized into two 6/6/6-tricyclic diterpenes (5 and 6) [7]. We discovered that 2 was much more sensitive to acid than 1 and eventually took advantage of its reactivity to determine its absolute configuration [7

• , leading to the predicted overall barrier of 32.5 kcal mol−1 and consistent with the diminished reactivity observed experimentally. The two lowest energy conformers of 1 (−3.2 and −3.0 kcal mol−1 relative to the DD conformer mostly likely to undergo Cope rearrangement) would both require significantly

Phenotellurazine redox catalysts: elements of design for radical cross-dehydrogenative coupling reactions

• Alina Paffen,
• Christopher Cremer and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2024, 20, 1292–1297, doi:10.3762/bjoc.20.112

• ]. In the present study, we decided to revisit the design of the phenotellurazine redox catalyst, in the hope of improving it as well as enabling new catalytic reactivity. In particular, we wished to investigate and optimize the level of electronic cooperativity between the Te- and N-centers, the effect

• in the structure, or else at different positions, in order to establish how their redox catalytic reactivity might be affected. Indeed, we learned recently that amino-arenes possess some level of redox catalytic activity by themselves, in the absence of a Te-center [34], and therefore wished to

• chemical stability, to such an extent that it could be in large part recovered at the end of the reaction (see previous study) [33]. In other words, PTeZ2 (2-methoxy substituent) features the best compromise in terms of electronic effects, which affect both the stability and reactivity of the key

Oxidative hydrolysis of aliphatic bromoalkenes: scope study and reactivity insights

• Amol P. Jadhav and
• Claude Y. Legault

Beilstein J. Org. Chem. 2024, 20, 1286–1291, doi:10.3762/bjoc.20.111

• reported to access bromoalkenes such as 1 from easily accessible substrates, making the approach even more appealing [31][32]. Results and Discussion Given its low volatility, we initiated our studies by testing the reactivity of (E/Z)-1,8-diphenyl-4-bromooct-4-ene (1a) with HTIB (1.1 equiv) and cat

• ’. Unfortunately, while it eliminated the side products, it further limited the yield for α-bromoketone, whereas no reactivity was seen when EtOAc and DMA were used as solvents (Table 1, entries 7–9). The use of HFIP led to complete conversion of 1a, but no observation of the desired product 2a (Table 1, entry 10

• iodine source, which resulted in a significant decrease in the yield of 2a (Table 2, entries 4 and 5). Importantly, when analogous chloroalkene (E/Z)-1,8-diphenyl-4-chlorooct-4-ene (1a’) was tested as a substrate under optimal conditions (without H2O or with 5 equiv H2O), no reactivity was seen at all

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

• bond length may have caused the higher reactivity and lower degradation temperature of t-Bu-FIDS compared with t-Bu-FIDO. Electron-accepting ability is one of the most important properties for fullerene derivatives, and it is typically described in terms of the energy level of the lowest unoccupied

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines

• Stefan Jopp,
• Franziska Spruner von Mertz,
• Peter Ehlers,
• Alexander Villinger and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1246–1255, doi:10.3762/bjoc.20.107

• 2,6-bis-alkynylated quinolines 9 were obtained in good yields of 77–85%, except for 9c containing a cyano group (20%), most likely due to its low solubility. The yields are generally lower as compared to isomeric 2,8-bis-alkynylated products 6a–g, which might be due to a slightly lower reactivity of

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• triplet reactivity of the Aza-H photocatalyst through spectroscopic measurements. The careful characterization of the versatile Aza-H photochemistry might contribute to the development of a new class of photoactive catalysts that can compete with traditional metal complexes and well-known organic

• its photochemical reactivity. The main reaction class catalyzed by excited-state polyazahelicene Aza-H so far is the redox-neutral addition of sulfinates and cyanopyridines, under elimination of cyanide, to styrenes in a three-component reaction. The proposed mechanism was derived from the redox

• photocatalyst (PC•+/PC = +1.12 V vs SCE) is then regenerated by an electron transfer from sodium p-toluenesulfinate (TsNa) (Ts•/Ts− = +0.70 V vs SCE) closing the photocatalytic cycle [45]. Unlike other prominent photocatalysts, little to nothing is known about the reactivity, the photophysical properties or the

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• arylamine reactivity. The NBO analysis was carried out using the same basis set, B3LYP/6-31G(d,p). The natural charge (q) of the nitrogen atom, occupancy of the nitrogen lone pair orbital, second-order perturbation energy (E) for intramolecular donor–acceptor interactions, and the donation of electron

• . Conclusion Aniline and o-anisidine underwent a predominant oxidative polymerization reaction with SeO2. Therein, electrophilic selenation was poor. The reactivity of the NH2 unit towards oxidation could be partially suppressed by the presence of an electron-withdrawing function. Consequently, for methyl

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

• 3cis-2 and 3cis-3 are unstable. Therefore, we next investigated the structural and electronic properties of the calculated mono-adduct 2a to evaluate its reactivity toward 1. The bond lengths of the cage C–C double bonds and the π-orbital axis vector (POAV) [49] of the cage carbon atoms of 2a are

• difference except for the carbons adjacent to the addition site. Therefore, neither the double bond lengths nor the POAV values of 2a are regarded as affecting the regioselectivity. The frontier orbitals of 2a were then examined to elucidate the reactivity in the second silylene addition. The ground states

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• reaction of aryl vinyl ketones, leading to the synthesis of 3-aryl-2-ethoxycarbonyl-1-indanones and 3-aryl-1-indanones. By changing the temperature and reaction time, it was possible to modulate the reactivity, allowing the synthesis of two distinct product classes (3-aryl-2-ethoxycarbonyl-1-indanones and

• -indanones. The reactions were catalyzed by bismuth triflate, an environmentally friendly metal. By simply changing the temperature and reaction time, it was possible to modulate the reactivity. In this methodology, no additives were used, and the reaction was insensitive to both air and moisture. To the

• reactivity of 9dc,dl. Supporting Information Supporting Information File 26: Experimental section and copies of 1H and 13C NMR spectra of all new compounds. Funding The authors thank the São Paulo Foundation Science (FAPESP, #2018/02611-0, #2013/07600-3 and #2023/18007-3, to FC) for financial support. F. C

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• spectroscopy. After 51 hours of reaction in boiling CH2Cl2, Diels–Alder adduct 27 was observed in 22% yield. Compound 27 was identified by 1H NMR and 13C NMR spectroscopies as well as high-resolution ESI mass spectrometry. Although the lack of reactivity observed for 3 and 23 limited our kinetic analysis, we

• -plane. The out-of-plane rotations provide for enhanced steric congestion both above and below the most reactive 1,3-carbons of the furan ring, dramatically reducing their reactivity with dienophiles including DMAD, acrylonitrile and singlet oxygen. Due to these non-planar conformations, the HOMO and

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

• Maksim V. Kvach,
• Stefan Harjes,
• Harikrishnan M. Kurup,
• Geoffrey B. Jameson,
• Elena Harjes and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

• accelerated by enzymes. These enzymes share a similar mechanism of cytosine deamination and a similar tertiary structure. Despite this similarity, individual enzymes are selective for the corresponding cytosine-containing substrates with little or no cross-reactivity. Cytosine deaminase, which is present in

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• desired reactivity. Substitution of a hydrogen atom with a halogen atom within an organic skeleton significantly increases the electrophilicity of the linked carbon centre, enhancing concerted (SN2) as well as carbenium ion-mediated (SN1) substitutions, common – for instance – on benzylic positions

• bonds of aryl halides also exhibit high reactivity, particularly towards transition-metal-mediated cross-coupling processes or Ar-SN reactions. Benzyl and aryl halides, collectively referred to as 'aryl-cored halides', have found extensive applications across various fields, including synthesis [1

• results on various substrates, the direct use of molecular bromine poses sustainability challenges. Its innate reactivity requires stringent safety protocols during transportation, storage, and handling [24]. A related concern involves the stability of the diluting media, often requiring the use of toxic

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

• high reactivity of intermediate 7a (Scheme 4). After optimizing the successful synthesis of alkoxylated and diketone derivatives of 7a, we were intrigued to investigate whether other dicyanopyrazinoquinoxaline derivatives could undergo a similar transformation. To assess the efficacy of the reaction

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• attractive class of reagents due to their stability, accessibility, and diverse chemical reactivity [1]. Diaryliodonium(III) salts, in particular, have been widely recognized as efficient arylating reagents for a range of carbon, nitrogen, oxygen, sulfur, and other nucleophiles, and can be employed in the

• modifying their physical properties, and stability and controlling the reactivity of arylation processes, as demonstrated in various studies [9][10]. For instance, the Gaunt group reported that the use of a fluoride counterion in diaryliodonium(III) salt can trigger phenol O-arylation by activating the

• ] nucleophiles due to their excellent reactivity and aryl group selectivity over aryl(anisyl)iodonium(III) salts [32] and aryl(mesityl)iodonium(III) salts [33]. Based on our previously reported conditions for the synthesis of diaryliodonium(III) salts [21], we designed a more practical synthetic protocol for the