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

• synthetic tool for the construction of functionalized molecules. Dating back to the 19th century, this reaction, though initially used for the synthesis of an alcohol and acid functionality from aldehydes, has henceforth proven useful to generate diverse molecular entities using both intermolecular and

• intramolecular synthetic strategies. Immense applications in the synthesis of hydroxy acids and esters, heterocycles, fused carbocycles, natural products, and others with broad substrate scope have raised profound interest from methodological and synthetic standpoints. The ongoing development of reagents

• , solvents, and technologies for the Cannizzaro reaction reflects the broader trend in organic synthesis towards more sustainable and efficient practices. The focus of this review is to highlight some recent advances in synthetic strategies and applications of the Cannizzaro reaction towards the synthesis of

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

• Mithu Roy Bitan Sardar Itu Mallick Dipankar Srimani Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India 10.3762/bjoc.20.119 Abstract Alkyl and acyl radicals play a critical role in the advancement of chemical synthesis. The generation of acyl and alkyl

• synthesis [4][5][6][7][8][9]. In the context of sustainable catalysis, visible-light-mediated chemistry is becoming a prominent viable option for radical transformations in the synthesis of biologically useful compounds due to the energy efficiency and environmental friendliness [10][11]. Recently, the

• and alkyl radicals, has shown great promise in the synthesis and functionalization of various organic molecules [15][16]. These carbon radicals can be generated in several ways. The first and most straightforward method is the homolytic cleavage of labile C–heteroatom bonds, especially alkyl halides

Rhodium-catalyzed homo-coupling reaction of aryl Grignard reagents and its application for the synthesis of an integrin inhibitor

• Kazuyuki Sato,
• Satoki Teranishi,
• Atsushi Sakaue,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai,
• Hiroyuki Takeda,
• Tatsuo Kinashi and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 1341–1347, doi:10.3762/bjoc.20.118

• heterocyclic or aliphatic bromides scarcely proceeded. A Rh(III)–bis(aryl) complex, which might be formed from RhCl(PPh3)3 and the aryl Grignard reagents, plays an important role in giving the homo-coupling products in this reaction. Furthermore, we applied the reaction to the synthesis of a novel inhibitor

• we thought that our homo-coupling reaction would be optimal for the synthesis of compound 10n. Indeed, compound 5n was successfully synthesized by the Rh-catalyzed homo-coupling reaction and subsequently oxidized by KMnO4 to give the desired product 10n in 38% yield over two steps (Scheme 5) [29

• Grignard reagents. Rh-catalyzed one-pot Ullmann-type reaction with bromobenzene under optimized reaction conditions. Synthesis of compound 10n as a candidate for an integrin inhibitor. Examination of various alkyl halides as an oxidant. Examination of various Rh catalysts and solvents. Supporting

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• ]isoxazolone derivatives with various hydrazines was studied. It was shown that the considered process includes formation of corresponding hydrazones followed by Boulton–Katritzky rearrangement. As a result, the general method for the synthesis of substituted 1,2,3-triazoles bearing an allomaltol fragment was

• hydrazones there is only one example of an Boulton–Katritzky rearrangement for a condensed heterocyclic system known in the literature (Scheme 1b) [20]. In this regard extension of this reaction to another annulated products is an actual task. Previously, the methods for the synthesis of a wide range of

• recyclization. The structures of one example of the 1,2,3-triazole derivatives and one synthesized pyrazolylisoxazole were established by X-ray analysis. The X-ray crystal structure of compound 4g (CCDC 2343878). Synthesis of various triazole derivatives using Boulton–Katritzky rearrangement. Synthesis of

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• a hydride donor [5][6][7][8]. On the other hand, aryl radical-involved hydroarylation would be a promising alternative for the synthesis of alkylarenes with high anti-Markovnikov selectivity [9][10]. Aryl halides have received increased attention as ideal radical precursors because of their

• chemical reagents; however, these methods have some drawbacks, such as reagent toxicity/stability and limited substrate scope [12][13][14]. While recent advances in photochemistry have remarkably expanded the synthetic utility of (hetero)aryl radicals in organic synthesis [15][16][17][18][19][20], visible

• 3pa and 3qa, respectively. In addition to the successful transformations of heteroaryl iodides with indole or pyridine cores (3ra, 3sa), the electroreductive synthesis of methaqualone derivatives was also achieved (3ta). Pleasingly, a series of electron-deficient alkene and styrene derivatives were

Sustainable tandem acylation/Diels–Alder reaction toward versatile tricyclic epoxyisoindole-7-carboxylic acids in renewable green solvents

• Ayhan Yıldırım

Beilstein J. Org. Chem. 2024, 20, 1308–1319, doi:10.3762/bjoc.20.114

• ][34][35][36][37][38]. In addition to their unique properties, vegetable oils are known to be useful as green solvents in many applications [39][40][41][42]. The evaluation of vegetable oils as alternative solvents in organic synthesis is very limited [43][44][45][46][47]. Synthetic chemists are still

• anhydride. This is a useful approach for the total synthesis of complex natural compounds, epoxyisoindole skeleton-based precursors for various polycyclic compounds, and bio-based homo- and copolymers [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97

• synthesis scheme of various epoxyisoindole-7-carboxylic acids synthesized using the reaction conditions given in Table 1, entry 4 are given in Table 2 and Scheme 1, respectively. In general, IMDAF reactions proceed with high stereoselectivity to form the major exo addition product, in contrast to

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• can calculate larger system (>500 atoms) containing transition metals more precisely [16][17]. Result and Discussion Synthesis of Cu-tethered square nanobrackets 1b A pyrene-based nanobracket 4b was synthesized via a one-pot Suzuki coupling followed by the formation of dipyrrin from the dialdehyde 3

• @(12,2)-SWNT complexes. Chemical structures of Cu-tethered tetragonal nanobrackets 1a and 1b. Synthesis of nanobracket 4. Reaction conditions: i) XPhos Pd G2, XPhos, B2(OH)4, KOAc, EtOH, 80 °C, 2 h; ii) Br-Ar-Br, K2CO3, tetrahydrofuran (THF)/toluene, 80 °C, 16 h; iii) trifluoroacetic acid (TFA), pyrrole

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

• the Te(II)-catalyzed benchmark dehydrogenative phenothiazination of phenols, a reaction that we discovered in 2015 [35][36][37], under analogous conditions as previously described [30][31][32]. The results are summarized in Scheme 2. The multistep synthesis and characterization of all Te-based

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

• Amol P. Jadhav Claude Y. Legault Department of Chemistry, Centre in Green Chemistry and Catalysis, Université de Sherbrooke, Québec J1K 2R1, Canada 10.3762/bjoc.20.111 Abstract We have developed an operationally simple method for the synthesis of dialkyl α-bromoketones from bromoalkenes by

• alternative reaction pathway. Keywords: bromoalkenes; bromoketones; hypervalent iodine; oxidative hydrolysis; Ritter-type; Introduction Organic synthesis heavily relies on oxidative transformations to facilitate chemical reactions. One popular method for achieving these transformations is using redox-active

• substituted substrate which resulted in a low yield of the desired product. Also, this method involved using a stoichiometric amount of HTIB for the transformation. α-Haloketones are 1,2-difunctionalized synthons which are very versatile and essential building blocks for their role in the synthesis of

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2024, 20, 1278–1285, doi:10.3762/bjoc.20.110

• use in different fields of chemistry like synthesis [4][5][6][7][8][9], catalysis [10][11][12][13][14] and materials science [15][16][17][18][19][20][21][22][23]. ILs generally consist of an organic cation [24], such as the imidazolium or ammonium ion and an inorganic anion like a halide anion or

• ionic liquid in addition to the possibility to introduce alkyl chains with varying length [30]. TAAILs have already been successfully used for the synthesis of nanoparticles and as solvents in catalysis [31][32]. Recently we have described the synthesis and physical properties of TAAILs which have been

• shows the influence of the electronegative fluorine atoms on the electrostatic potential of the cation. Conclusion Based on the synthesis of nine different 1-aryl-4,5-dimethyl substituted imidazoles we report a new class of ionic liquids with electron-donating and -withdrawing substituents, three

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

• normal-pressure and vacuum thermogravimetric analysis (TGA). Additionally, we conducted a comparative analysis of bulk heterojunction (BHJ) organic solar cells using the three evaporable fullerene derivatives investigated in this work. Results and Discussion The synthesis of FIDO was performed by

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• carbonyl compounds, such as dimethyl acetone-1,3-dicarboxylate and 1,3-diphenylacetone, and with 1,3-bis(silyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, allow for a convenient synthesis of a great variety of products. The regioselectivity and course of the reaction depends

• ) allow for the synthesis of complex products with formation of several bonds in only one step [1][2][3][4][5]. In contrast to non-activated acetone (1a), methylene-active compounds, such as 1,3-dicarbonyl compounds, are of considerable relevance as building blocks in domino reactions (Scheme 1). For

• phosphoranes were less studied in my group. Chromones are oxygen heterocycles which are of pharmacological interest and represent versatile synthetic building blocks which can undergo various types of domino reactions [24][25][26][27][28]. In 2001, Nehad N. R. Saleh in my group developed a new synthesis of

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

• with trifluoroacetoacetate [17], the synthesis from enaminoketones [18] and the gold-catalysed cyclisation of propargylanilines [19]. Aside from its pharmaceutical significance quinoline compounds have been reported as strongly fluorescent with applications as electroluminescence materials [20][21][22

• electronic push–pull interaction of the thiophene and the quinoline moieties via the alkyne. Finally, we focussed on the synthesis of tris-alkynylated quinolines starting from 3,4,8-tribromo-2-(trifluoromethyl)quinoline (11). Starting material 11 was synthesized in very good yield from quinolone 3 by

• bromination in position 3, followed by treatment of brominated intermediate 10 with phosphoryl bromide (Scheme 5) [34]. To our delight, the optimized conditions for the synthesis of alkynylated quinolines 6 could be applied also to the three-fold Sonogashira reaction of 11. However, the reaction time had to

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

• [30][31][32]. Due to the oxidative nature, the use as selenium source in the synthesis of arylchalcogen compounds, in particular diorganyl selenides, can be a challenging process that involves sequential formation of two C–Se bonds and reduction of a Se=O bond in a single-pot reaction. Further

• . have very recently reported the synthesis of the black solid 4,4'-selenodianiline without the use of catalysts, preactivation, or any blocking groups (Scheme 1) [37]. In contrast, Kim et al., utilizing a CuI-catalyzed reaction [38], have reported that 4,4'-selenodianiline is a pale brown solid, which

• due to N–H stretching of the polymer [43][44]. The peak appearing at around 3000 cm−1 corresponded to the aryl C–H stretching. The peaks observed at 1593 and 1479 cm−1 were associated with C=C and C=N stretching, respectively. The obtained result was further supported by solid-state synthesis of

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• chemists regarding process formation of new bonds and synthesis of new scaffolds. In drug discovery and development, medicinal chemists struggle everyday towards the creation of new synthetic methods, driven by the increasing complexity of the molecules and taking into consideration economic and social

• isatin-based Ugi reaction [16][20][21][22][23] and the potential of the bis-amide-oxindole type derivatives as anticancer agents, a second family was synthesized, and screened for their anticancer activities (Scheme 1B). Results and Discussion Synthesis Underlining sustainability and economically favored

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

• Naziha Tarannam,
• Prashant Kumar Gupta,
• Shani Zev and
• Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

• germacradienyl cation, and 1,11-cyclization resulting in the humulyl cation [14][15]. Deprotonation of the intermediate germacradienyl cation yields germacrene A, a doorway towards the synthesis of many eudesmane and guaiane sesquiterpene hydrocarbons through its reprotonation-induced transannular reactions

• (Scheme 1) [16]. As an alternative to deprotonation, the germacradienyl cation can be captured by water to yield the sesquiterpene alcohol hedycaryol, which is an important intermediate towards the synthesis of sesquiterpene alcohols [17]. The reprotonation of (R)-(+)-1 germacrene A or hedycaryol at the

• stereochemistry. Theory is an important tool in understanding the complex chemistry in terpene synthesis. Gas-phase and in-enzyme tools have been employed extensively to understand terpene chemistry in general and terpene synthases in particular [21][22][23][24][25][26][27][28][29]. In the current work, we

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

• , controlling the regioselectivities of multiple functionalizations of fullerenes for the selective synthesis of specific multi-adducts poses an important challenge. Addition reactions of C60 are well known to occur mainly at the 6,6-bonds (junction between two hexagons) rather than at the 5,6-bonds (junction

• -silylene adduct 3 of C60 based on spectroscopic measurements, X-ray crystallography, electrochemical analyses, and theoretical calculations. Results and Discussion Synthesis of bis-silylene adduct 3 The synthesis of the silylene adduct was conducted using a modified literature procedure [15]. A degassed

• period of 200 ms, and a scan rate of 50 mV/s. Synthesis of 3. A degassed solution of Dip2Si(SiMe3) (30 mg) and C60 (4.6 mg) in toluene (20 mL) in a quartz tube was irradiated by a 125-W low-pressure mercury lamp for 2 h [15]. After the photolysis, 2 (22% yield) and 3 (36% yield) were isolated by flash

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

• classical Nazarov reaction. With the growing environmental concern and the need to use green reagents, interest in the use of bismuth in organic synthesis has increased significantly, as is reflected by the large number of works dedicated to this topic [52][53][54]. In addition to the replacement of toxic

• synthesis has been reported for several transformations, such as epoxide opening [56], ketal formation and deprotection [57][58], Mannich reaction [59], intramolecular Sakurai cyclization [60], alcohol oxidation [61], aromatic hydrocarbon nitration [62], imine allylation [63], Knoevenagel condensation [64

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• reactions via hydrogen auto-transfer, emphasizing the importance of this methodology and manganese catalysts in sustainable synthesis strategies. Keywords: alcohols; alkylation; amines; borrowing hydrogen; hydrogen auto-transfer; manganese; Introduction The construction of C–C and C–N bonds is of utmost

• importance in organic synthesis and is widely used in the pharmaceutical and other chemical industries. Palladium-catalyzed cross-coupling reactions are one of the compelling methods for building C–C and C–N bonds [1][2]. However, using organohalide reagents and harsh reaction conditions in this process

• are of substantial importance for the fine chemical industry, pharmaceuticals, agrochemicals, dyes, and natural products [25]. The synthesis of amine derivatives can be accomplished using many powerful techniques, including Buchwald–Hartwig and Ullmann cross-coupling reactions, hydroamination

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

• -di(2’,4’,6’-triethylphenyl)isobenzofuran are significantly less reactive than 1,3-diphenylisobenzofuran toward the strong dienophiles DMAD and acrylonitrile. The insights gained here suggest that the synthesis of large, persistent, kinetically stabilized isoacenofurans with unusually small HOMO–LUMO

• gaps is achievable. As such, these molecules deserve increased attention as potential p-type organic semiconductors. Keywords: acene; DFT calculation; highly delocalized π-system; isoacenofuran; isobenzofuran; kinetically stabilized; organic semiconductor; small HOMO–LUMO gap; synthesis; Introduction

• interesting class of organic semiconductors. Hamura and co-workers pioneered the synthesis of large isoacenofurans. They prepared a pair of 1,3-diarylisoanthracenofurans [3] and a pair of 1,3-diphenethynylisoanthracenofurans [4], and impressively utilized the latter as intermediates for the synthesis of

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

• inhibition of APOBEC3A was observed for modified DNAs. Although this shows that the negative charge is poorly accommodated in the active site of CDA and APOBEC3, the synthetic route reported here provides opportunities for the synthesis of other derivatives of phosphapyrimidine riboside for potential

• , IV), with an inhibition constant (Ki) of 0.9 nM (Figure 1B) [45]. However, it is unstable in solution and thus cannot be used as CDA inhibitor or incorporated into ssDNA and evaluated as an A3 inhibitor. Here, we report the synthesis of novel inhibitors of CDA and A3 based on the 1,4-azaphosphinine

• ssDNA. Results and Discussion Synthesis of nucleosides It is more straightforward to start the synthesis of a modified nucleoside from the assembly of a nucleobase that can be coupled to the sugar afterwards using the Hilbert–Johnson reaction or a silyl variation of it as described in the literature [65

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

• 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

• the synthesis of aryl-cored polybromides obtainable from xylenes or mesitylene. The selected targets are those of heightened interest to the scientific community, identified as those with a score of at least 100 reaction hits in the Scifinder® search (Figure 3). Results and Discussion As p- and o

• reports of ring bromination by means of NBS or the peroxide-bromide method are also known, but mainly for highly activated arenes (phenols or anisoles, for instance) or for the synthesis of monobromides [49][50][61]. Continuing our investigation on the subject, the ring bromination of p-xylene (3, Figure

Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines

• Vladislav V. Nikol’skiy,
• Mikhail E. Minyaev,
• Maxim A. Bastrakov and
• Alexey M. Starosotnikov

Beilstein J. Org. Chem. 2024, 20, 1069–1075, doi:10.3762/bjoc.20.94

• Vladislav V. Nikol'skiy Mikhail E. Minyaev Maxim A. Bastrakov Alexey M. Starosotnikov N.D. Zelinsky Institute of Organic Chemistry RAS, Leninsky prosp. 47, 119991 Moscow, Russia 10.3762/bjoc.20.94 Abstract An efficient method for the synthesis of isoxazolo[4,5-b]pyridines has been developed on

• Figure 1. A number of isoxazolo[4,5-b]pyridines has been described in patents, however, there are only a few methods for their synthesis reported in the literature. First representatives of this heterocyclic system were described by Gewald et al. in 1980 [14]. The known methods are usually based on

• isoxazolo[4,5-b]pyridine core synthesis have been summarized in a microreview [22]. Here, we wish to report an efficient method for the synthesis of isoxazolo[4,5-b]pyridines bearing electron-withdrawing groups (EWG) at positions 3 and 6 starting from readily available 2-chloro-3-nitro-6-R-pyridines as

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• by employing chemical photoswitches in molecular solar thermal (MOST) energy storage systems is a topic of appealing research interest. However, incorporating all the features desired for an ideal MOST system in a single photoswitching couple is challenging. Inspired by experimental synthesis, herein

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

• 73019, United States 10.3762/bjoc.20.92 Abstract Presented here is the design, synthesis, and study of a variety of novel hydrogen-bonding-capable π-conjugated N-heteroacenes, 1,4-dihydropyrazino[2,3-b]quinoxaline-2,3-diones (DPQDs). The DPQDs were accessed from the corresponding weakly hydrogen

• constructed via intermolecular N–H∙∙∙N interactions. However, vacuum-deposited films afforded poor hole transport. In separate work, Bunz et al. reported the serendipitous and understated synthesis of an H-bonding capable 1,4-dihydropyrazino[2,3-b]quinoxaline-2,3-dione (Figure 1a) [23]. In 2018, Takeda et al

• . reported the synthesis, electronic characteristics, and liquid-crystalline properties of several electron-accepting acenes, including 1,4-dihydropyrazinoquinoxalinediones (Figure 1b). The incorporation of strong hydrogen-bonding interactions facilitated the formation of a highly ordered liquid-crystalline