Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• -b]furan-2-one, has been recently identified as an extremely efficient neuroprotective butenolide. Herein, we report the targeted synthesis of this compound as well as new synthetic protocols toward a class of compounds derived from 2H-furo[2,3-c]pyran-2-ones (karrikins) via bioisosteric exchange of

• until recently. In 2019 a study of Naidoo et al. [20] reported naturally occurring karrikins as compounds with moderate inhibitory activity against both types of monoamine oxidases (MAO-A and MAO-B) and acetylcholinesterase, while the sulfur bioiostere 3-methyl-2H-thiopyrano[3,4-b]furan-2-one (8) [21

• ] exhibited excellent activity. No targeted synthesis of 8 exists; it was isolated in low yield as a side-product in the synthesis of KAR1 (1) [21]. In this reaction sequence, thiopyranthione 6b is the side-product in the pyranthione 6a synthesis and both analogues were progressed to the final furan ring

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• synthesized α-phenoxyketones 4 in this reaction. The results showed that instead of benzo[b]furan formation, α-ketol rearrangement of phenoxyketones 4a,f occurred to afford β-phenoxyketones 9a,b in 55–60% yields (Scheme 10). Conclusion We have shown that the main direction of the reaction of bromopropargylic

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

• -benzoquinones and p-hydroquinones or the synthesis of menadione (10). The furan derivative 34 was used as a diene and 2-iodophenyltrifluoromethanesulfonate (35) as a dienophile, in the presence of n-butyllithium, forming 10 in 55% yield (Scheme 8) [92]. In the same year, Gogin and and co-workers developed a

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• )) (10 nm)/X wt % DICzTRZ or ICzTRZ: CzSi (20 nm)/PPF (2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan) (5 nm)/TPBi (1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene) (50 nm)/Liq (lithium quinolin-8-olate) (1 nm)/Al (80 nm), where X is 20 or 30. The PVK layer is applied to facilitate hole injection from

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• the furan framework. Following Fe-catalyzed oxidation, the resulting oxonium cation can be deprotonated to afford the final dihydrofuran. Further, this inter-/intramolecular radical addition/cyclization methodology has been applied for the synthesis of various substituted dihydropyrans [100][101] and

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• ; 19F NMR (565 MHz, CDCl3) δ −61.66 (CF3); FTIR (ATR) ν: 3085 (ν OH), 1625 (ν CH=N), 1113 (ν C-O) cm−1; HRMS–ESI (m/z): [M + H]+ calcd for C23H15F3N3O3, 438.1060; found, 438.1059. (E)-2-(((2-(Furan-2-yl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenol (3fa): Brown solid, yield 80%; mp 205–209 °C

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• compounds with heterocyclic substituents are of high biological and medicinal relevance [34][35]. Therefore, we have decided to evaluate sulfinylurea and thiourea catalysts C1 and C2 also with (E)-2-(2-nitrovinyl)furan (9) and (E)-3-(2-nitrovinyl)pyridine (11) as Michael acceptors. As Michael donor, we

• chose 3-phenylpropanal (6c). The Michael addition of 3-phenylpropanal (6c) with (E)-2-(2-nitrovinyl)furan (9) under initial reaction conditions with (S,R)-C1 (10 mol %) in THF/H2O with NMM as the base and with PhCO2H as acid additive gave product 10a in 31% yield after 72 hours with a diastereomeric

• )-2-(2-nitrovinyl)furan (9) and they provided racemic adduct 12 in 14 or 64% yield with poor or no diastereoselectivity (Table 2, entries 1 and 2). The change of solvent made it possible to obtain the products in a shorter time. Reactions catalyzed with 3 mol % (S,R)-C1 and (S,S)-C1 in MeCN gave

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• ][28][29]. In industry, pyrrole mainly comes from the extraction of coal tar, the condensation reaction of furan and ammonia under high temperature, or the cascade cyclization reaction of acetylene, formaldehyde, and ammonia. In the laboratory, there are many efficient methods for the synthesis of

• reaction of 2-trifluoromethyl-1,3-enynes 36 with aliphatic primary amines and the following NXS-mediated oxidative cyclization (Scheme 13) [57]. The method tolerated various substituted benzylamines, 2-phenylethanamines, isopropylamine, and other aliphatic chain-like amines. Furthermore, both furan-2

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• -dihydro-α-pyrone derivatives, bearing either a distinctive cyclopropane or furan ring and named brevipolides A–O (1–15), have been isolated from the invasive plant Hyptis brevipes Poit. Their fascinating structural features, and the potent biological activities, including cytotoxicity against an array of

• the hydrogen source. Following protection of the alcohol moiety with PMBCl, ether 22 was realized in 93% yield. Afterwards, this species was transformed into the γ-keto α,β-unsaturated aldehyde 23 through an NBS-assisted furan oxidation procedure in moderate yield (65%). The keto functionality was

• cyclization to form the furan ring is then expected to occur concurrently. (−)-Diethyl tartrate (98) was eventually selected as the precursor to construct the unsaturated ester 96 after a double two-carbon homologation. In the reverse order, the synthesis of 13 began with the conversion of diethyl tartrate 98

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• furylmercurials 91 via syn-addition of acetylene, which on carbonylation yielded the furan-containing carbonyl compound 92 (Scheme 30) [83]. It was proposed that initially mercuration of acetylene bonds via mercurinium like ions or π-complex takes place. Then the structure was stabilized through hydrogen bonding

• between alcohol and carbonyl groups (path a) or by hemiketal formation (path b). Thus, the chloride ion attacks from the frontside, producing syn-addition molecules that, upon dehydration, formed furan rings. Later they had reported similar mercuration of arylacetylenes to synthesize a broad spectrum of

• cyclization of secondary and tertiary l-alkynyl-2,3-epoxyalcohols 131a [94]. This is an example of a Hg(II)-salt-catalyzed rearrangement of 1-alkynyl-2,3-epoxy alcohols to substituted furans. The furan 133a was formed by dehydration of intermediate 132a through the corresponding oxonium cation. When R3 is an

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• brominated naphthalene 153 with PhLi yielded compound 154, which collapsed to naphthotriyne 155 at elevated temperatures. Sequential addition of furan generated the trisadduct 156. Then, dibenz[a,c]anthracene 158 was obtained in good yield (86%) in two steps by hydrogenation of 156 and further dehydration of

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• amiodarone (93, antiarrhythmic activity) (Scheme 32A) [166]. The method consists of a tandem, regioselective Fe(III)-catalyzed C–H halogenation, followed by an Fe or Cu-catalyzed O-arylation to access the benzo[b]furan derivatives in high yields. Several natural products and pharmacologically active targets

• bearing the furan ring were synthesized in moderate to good yields. Overall, the new protocol presented a broad scope and excellent functional group tolerance, allowing the synthesis of valuable molecules like corsifuran C (94), moracin F (95), and caleprunin B (96) (Scheme 32D). In 2020, Chattopadhyay

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• precursors in vitro [133]. Furan (F, Figure 8) as a reactive nucleobase mimic was well accommodated in a duplex with DNA without decreasing its thermal stability [134]. Upon oxidation of the furan ring, F-modified PNAs reacted preferentially with cytosine and adenine and irreversibly crosslinked with ssDNA

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• arrangement of the isoindigo and DPP fragments relative to each other was demonstrated [96]. Thus, the dihedral angle 179° in a furan polymer determines the conductivity μh/μe = 0.01 cm2⋅V−1⋅s−1/1.6⋅10−3 cm2⋅V−1⋅s−1, while polymers containing thiophene or p-phenylene spacers did not possess conductivity at

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• [10][11][12][13][14]. For example, Nagumo and coworkers have developed a Prins/Friedel–Crafts cyclization of homocinnamyl alcohols with aromatic aldehydes under the action of BF3·Et2O affording 2H-indeno[1,2-b]furan derivatives [15]. Likewise, Hinkle and coworkers reported in 2017 a three-step domino

• diastereoselectivity (cis/trans ratio = 1:99). The preferential formation of the trans-configured products for furan nucleophiles may be due to the fact that the addition of furan is reversible leading to equilibration to the more stable trans product. To test this hypothesis, we monitored the reaction by HPLC (Table

• , the reactions with other 2-(2-vinylphenyl)ethanals 13b–g carrying different substituents on the benzene ring or on the side chain with veratrole and furan as the nucleophiles were investigated. As can be seen from Scheme 7, under comparable conditions, most reactions proceeded smoothly with the

Organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones

• Chandrakanta Parida and
• Subhas Chandra Pan

Beilstein J. Org. Chem. 2021, 17, 1447–1452, doi:10.3762/bjoc.17.100

• available bifunctional thiourea catalyst was employed in the methodology. Reactions of α-nitroketones with unsaturated pyrazolone and with 4-benzylidenepyrrolidine-2,3-dione. Reaction of 4-benzylidenedihydrofuran-2,3-dione (4) with α-nitroketones 2b,c. Reaction conditions: furan 4 (0.1 mmol), α-nitroketone

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system

• Yamato Fujihira,
• Yumeng Liang,
• Makoto Ono,
• Kazuki Hirano,
• Takumi Kagawa and
• Norio Shibata

Beilstein J. Org. Chem. 2021, 17, 431–438, doi:10.3762/bjoc.17.39

• effect on the yield of the reaction of 1g (Table 2, entries 3–6, 58–72%). Next, a range of common oxygen and sulfur-containing compounds such as furan, tetrahydrofuran, 1,4-dioxane, thiophene, benzo[b]thiophene, dibenzo[b,d]thiophene, and diphenylsulfane were also screened. These substances also have

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• (20), in addition to 3-methylbutan-4-olide (21) and 4-methylhex-5-en-4-olide (22), was detected in strain-specific patterns, with almost all of these compounds present in C. marinus; only C. halophilus did not emit lactones. Furans included furan-2-ylmethanol (23), furfural (24), and 2-acetylfuran (25

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• dienes. Moreover, it was found that furan did not react with nitrostyrenes 1. Furthermore, we performed some subsequent transformations of the fluorinated norbornenes prepared to investigate their chemical properties and to demonstrate their utility (Scheme 6). These reactions were carried out to involve

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• studies on biological activity, chemosensors, and fluorescence, were developed via the reaction of furan-2,3-diones or acylpyruvic acids in the presence of carbodiimides with o-aminothiophenols. The target enaminones were formed together with pharmaceutically interesting 2-hydroxy-2H-1,4-benzothiazin-3(4H

• )-ones. A selective synthetic approach to 2-hydroxy-2H-1,4-benzothiazin-3(4H)-ones was developed via the solvent-switchable reaction of furan-2,3-diones with o-aminothiophenol. Preliminary biological assays (antimicrobial, acute toxicity) of the new compounds were carried out. Keywords: acylpyruvic acid

• ; 1,4-benzothiazine; cyclocondensation; diversity-oriented synthesis; furan-2,3-dione; Introduction Enaminones fused to the 1,4-benzoxazine-2-one I or quinoxaline-2(1H)-one II moiety (Figure 1) represent an intensively investigated class of enamines. Undying interest in these compounds is due to the

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• synthesized through the oxidation of lawsone (6), in the presence of sodium persulfate, followed by methylation [25]. The cyclization of binaphthyl 16 was then attempted taking into consideration the photolytic cyclization of binaphthyls to form pentacyclic furan derivatives [8][18][22]. However, the

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

• ion-pair interaction. For example, the replacement of the pyrrole core to pyridine in 8 or to furan results in a much weaker binding because of the repulsion force between the lone pair on the heteroatom and the oxoanion. The superior oxoanion binding of the Schmuck cation makes GCP-based peptides

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• ) in different positions provided good to excellent isolated yields of the corresponding products 3b–g and 3j–o that ranged from 94 to 98% in a stipulated period of time, as specified in Table 5. Further, heteroaromatic aldehydes, such as furan-2-aldehyde (2p) and thiophene-2-aldehyde (2q) produced the

• 3-Br: 2s) underwent the reaction with ethyl acetoacetate (4) and urea (5) to form the corresponding products (7h–j) in good isolated yields that ranged from 93–96% (Table 6, entries 8–10). Heteroaromatic aldehydes, such as furan-2-aldehyde (2p) and thiophene-2-aldehyde (2q) showed a good reactivity

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Valerii V. Tkachev,
• Andrey N. Utenyshev,
• Olga Yu. Karlutova,
• Alexander D. Dubonosov,
• Vladimir A. Bren,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

• fulgides 3Z and 3E are shown in Figure 1 and Figure 2. Fulgide 3Z possesses Z-configuration at the double bond С(4)=С(5). The 3-methoxy-2-benzo[b]thiophene moiety in 3Z is planar and is almost coplanar with the planar furan-2,5-dione fragment (the dihedral angle is equal to 3.9°). The phenyl rings are

• rotated about the C–Ph bonds by respectively 84.9° (Ph(C(15)-C(20)) and 109.0° (Ph(C(21)-C(26)) relative to the furan-2,5-dione plane. The list of lengths and valence angles of 3Z is given in Table S1 (Supporting Information File 1). Fulgide 3E has E-configuration at the double bond С(4)=С(5). The 3

• -methoxy-2-benzo[b]thiophene moiety in 3E is rotated relative to the furan-2,5-dione fragment by an angle of 36.5°. The torsion angle of the phenyl ring Ph(C(15)–C(20)) relative to the furan-2,5-dione plane (41.5°) is almost twice lesser than that in 3Z, whereas the torsion angle of the phenyl ring Ph(C(21