Correction: Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2024, 20, 170–172, doi:10.3762/bjoc.20.16

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• challenging targets for total synthesis, however, their biological properties render them highly valuable compounds. The authors utilized a Mn(OAc)3-mediated oxidative cyclization strategy, which begins with the introduction of the fundamental stereochemical information through an asymmetric tandem conjugate

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• exo face of 30b, oxidative cyclization can afford the ruthenacycle 101. Unlike previous works studying Ru-catalyzed cyclizations involving bicyclic alkenes and alkynes [56][57][58][59], the reaction preferentially undergoes β-hydride elimination to generate 102 rather than reductive elimination which

• the 1,6-enyne 194a producing 196 which undergoes an oxidative cyclization leading to 197. Subsequent β-hydride elimination forms 198 which side-on coordinates with azabenzonorbornadiene 30c forming 199. Migratory insertion of the olefin followed by reductive elimination of the hydride affords the

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• underwent undesired ring openings. Treating 12 with BocNH2 resulted in the formation of protected guanidine 15 in 80% yield (Scheme 2c), which would not be possible to obtain via an oxidative cyclization of the corresponding iodine(I) species due to a carbamate cleavage with acid. The other dicationic salts

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• Friedel–Crafts alkylation followed by an anodic oxidative cyclization yielded a defined set of cyclic iodonium salts in a highly substrate-dependent yield. Keywords: electrochemistry; flow chemistry; hypervalent compounds; iodine; oxidation; Introduction Hypervalent iodine compounds (HVI) are well

• , we improved the formation of iodoarenes through a Brønsted acid-mediated Friedel–Crafts reaction followed by an oxidative cyclization to form the desired CDIS 1 (Scheme 1A). This one-pot approach is based on ortho-iodinated benzyl alcohols as starting materials. It allows access to a variety of

• . Conclusion In summary, we have developed the first multi-step continuous-flow procedure for the generation of cyclic six-membered diaryliodonium salts. Starting from easily accessible benzyl acetates we were able to combine a Friedel–Crafts alkylation with a subsequent anodic oxidative cyclization in flow

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• (hydroxylation, hydroperoxidation, halogenation, etc.), cross-dehydrogenative coupling and oxidative cyclization, alcohol oxidation, and the oxidation of other functional groups. Compared to other types of organocatalysis (type I and type II in Scheme 1) reversible bonding and non-covalent interactions of redox

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• ketones and thiourea via an oxidative cyclization initiated by a radical process and a following condensation reaction (Scheme 1c) [29]. Although these methods are practical, most of these strategies require stoichiometric or excess amounts of halogenating reagents or oxidants, which are toxic, hazardous

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

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• . Keywords: antifungal activity; nucleophilic substitution; oxidative cyclization; [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines; Introduction Azolo-annulated azines can be regarded as purine isosteres and are of great interest for modern medicinal chemistry as potential biologically active compounds. In

• cyclization of products 2a–i (Scheme 2). It has been shown that the oxidative cyclization of 1,2,4,5-tetrazines 2a–i into triazolo[1,5-b][1,2,4,5]tetrazines 3a–i takes place by action of (diacetoxyiodo)benzene on heating in trifluoroethanol. The target products were obtained in 10–86% yield. According to TLC

• carried out for the first time. The synthetic approach to new triazolotetrazines involves the preparation of 3,6-disubstituted 1,2,4,5-tetrazines 2a–i bearing the amidine moiety through nucleophilic substitution of the 3,5-dimethylpyrazol fragment in easily available compound 1, followed by oxidative

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

• Echeverria demonstrated a mechanistically distinct protocol for the synthesis of 1,3-dienes 36 (Scheme 7) [72]. Compared to previous Fe-catalyzed carbomagnesiation reactions (Scheme 6) where carbometallation occurs in a concerted syn-manner this protocol, instead, is initiated by the oxidative cyclization of

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• of natural product-like compound libraries. Keywords: [bis(trifluoroacetoxy)iodo]benzene PIFA; nitrogen heterocycles; oxidative cyclization; pyrrolo[1,2-a]quinazolines; Introduction An important design concept in current drug discovery includes structural modifications of naturally occurring

• formation at the two competing nucleophilic centers. Results and Discussion In this work, we propose a regioselective approach to the synthesis of 2,3-dihydropyrroloquinazolin-5(1H)-ones 6 functionalized with a hydroxymethyl group by oxidative cyclization of hereto unknown 2-(buten-3-yl)quinazolin-4(3H

• (0.30) and deoxyvasicinone (−0.01). Therefore, the products obtained in this work indeed fit into the natural product-like chemical space. Conclusion A novel PIFA-initiated oxidative cyclization of 2-(but-3-en-1-yl)quinazolin-4(3H)-ones into 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• contrast, only very few reports deal with the oxidative cyclization of nitrogen-containing biaryl intermediates. Ravi Kumar and Satyanarayana mentioned two successful control reactions using 2-phenylbenzylamine and 2-iminomethylbiphenyl with 5 mol % Pd(OAc)2 and 2 equivalents Ag2O in acetic acid at 140 °C

• nitrogen-containing investigated precursors only primary and secondary benzylamines (see 2a and 2b), giving fluorenone (3) in yields of 62% and 60%, respectively, are suitable functional groups for the TBHP-mediated oxidative cyclization to give fluorenones. These yields are comparable to those previously

• published for fluorenone syntheses starting from other functionalized biphenyls with a key oxidative cyclization step. Starting from biphenyl-2-carbaldehyde (2l), Shi and Glorius [34] reported a fluorenone yield of 68%, utilizing potassium persulfate/tetraethylammonium bromide, the Singh group [35] reported

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

• 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

• biological sciences. Recently, great attention has been paid to synthesize organic azido compounds via various transformations. In 2020, we reported an efficient method for the synthesis of fully substituted azidopyrroles 41 via Cu- and Mn-co-mediated aerobic oxidative cyclization/azidation reaction of 2

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

• 138. Then, an oxidative cyclization of 138 in the presence of FeCl3 afforded dibenzo[a,c]anthracenes 139a and 139b in moderate yields (58–68%). On the other hand, they obtained dibenzo[a,c]anthracenes 139c–e in low to moderate yields (15–54%) when they used DDQ/MeSO3H instead of FeCl3 [66]. In a study

• . AuCl-catalyzed double cyclization of diiodoethynylterphenyl compounds. Iodonium-induced electrophilic cyclization of terphenyl derivatives. Oxidative photocyclization of 1,3-distyrylbenzene derivatives. Oxidative cyclization of 2,3-diphenylnaphthalenes. Suzuki-Miyaura/isomerization/ring closing

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• high diastereoselectivity to the Si face of the iminic carbon. After that, the combination of Pd(TFA)2, lithium acetate and DMSO as solvent led to optimal results in the oxidative cyclization process to produce pyrrolidines 73 as a single diastereoisomer, with relative cis-configuration (Scheme 22

• Grignard reagents to chiral aldimine (RS)-74, and an intramolecular oxidative cyclization of aminoalcohols derivatives 76, are key steps of this approach. Both diastereoisomers of aldimines 74 (RS and SS) were prepared from ᴅ-malic acid and the corresponding enantiomer of tert-butanesulfinamide

• , indicating a mismatch between the chiral auxiliary and the stereocenter in this substrate. Concerning the oxidative cyclization reaction, pyridinium dichromate (PDC) provided low yields of expected lactam 77. Many oxidants were checked for this transformation to take place, and the Sarett reagent [CrO3·(C5H5

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• the last decade, when numerous selective reactions of oxidative cyclization, functionalization, and coupling mediated by iminoxyl radicals were discovered. This review is focused on the synthetic methods based on iminoxyl radicals developed in the last ten years and also contains some selected data on

• reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage. Keywords: iminoxyl radicals; isoxazolines; oxidative cyclization; oxime radicals; oximes; Introduction Free radicals in which an unpaired

• intramolecular reactions of oxidative cyclization. Examples of intermolecular reactions of oxime radicals, a brief description of their structure, stability, and spectral properties are also given. The chemistry of iminoxyl radicals (including their generation, structure, EPR spectroscopy, and reactions) was

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• alkyl and alkoxy substituents at the 3, 6, 13, and 16-positions was achieved based on the ruthenium-catalyzed coupling reactions of anthraquinone derivatives with arylboronates via C–H and C–O bond cleavage. The reaction sequence involving the arylation, carbonyl methylenation, and oxidative cyclization

• tetrabenzo[a,d,j,m]coronene product indicated its self-assembling behavior in CDCl3. Keywords: C–H arylation; C–O arylation; oxidative cyclization; polycyclic aromatic hydrocarbons; ruthenium catalyst; Introduction Polycyclic aromatic hydrocarbons (PAHs) and their derivatives have attracted much attention

• -substituted arylboronate may be converted to 3,6,13,16-tetrasubstituted tetrabenzo[a,d,j,m]coronenes via carbonyl methylenation and oxidative cyclization, the two-step sequential C–O and C–H arylation of 1,4-dimethoxyanthraquinone followed by subsequent methylenation/cyclization would provide tetrabenzo[a,d,j

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• ) side view). UV–vis absorption (solid lines) and fluorescence (dashed lines) spectra of compounds 8a–c. Syntheses of PAH-fused phospholes featuring a 7-hydroxybenzo[b]phosphole as a key intermediate. Synthesis of phosphole-fused ortho-teraryl compounds 7. Oxidative cyclization of phosphole-fused ortho

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• mechanism. One year later, 2013, Collins and co-workers extended this concept to the synthesis of carbazole derivatives under continuous flow conditions (Scheme 30) [44]. Using, the [Cu(I)(dmp)(xantphos)]BF4 catalyst, the oxidative cyclization of various triarylamines was carried out in the presence of I2

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• unsymmetrically substituted pyridines 3a–c in high yields. We then examined the oxidative cyclization of these compounds under the standard conditions adopting Pd(TFA)2 (30 mol %, TFA = trifluoroacetate) and AgOAc (3.0 equiv) as catalyst and oxidant, respectively, in pivalic acid as solvent (Scheme 3). Since the

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• ring closure reaction using N-alkynyl-2-alkylselanylimidazoles and I2 (Scheme 1, reaction 2) [7]. Moreover, Punniyamurthy et al. reported the synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles using an oxidative cyclization by reacting 1,3-diarylselenourea with (diacetoxyiodo)benzene (Scheme 1

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• oxidation states (Cu(0), Cu(I), Cu(II), and Cu(III)). Copper has been known for a long time to act as a catalyst for cross-coupling reactions (Ullmann–Goldberg reaction), cyanation of aryl halides (Rosenmund–von Braun reaction), Hurtley reaction and intermolecular oxidative cyclization of haloalkynes [41

• process oxygen (air) acts as oxidant which resulted in the oxidation of Cu(II) to Cu(III) and Cu(I) back to Cu(II) (Scheme 28). A copper-catalyzed oxidative cyclization approach has been used for the synthesis of formyl-substituted imidazo[1,2-a]pyridines 89. The remarkable feature of this method was the

• HOAc (acetic acid). Where HOAc was suitable for the formation of the Michael adduct and enhanced the electrophilicity of copper while Cl2CHCHCl2 helped in oxidative cyclization. However, the use of HOAc was not good for –COOMe and –CN substituted 2-AP as it

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• one method for the formation of a [1,2,4]triazolo[4,3-a]pyridine ring with participation of an acetylene triple bond; an oxidative cyclization during the reaction of terminal phenylacetylenes with 2-hydrazinylpyridines [14]. However, data on phosphorus-containing triazolopyridines are scarce, although

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-a]pyridines

• Olga A. Storozhenko,
• Alexey A. Festa,
• Delphine R. Bella Ndoutoume,
• Alexander V. Aksenov,
• Alexey V. Varlamov and
• Leonid G. Voskressensky

Beilstein J. Org. Chem. 2018, 14, 3078–3087, doi:10.3762/bjoc.14.287

• proceeds through a domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction sequence. Keywords: 2-aminochromene; domino reaction; imidazo[1,2-a]pyridine; 2-iminochromene; Michael addition; multicomponent reaction; oxidation; pyridine amination; Introduction Domino reactions are well

• conclusion, we have developed a practical route towards substituted chromenoimidazopyridines through a sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction, employing cheap and abundant oxidants. The discovered process works in a broad substrate scope with