Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• have been employed in benzocyclization and arylocyclization reactions, enabling intramolecular cyclization by forming aromatic or heterocyclic rings as a part of cyclic structures [8]. In these reactions, the dual activation of a C–I bond and vicinal C–H bonds/functional groups features a distinct

• diaryliodonium salts in a cascade cyclization, the cyclization features a copper-catalyzed activation strategy involving the cleavage of the C–I bond and esterification. The resulting cascade of selective arylation/intramolecular cyclization facilitated the synthesis of 3,4-benzocoumarin derivatives. The

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• can be found in bioactive molecules and have been tested in structure–activity relationship studies (Scheme 1A) [8][9][10]. Moreover, transformations have been developed to exploit the two functional groups simultaneously, for example through their intramolecular cyclization to form pyrroles in the

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• alcohols, followed by base-promoted cyclization to afford the target spirocyclic compounds in good to high yields. Keywords: diazoarylidene succinimides; intramolecular cyclization; rhodium(II) carbene O–H insertion; spirocycles; Introduction Spirocyclic motifs have emerged as auspicious frameworks for

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• Tsvelikhovsky introduced an efficient synthetic strategy to construct diverse dibenzodiazepinones through a sequential methodology consisting of a B–H coupling between o-carbonylanilines and 1,2-dihaloarene derivatives providing access to key precursors that undergo a tandem amination–intramolecular cyclization

• carbonylative intramolecular cyclization of the intermediate 3a using different catalytic systems. To elucidate the role of the palladium catalyst in this process, we carried out the initial attempt under metal free-conditions using molybdenum hexacarbonyl (Mo(CO)6) as CO surrogate, in the presence of Et3N in

• . The reactivity of Co2CO8 as CO surrogate was also explored, in this case the reaction afforded the DBDAP product 4a in 55% yield (entry 6, Table 3). Molybdenum hexacarbonyl (Mo(CO)6), was shown to be a powerful CO surrogate in this carbonylative intramolecular cyclization. The efficacy of Mo(CO)6 is

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• , Umemoto’s reagent undergoes a homolysis process to generate the trifluoromethyl radical species. The trifluoromethyl radical is trapped by the terminal alkene and forms a relayed radical intermediate 6, which is intercepted by the indole ring realizing an intramolecular cyclization (6-exo-trig). The newly

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• aromatic nitro derivatives 3 and 6 proceeds through the corresponding hydroxylamines, capable of intramolecular cyclization to products 4 or 7. Fortunately, under Zn/AcOH reductive conditions this was resolved by extending the duration of the reaction to 18–24 h, providing enough time for compounds 4/7 to

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• Nef reaction in MeNO2 under acidic conditions. In the meantime, 1 was activated by AlCl3 to form sulfenium cation I, which induced an intramolecular cyclization of 60 to produce pyrroline 62. In MeCN solvent, 3-thiolated pyrroline 62 was stable and could be isolated, but in MeNO2, in the presence of

• first thiolation and intramolecular cyclization of propargyl azides the removal of N2 and a proton. Subsequently, monothiolated perroles were subjected to the second thiolation process to prepare 3,4-bisthiolated pyrroles. Cyclic voltammetry and DFT calculations revealed that the 3,4-bisthiolated

• formation of three-membered cyclic sulfonium ion II followed by ring-opening of sulfonium ion and intramolecular cyclization. The use of a Lewis base/Brønsted acid catalysis system for the sulfenylation of aromatic substrates 4 was reported by Gustafson et al. (Scheme 55) [87]. In the method, catalyst P

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• calculations, and to study their intramolecular cyclization in triflic acid into the synthetically and medicinally relevant (see recent reviews [12][13][14][15][16][17][18]) indan-1-ones. Results and Discussion The synthesis of 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones (CCl3-hydroxy ketones) 1a–o was

• electron-donating substituents in the aromatic ring gave oligomeric materials. Presumably, in these cases, after dehydration and formation of the corresponding enone 2, the latter underwent subsequent cationic oligomerization. Next we studied the intramolecular cyclization of compounds 1 and 2 in TfOH. It

• C1 (0.60 e). This carbon atom gives 14.9% contribution to the LUMO. Contrary to that, the carbon C3 bears no positive charge (−0.13 e) and contributes 12.1% to the LUMO. The intramolecular cyclization of cation Ba takes place between the atom C3 and the ortho-carbons of the phenyl ring. Thus

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• beginning of the reaction, copper(II) 2,3-diamino-5,10,15,20-tetraarylporphyrins 1 react with 2-hydroxynaphthalene-1,4-dione (2) in the presence of trichloroacetic acid to form an imine intermediate which on intramolecular cyclization affords a key benzo[f]quinoxalinoporphyrin intermediate 17. Further, a

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• guanidine C. Finally, the intramolecular cyclization of the guanidine moiety and the carbonyl group leads to the target pyrimidine 9. After the general synthetic method for pyrimidines containing the allomaltol fragment had been established, the photochemical behavior of the obtained compounds 9 was

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• deliver N-arylsulfonylimines under mild reaction conditions is highly desirable. Previously, we reported a tandem oxidative intramolecular cyclization of N-aryl(benzyl)amines, having an internal nucleophile substituted at the ortho-position in the aniline ring, to nitrogen heterocycles using potassium

• persulfate (K2S2O8) as the exclusive reagent [14]. The mechanistic study revealed that an initial oxidation to an iminium ion could be the key intermediate in the intramolecular cyclization step. In sharp contrast, when N-aryl(benzyl)amines that do not have an ortho-substituted nucleophile in aniline ring

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• ) [32]. The third group of approaches to the PBTA scaffold includes only one example, the intramolecular radical substitution reaction in 1-(2-bromophenyl)-5-(butylsulfanyl)pyrrolidin-2-one (Scheme 3, entry 13) [8]. The fourth group of approaches to the PBTA scaffold is the intramolecular cyclization of

• approaches from Scheme 4). Then, intermediate A underwent an intramolecular cyclization by the attack of the SH group on the C5 atom of the pyrrole-2,3-dione moiety to afford intermediate B that underwent a 1,3-prototropic shift to give product 3aa. Next, the conditions (Table 1) of the model reaction of

• the cleavage of the S–C bond of the 1,4-benzothiazine moiety under the action of the nucleophile to form in situ a 1-(2-thiophenyl)pyrrole derivative that undergoes an intramolecular cyclization to give the target pyrrolobenzothiazoles 3, 7, and 12. The developed approach works well with alkanols 2

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

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

• the bicyclic alkene followed by migratory insertion affords intermediate 12 which undergoes β-oxygen elimination to form 13. Rearrangement of 13 via β-hydride elimination and enolization generates a 1-naphthol species which undergoes intramolecular cyclization with the ester to form the final product

Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C

• Karolina Wątroba,
• Małgorzata Pawełczak and
• Marcin Kaźmierczak

Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33

• with nucleophilic deoxyfluorinating reagents often does not lead to the expected products with a fluorine atom in place of the –OH group. They usually undergo rearrangement, and intramolecular cyclization leading to products that are constitutional isomers [15]. The solvolysis reaction of phosphonates

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• order to obtain higher yields in the intramolecular cyclization step, the authors also investigated the use of a strategy based on an SNAr reaction using an electron-deficient aryl halide. Thus, 4-fluoro-3-nitrobenzaldehyde (118) was subjected to the Still–Gennari reaction, to give the corresponding cis

• -olefin 119 which was reduced using DIBAL to lead to the allylic alcohol 120. Subsequent Mitsunobu reaction between the alcohol 120 and carboxylic acid 26 gave the corresponding ester 121 in a 64% yield. However, the intramolecular cyclization step did not lead to the desired compound 122, even when

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• additional functionalization steps the key intermediate 128. This compound constituted the substrate for the Pd-promoted intramolecular cyclization. In this case, an enol triflate was used instead of an alkenyl halide which required the presence of an electron-rich phosphine, a lower temperature (50 °C

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• for the synthesis of isocoumarin scaffolds. Traditional synthetic strategies including 1) intramolecular cyclization of 2-alkenyl benzoic acids or o‑alkynylbenzoates (Scheme 1b, I) [6][7][8][9][10], 2) oxidation of isochromans (Scheme 1b, II) [11][12], or 3) metal-catalyzed cross-coupling/cyclization

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• on the success of the catalytic aza-Nazarov reaction. Keywords: α-methylene-γ-lactam; aza-Nazarov reaction; β-silicon effect; heterocycles; intramolecular cyclization; Introduction The rapid construction of aliphatic heterocycles from acyclic building blocks via cyclization or cycloaddition

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• further oxidized, and thus producing the respective benzylic cation. Intramolecular cyclization in the cationic position under participation of the methyl ester function provided the core for (+)-grandilodine C (191) and (+)-lapidilectine B (192), while allylation of the benzylic position allowed

• basic deprotection of the acetyl and benzoyl groups, followed by intramolecular cyclization and angelate esterification. Also, the differently redox-active DBCOD bearing an angelate functional group enabled the synthesis of kadsuphilin N (234). The synthetic sequence utilizes Fu’s protocol for palladium

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

• of a hydroperoxide (terminal oxidant) on a ketone or imine, respectively, is followed by intramolecular cyclization with O–O bond cleavage and the formation of a strained 3-membered ring, an electrophilic oxygen atom donor for oxidative processes (Scheme 30). It should be noted that in the ketone

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• formation systems, we herein report a rhodium-catalyzed intramolecular reductive aldol-type cyclization and its application for the synthesis of a chiral necic acid lactone. Results and Discussion Rh-catalyzed intramolecular cyclization When applying our previously reported conditions [43], the

• reaction by intramolecular cyclization of 1, and the results are summarized in Table 1. The use of [RhCl(cod)]2 in dichloromethane gave the best result with high diastereoselectivity, and the stereochemistry of the major product 2a was found to be the syn-form with regard to the CH3 (Cα) and OH (Cβ

• - and/or δ-position of 2 help the formation of the intermediate structure which works in favor of the intramolecular cyclization. β-Substituted substrates on α,β-unsaturated ester moiety of 1 also gave the products (2g and 2h) in low yields, but the formation of the 7-membered ring (2f) was not achieved

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• conventional methods; a notable alternative is the cyclodesulfurization, where intramolecular cyclization is combined with desulfurization from thioamide analogs such as thioureas, thiosemicarbazides, and dithiocarbamate salts under mild reaction conditions [10]. These synthesis methods are effective for