Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• the amount of CuSO4, as well as the timing of its addition to the cyclization reaction, hoping to limit the oxidation side reaction. This was indeed beneficial, as the B3/B4 ratio changed from 50:50 to >95% formation of B3. Interestingly, all attempts at rerunning the reaction that produced B2 under

Unraveling the role of prenyl side-chain interactions in stabilizing the secondary carbocation in the biosynthesis of variexenol B

• Moe Nakano,
• Rintaro Gemma and
• Hajime Sato

Beilstein J. Org. Chem. 2023, 19, 1503–1510, doi:10.3762/bjoc.19.107

• in the cyclization reaction. The role of these prenyl side chains has been partially investigated, but remains elusive in the cyclization cascade. In this study, we focus on variexenol B that is synthesized from iso-GGPP, as recently reported by Dickschat and co-workers, and investigate the

• cyclization reaction from the exomethylene group proceeds without a barrier, similar to the previous pathway. Regarding the orientation of the prenyl side chain, two pathways can be considered depending on whether the hydrogen at C14 is pointing; α-hydrogen (path a) or β-hydrogen (path b). Both pathways

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

• construction of 4-chalcogenylated pyrazoles 57 and 59 was carried out starting from α,β-alkynic hydrazones 55 (Scheme 24) [60]. In the procedure, α,β-alkynic hydrazones were subjected to S- or Se-electrophiles 56 and cyclization reaction. Additionally, NCS and ArSH produced the S-electrophile for the

• cyclization reaction with arylpropynal hydrazones. Also, the reaction of 1-(1,3-diphenylprop-2-yn-1-ylidene)-2-phenylhydrazine 58 as the substrate with N-sulfenylsuccinimides 1 afforded fully substituted pyrazoles 59 in up to 98% yield. In 2021, a solvent-controllable approach for the construction of 3

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• showed that the carbonyl group of the dimedone does not take part in the further cyclization reaction, while the carbonyl group of the benzoyl group participated in the annulation reaction to give the pyrrolidyl ring. This result clearly indicated that the adducts of 3-phenacylideneoxindoles showed

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• intramolecularly with the C4-pendant prenyl side-chain previously oxidized [76]. Closure of the photoredox catalytic cycle would then involve SET reduction, and protonation would deliver the desired carbocyclic ring (Figure 1c). If this cyclization reaction could be realized in either way, it would shorten the

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• cyclization reaction using 4e by 1H NMR. Versatile reactivities of cyclopropanes 1a. Preparative methods for cyclopropanedicarboxylates 1a. Bromination of ethyl acetoacetate (3c) and reaction with nitrostyrene 2a. Reaction of 4b with (diacetoxyiodo)benzene (top); structural determination of product 9 (bottom

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

• . systematically modified atropisomeric C1-symmetric stack ligands to identify suitable catalytic systems for a highly enantioselective synthesis of organoboranes (Scheme 42) [83]. Their best attempt to realize a tandem borylation/aldol cyclization reaction resulted in 72% yield, 90% ee, and a diastereomeric ratio

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

• scaffolds 147 through a domino ARO reaction followed by cyclization reaction of oxabicyclic alkenes 30 with sodium cyanate (146) (Scheme 26) [72]. This reaction proceeded smoothly with electron-rich oxabenzonorbornadiene derivatives; however, electron-poor oxabenzonorbornadiene derivatives resulted in

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• formation occurs during the other reacting basin’s evolution. During the process, N12 loses its lone pair which is involved in the C5–N12 bond formation, and after the cyclization reaction, in a second stage, the lone pair is recovered after the proton (H13) is abstracted by the phosphoric acid. As expected

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

• or more heteroatoms in the dienone core have the potential to provide efficient access to a variety of heterocyclic scaffolds. Among such variants, the aza-Nazarov reaction appears as a highly suitable cyclization reaction that presents opportunities for the construction of a diverse array of five

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• investigations revealed that this cyclization reaction proceeds via a cascade radical pathway. We expect these results to encourage the further development of NaI/PPh3-catalyzed and related synthetic methods. Representative natural products and biologically active molecules containing an oxindole moiety [7][8][9

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• ] and provides insights into the biosynthesis pathways of these peptides [14]. However, the biosynthetic gene clusters of compounds 1–4 remain unidentified. Therefore, the least sterically hindered amine, namely the amino group of glycine, was selected as a nucleophile of the cyclization reaction in

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• tested (see Supporting Information File 1). Next, compounds 17a and 17b were brominated in the α-position using Br2 under acidic conditions. Finally, cyclization reaction with 2-aminothiophenol (8a) in dry diethyl ether at 0 °C gave benzo-1,4-thiazines 19a and 19b in good yield. Interestingly, the

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• fumigatonoid A (path 3). The C13 peroxide intermediate 5 is generated from intermediate 2, which is subsequently epoxidated at C2'–C3' to form intermediate 6. The following cyclization reaction from the peroxide generates fumigatonoid A (path 4). The epoxide formation reaction occurs first at C2'–C3' of

Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• containing two acceptor (maleimide and pyridine) and one donor (secondary amine) moieties in 72% yield (Scheme 1). Due to the electron-withdrawing effect of the bromo substituent at position 5 of the pyridine ring, the cyclization reaction did not occur. The structure of product 4a was confirmed by 1H and

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• ]. Conventional synthetic methods for piperidine derivatives include nucleophilic substitution (route (1) in Scheme 1), reductive amination (route (2)), intramolecular cyclization of amines and alkenes (route (3)), the Diels–Alder reaction and subsequent reduction (route (4)), and the radical cyclization reaction

• ); therefore, the competition between the reduction of 2c and that of the imine 1 may have caused the low yield of 3a. A large amount (50%) of unreacted 1 was recovered in this case. Therefore, it can be stated that Br is appropriate as the terminal halogen of the dihaloalkane in this cyclization reaction. A

• the desired cyclization reaction via the reduction of 1. Conclusion We have demonstrated a facile, green, and efficient method for the synthesis of heterocyclic amines by electroreductive cyclization using a flow microreactor. This method not only allows the synthesis of pyrrolidine and piperidine

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• , isolated from oils distilled from citronella plants, which is very effective as a repellent and antifungal. In the presence of Brønsted or Lewis acids (S)-citronellal undergoes an intramolecular carbonyl–ene cyclization reaction forming two new stereogenic centers, which turns out into four possible

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

• can also be used as an oxidant for the oxidation of benzamidine derivatives 2b,c in acetonitrile under microwave irradiation. Along with the cyclization reaction, bromination of the pyrazole ring proved to occur at position C(4) to give the products 3j,k, as evidenced by disappearance of the

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• through a gram-scale synthesis, one-pot three-component reactions and further transformation experiments of the products. Keywords: asymmetric catalysis; cyclization reaction; Michael addition; one-pot three-component reaction; spirobarbiturates; Introduction Indane scaffolds exist in various

• strategy to construct a series of spirobarbiturates derived from indanone. Combining current researches of these two compounds, we report the first organocatalytic asymmetric Michael addition/cyclization reaction between barbituric acid-derived olefins and indanones (Scheme 1b). Under the action of the

• . Results and Discussion To verify the feasibility of the reaction, the domino Michael addition/cyclization reaction of 2-isothiocyanato-1-indanone (1a) and barbiturate-based olefin 2a was used as a model reaction, which was carried out in dichloromethane (DCM) with 5 mol % quinine-derived squaramide C1 at

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

• )quinolines 1a–f was synthesized via an intramolecular cyclization reaction, in which trifluoromethyl-substituted enamino ketones reacted with concentrated sulfuric acid at adequate temperature (120 °C) and time (10 hours) to furnish the desired compounds, following the method already described in the

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• the total syntheses of 10 alkaloids in racemic form. Major advantages are a) using ω-methoxystyrenes as convenient alternatives to arylacetaldehydes, and b) using the ethoxycarbonyl residue for both activating the arylethylamine precursors for the cyclization reaction, and, as a significant extension

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

• position indicates an inversely proportional relation between the strength of the −I effect exerted by substituents and the efficiency of the cyclization. Reaction of amine 15m (see Scheme 5) did not give the corresponding fluorenone, instead phenanthridine 10m was isolated in 36% yield. Most likely

• unsuccessful, fluorenone (3) was not formed under either of these conditions, suggesting the involvement of radicals in the cyclization reaction rather than an SEAr mechanism as proposed in Scheme 3. A more detailed investigation might be required to fully understand the mechanism of this oxidative benzylamine

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• well as tert-butyl as precursors for the silica gel-mediated cyclization reaction to form pyrrolizine products. The bromomethyl ketones required for the initial sulfide contraction were either purchased from commercial suppliers or prepared from the corresponding methyl ketones by reported procedures

• which characteristic 1H or 13C NMR spectroscopic signals could be observed, and suitable HRMS values could be measured; see Supporting Information File 1) to the optimized cyclization reaction conditions, since the contaminants did not inhibit pyrrolizine formation. Chromatographic purification of

Synthesis of new substituted 7,12-dihydro-6,12-methanodibenzo[c,f]azocine-5-carboxylic acids containing a tetracyclic tetrahydroisoquinoline core structure

• Agnieszka Grajewska,
• Maria Chrzanowska and
• Wiktoria Adamska

Beilstein J. Org. Chem. 2021, 17, 2511–2519, doi:10.3762/bjoc.17.168

• tetrahydroisoquinoline derivatives, 7,12-dihydro-6,12-methanodibenzo[c,f]-azocine-5-carboxylic acids by three component Petasis reaction with the use of aminoacetaldehyde acetals bearing substituted benzyl groups as the amine components followed by Pomeranz–Fritsch double cyclization reaction. By applying this method

• the intramolecular Friedel–Crafts double cyclization reaction and N,N-dibenzylaminoacetaldehyde dialkyl acetals [12][14][15][16] in the Pomeranz–Fritsch-type double cyclization reaction. There is also one example of employing p-quinol acetates as substrates for the synthesis of these compounds [17

• cyclization reaction was easily performed by treatment of 6a with 20% HCl for 24 h to give dihydromethanodibenzoazocine-5-carboxylic acid (7a, Scheme 5) in 72% yield by extraction of the neutralized reaction mixture. Compound 7a was obtained in two simple steps from 3a with an overall yield of 67%. Then the

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