Hypervalent iodine-catalyzed amide and alkene coupling enabled by lithium salt activation

• Akanksha Chhikara,
• Fan Wu,
• Navdeep Kaur,
• Prabagar Baskaran,
• Alex M. Nguyen,
• Zhichang Yin,
• Anthony H. Pham and
• Wei Li

Beilstein J. Org. Chem. 2024, 20, 1405–1411, doi:10.3762/bjoc.20.122

• electrophilicity of the halogen source could be modulated to render different classes of nucleophiles for additions onto olefins in various olefin difunctionalization reactions [48][49][50][51][52]. In particular, we demonstrated that addition of either a Lewis acid or a base could activate amides to couple with

Synthesis of substituted triazole–pyrazole hybrids using triazenylpyrazole precursors

• Simone Gräßle,
• Laura Holzhauer,
• Nicolai Wippert,
• Olaf Fuhr,
• Martin Nieger,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2024, 20, 1396–1404, doi:10.3762/bjoc.20.121

• hybrids. The selective N-functionalization of the triazene-protected pyrazoles was conducted, and the cleavage of triazenylpyrazoles to the corresponding azides was described for the first time with regioisomer 17, whereas regioisomer 18 is acid-insensitive and cannot be converted. The azides were reacted

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

• potentially useful molecules. Keywords: Cannizzaro reaction; crossed-Cannizzaro; desymmetrization; Lewis acid catalyst; natural products; Introduction The synthesis of functionalized molecules with structural complexity has always been a challenge to synthetic chemists. The Cannizzaro reaction, in its

• aldehyde molecules, forming an alcohol and an acid [1][2][3][4]. Since its discovery in 1853, the Cannizzaro reaction has emerged as an important reaction in synthetic organic chemistry with intermolecular, crossed, and intramolecular versions as demonstrated by numerous applications. Notably, the

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

• facilitate important chemical reactions. Thus, we will focus on the reports detailing organic transformations that proceed via visible-light-induced deoxygenative generation of acyl radicals from carboxylic acids and acid anhydrides that have appeared since 2019. Review General mechanism of photoredox

• via C–O bond cleavage Direct C–O bond activation of acids In visible-light photoredox catalysis, simple and affordable carboxylic acids and acid anhydrides can be utilized as good acyl radical sources for the deoxygenation approach. Acyl radicals can be generated through the use of photocatalysts

• iridium photocatalyst [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 leads to excited-state *[Ir(III)], Ered (*[Ir(III)]/[Ir(II)]) = +1.21 V, possessing sufficient energy to oxidize PPh3, forming the triphenylphosphine radical cation. Subsequently, benzoic acid undergoes deprotonation facilitated by a base, producing

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

• for integrins which is critical for several diseases. Keywords: biphenyltetracarboxylic acid; homo-coupling; integrin inhibitor; rhodium catalyst; Ullmann-type reaction; Introduction The Ullmann reaction is a coupling reaction of aryl halides using copper, traditionally using metallic copper-bronze

Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

• Zining Li,
• Sana Jindani,
• Volga Kojasoy,
• Teresa Ortega,
• Erin M. Marshall,
• Khalil A. Abboud,
• Sandra Loesgen,
• Dean J. Tantillo and
• Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

• system and the C2–C3 alkene, are instilled by these terpene synthases. Four types of eunicellane synthases are known (Figure 1B). The first eunicellane synthase identified, Bnd4 from the biosynthesis of benditerpenoic acid in Streptomyces sp. (CL12-4) [5], forms a cis-eunicellane named benditerpetriene

• collected NMR data of 1 in chloroform [5], but when we dissolved 2 in chloroform for NMR, it cyclized into two 6/6/6-tricyclic diterpenes (5 and 6) [7]. We discovered that 2 was much more sensitive to acid than 1 and eventually took advantage of its reactivity to determine its absolute configuration [7

• -epoxide 9, which readily crystallized (Figure 2A and Figures S5–S10, Table S1 in Supporting Information File 1). Similarly, the 6,7-epoxy derivatives of klysimplexin R (3) and microeunicellene (4) were recently synthesized and isolated [11][21]; 3 cyclized to the 6/6/6-scaffold after the addition of acid

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

• reaction between aminofuranes and maleic anhydride can be carried out successfully in vegetable oils and waxes. The reaction was successfully carried out in sunflower seed oil, olive oil, oleic acid and lauryl myristate under mild reaction conditions. A series of epoxyisoindole-7-carboxylic acid and

• + 2] annulation reactions [68][69][70]. This study was the first to evaluate the performances of sunflower seed oil (SSO), olive oil (OO), oleic acid (OA) and lauryl myristate (LM) as green solvents in the well-known intramolecular Diels–Alder furan (IMDAF) reaction between aminofuranes and maleic

• conventional Diels–Alder reactions [95][118][119][120][121][122][123][124]. On the other hand, the initially exo carboxylic acid substituent in the oxanorbornene ring is converted to its endo isomer by epimerization upon heating the cycloadduct in a mixture of pyridine–glacial acetic acid (1:1). In the process

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

• @(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

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

• as an acid additive (2.0 equiv) could influence the formation of 3a/3a’. The use of these acids in the presence of PIDA did not show any significantly altering reaction outcome (Table 1, entries 5 and 6). We then replaced acetonitrile with dichloromethane to completely prevent the formation of 3a/3a

• by stoichiometric use of HTIB. Attempt to perform the reaction using a catalytic amount of 2-iodobenzoic acid (0.2) under similar oxidizing conditions resulted in slightly diminished yield for the desired α-bromoketone (Table 2, entry 2). Notably, the direct use of HTIB as the catalyst, with a

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

• derivatives with an emphasis on tuning solubility and energy levels. Meanwhile, less attention has been devoted to improving the thermal stability of fullerene derivatives. One well-known example is [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which is recognized for its excellent solubility in solution

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

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

• was observed for the yields depending on the substitution pattern. Instead, the individual purity and quality of the dienes played an important role. Reflux of an EtOH solution of 23a in the presence of PTSA (para-toluenesulfonic acid) afforded benzophenone 24a in 50% yield. The reaction of 6a–r with

• and subsequent acid-catalyzed ring-cleavage and Knoevenagel reaction, similar to the formation of products 21 and 22. The products were formed in 54–84% yields. Again, no systematic trend was observed for the yields. Good yields were observed for dienes containing various substituents located at

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

• spectra of 6a, 9a and 12a (left) and 12a, 12c, and 12e (right, λex = 380 nm) in DCM (c = 10−5 M) at 20 °C. Synthesis of 4. Reaction conditions: i: polyphosphoric acid, 150 °C, 2 h; ii: POBr3 (1.1 equiv), 150 °C, 2 h. Synthesis of compounds 6a–h. Reaction conditions: Pd(PPh3)4 (2.5 mol %), CuI (5 mol

• %), acetylene (3.0 equiv), dioxane, NEt3, 100 °C, 6 h; isolated yields. Synthesis of 8. Reaction conditions: i: polyphosphoric acid, 150 °C, 2 h [33]; ii: POBr3 (1.1 equiv), 150 °C, 2 h. Synthesis of compounds 9a–g: Reaction conditions: Pd(PPh3)4 (2.5 mol %), CuI (5 mol %), acetylene (3.0 equiv), dioxane, NEt3

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

• ]. This reaction comprises four main steps: (i) iodide-mediated aryl transfer from boronic acid to selenium dioxide, (ii) reduction of arylseleninic acid to diaryl diselenide, (iii) oxidation of diaryl diselenide to aryl selenenyl iodide with iodine, and (iv) electrophilic substitution of aniline

• derivatives. With this approach, electrophilic substitution can be achieved in ortho and para positions of aniline derivatives by careful selection of the substrates. Kumar et al. used SeO2 and phenylboronic acid to make symmetrical diaryl selenides [34]. In both cases, aryl transfer from the boron to the

• selenious acid containing polyaniline via chemical oxidation of aniline with SeO2 as oxidant [45]. Further, Tanini et al. described that selenium dioxide has potential to oxidize aniline to form nitrobenzene in aqueous medium [46]. These findings irrevocably confirmed that aniline undergoes significant

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

• , aliphatic chain on the acid component and small aliphatic chain on the aldehyde component to increase the antiproliferative activity. Also, benzyl isocyanide was favored over the aliphatic one (Scheme 1A) [16]. Considering the value of amide groups in drug discovery [19], the feasibility of running the

• alkene 2j carboxylic acids were used successfully in this MCR, demonstrating a great reaction scope (Scheme 2 and Figure 2). Remarkably, the best yields were obtained when heterocyclic carboxylic acid components like 1H-pyrrole-3-carboxylic acid (2n), 2-furoic acid (2o) and 5-nitrofuran-2-carboxylic acid

• (2e) were used. The corresponding products 5nb, 5ob and 5ec were achieved in 63, 51 and 49% yields, respectively. 1-Boc-azetidine-3-carboxylic acid (2i) also gave the corresponding product 5ib in 54% yield. Considering the carbonyl component, 1-chloropropan-2-one (3a) was used to access the

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• -doped CMPs. Thus, when trifluoroacetic acid (TFA) was added to a solution of 3a in chloroform, bathochromic shifts in UV spectra were observed, indicating protonation-induced changes in the electronic properties [10]. Because of the weakly acidic nature of pyridinic nitrogen atoms, an excess amount of

• acid was necessary for this effect to be observed with a maximum equivalent of TFA at 2 × 105, and the absorption band at the longest wavelength gradually shifted as shown in Figure 5a. When we added TFA to a solution of a reference compound 6 having inward-focused nitrogen atoms with a maximum

• on the 0.0067 e·Å−3 isosurface for the electron density. Response towards acid treatment with nitrogen-doped CMPs. (a) Absorption spectra of 3a (CHCl3, 2.3 × 10−6 M) in the absence (black) and presence of trifluoroacetic acid (green: 4.3 × 10−2 M, blue: 2.1 × 10−1 M, red: 4.2 × 10−1 M). (b

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• 2 via Baeyer–Villiger oxidation, followed by hydrolysis to yield another crucial aldehyde/acid intermediate 3 [11][15]. Commencing from 3, diverse ring rearrangement reactions can occur, leading to the formation of distinct products. In the AlpJ-catalyzed reaction, compound 3 undergoes ring

• aldehyde–acid intermediate 11. In JadG-catalyzed reactions, compound 11 participated in a reaction with ʟ-isoleucine to yield 6. In contrast, in AlpJ- or Flu17-catalyzed reactions, 11 underwent decarboxylation and an aldol reaction, giving rise to intermediate 12. Subsequent dehydration of 12 led to the

• -morpholino)propanesulfonic acid (MOPS) buffer (pH 7.5), and the cells were disrupted by ultrasonication to obtain the cell extract. Cell debris was removed by centrifugation (14,000g, 15 min). The proteins were purified by Ni-NTA agarose chromatography, desalted, and concentrated by centrifugation (8,000g

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

• , in addition to having antiviral activity, indacrinone (5), which is related to ethacrynic acid and usually stimulates the reversible short-circuit current and the influx of sodium when applied to the epithelial surface of amphibian skin, and donepezil (6), a drug used to treat Alzheimer's disease [7

• pentadienyl cation [1][2][3][4][5][6][7][8][9][10][11][12]. Until the past decade, the conditions used for the Nazarov reaction generally involved the use of a stoichiometric amount of a strong Lewis acid (e.g., BF3, TiCl4, SnCl4, AlCl3) in relation to the divinyl ketone derivative [21][22][23]. However

• , Dhoro and Tius demonstrated that weak acids could also be used as efficient catalysts for the Nazarov reaction [24]. In this context, some research groups developed methodologies that allowed the use of a catalytic amount of Lewis acid. By using more reactive divinyl ketone derivatives, the

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

• ketone led to the linear α-alkylated product, followed by the alkylation of the methylene ketone with the second benzyl alcohol then afforded the dialkylated product. Remarkably, the drug donepezil, a steroid derivative and a fatty acid derivative were synthesized using this procedure (Scheme 29B). In

• hydrogenated the C=C and C=O bonds delivering the desired alkylated alcohol products (Scheme 49). Recently, Maji’s group showed environmentally benign examples of the manganese-catalyzed dehydrogenative coupling of ethylene glycol and primary alcohols producing value-added α-hydroxycarboxylic acid molecules

• [77]. Several alcohols, including long-chain aliphatic alcohols, were coupled with ethylene glycol using manganese-pincer complex Mn4 (0.5 mol %), KOH (5 equiv) in t-BuOH at 140 °C for 8 h under argon. Excitingly, lactic acid synthesized by treating methanol with ethylene glycol provided a very high

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

• congestion to the highly reactive 1,3-carbons on the furan ring. Thus, phthaloyl chloride was reacted with mesitylene or 1,3,5-triethylbenzene to produce the corresponding diketones 21 and 22. Each diketone was in turn reacted with zinc metal in glacial acetic acid [9] to afford the corresponding 1,3

• mL glacial acetic acid. After attaching a reflux condenser, the mixture was heated to reflux for 12 hours with stirring. The hot reaction solution was filtered. To the hot filtrate was added 5 mL of cold water leading to the precipitation of crude product. The crude product was vacuum filtered

• mmol), zinc dust (1.15 g, 17.6 mmol) and 13 mL glacial acetic acid. After attaching a reflux condenser, the mixture was heated to reflux for 12 hours with stirring. The hot reaction solution was filtered. To the hot filtrate was added 5 mL of cold water leading to precipitation of crude product. The

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

• -neutral phosphinamide and a negatively charged phosphinic acid derivative had excellent stability in water at pH 7.4, but only the charge-neutral compound inhibited human CDA, similar to previously described 2'-deoxyzebularine (Ki = 8.0 ± 1.9 and 10.7 ± 0.5 µM, respectively). However, under basic

• conditions, the charge-neutral phosphinamide was unstable, which prevented the incorporation into DNA using conventional DNA chemistry. In contrast, the negatively charged phosphinic acid derivative was incorporated into DNA instead of the target 2'-deoxycytidine using an automated DNA synthesiser, but no

• /Et3N, followed by silica gel column chromatography, led to the triethylammonium salt of 2-N-Boc-aminoethylphosphinic acid 5 in 50 % yield. Alkylation of acid 5 with methyl chloroacetate in the presence of TMSCl and Et3N took five days at room temperature, and compound 6 as triethylammonium salt was

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

• due to the presence of both bromine and bromide in acid media [43]. Besides, an increased amount of peroxide did not show any noticeable benefits in selectivity toward 3a, but it led to increased formation of over-halogenated products (Table S1, entries 4 and 5 in Supporting Information File 1). The

• decreasing acidity throughout the reaction progress. Since acidity was claimed to have a crucial role [63][64], we contemplated the addition of a small amount of sulphuric acid (Table 2, entry 4). This adjustment led to a significant enhancement towards 3b, resulting in a respectable 57 mol % selectivity

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

• 12 under standard boiling acetic acid conditions, as reported in Scheme 1. The crude product could be collected via vacuum filtration, followed by additional purification via recrystallization from boiling DMF to afford golden crystals of 4a in moderate yields. In order to access 5a and 6a, a

• modified procedure from the literature was implemented [28]. To synthesize 6a, the condensation was performed with 9,10-phenanthrenequinone, building block 12 in the presence of glacial CH3COOH, trifluoracetic acid, and 1,4-dioxane at reflux. Then, recrystallization from DMF and sublimation under ambient

• –elimination pathway will dominate over hydrolysis. This preference was crucial to prevent the formation of undesired carboxylic acid products [28][30][31]. These results also align with the observations previously reported by Takeda and co-workers [24]. The reaction was carried out using a large excess (10

Novel analogues of a nonnucleoside SARS-CoV-2 RdRp inhibitor as potential antivirotics

• Luca Julianna Tóth,
• Kateřina Krejčová,
• Milan Dejmek,
• Eva Žilecká,
• Blanka Klepetářová,
• Lenka Poštová Slavětínská,
• Evžen Bouřa and
• Radim Nencka

Beilstein J. Org. Chem. 2024, 20, 1029–1036, doi:10.3762/bjoc.20.91

• ], and thus avoiding the use of base, leading to the desired intermediate 14 in good yield. Compound 14 was then coupled with ʟ-tyrosine methyl ester followed by deprotection of the amino acid carboxyl group by LiOH⋅H2O. As in the previous base-mediated saponification, here we also received a product of

• synthetic strategy leading to pyridones bearing different aryl substituents is described in Scheme 2. During the Suzuki–Miyaura cross-coupling reaction, which introduced the substituents in the C-5 position, the methyl ester protection of the amino acid moiety was also cleaved, leading directly to the final

• designed based on the work reported by Potts et al. [29] and is described in Scheme 3. The 2-bromo-2-phenylacetyl chloride, necessary for the first step of the synthesis, was prepared from readily available phenylacetic acid [30][31]. The reaction with the 5-membered heterocycles 21 and 26, respectively

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• wide range of substituents on (hetero)aryl iodine(III) compounds, including electron-rich, electron-poor, sterically congested, and acid-labile groups, as well as a broad range of aliphatic and aromatic carboxylic acids for the synthesis of diverse aryl(TMP)iodonium(III) carboxylates in high yields

• reported [18][19] (Scheme 1). The importance of the trimethoxyphenyl (TMP) group as an auxiliary (dummy) ligand on the iodonium salt has prompted researchers to synthesize aryl(TMP)iodonium(III) trifluoroacetates via oxidation of iodoarene with m-chloroperbenzoic acid (mCPBA) in the presence of

• trifluoroacetic acid, followed by coupling with 1,3,5-trimethoxybenzene [18] (Scheme 1A). This process demonstrated tolerance for a wide range of electron-rich and electron-deficient (hetero)aryl iodine(III) compounds. Wirth and colleagues reported the flow synthesis of diaryliodonium(III) trifluoroacetates using

A Diels–Alder probe for discovery of natural products containing furan moieties

• Alyssa S. Eggly,
• Namuunzul Otgontseren,
• Carson B. Roberts,
• Amir Y. Alwali,
• Haylie E. Hennigan and
• Elizabeth I. Parkinson

Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88

• been five natural MMFs isolated and characterized, with all of the MMFs being isolated from Streptomyces coelicolor W75 (Figure 1B). These compounds are 2,3,4-trisubstituted furans, and all five contain a carboxylic acid at the three position and a hydroxymethyl group at the four position. They differ

• the probe was synthesized in good yields, the optimization of the Diels–Alder reaction was undertaken. The Diels–Alder reaction (Figure 3A) was optimized utilizing 3-furoic acid (14) as it fits the requirement of having an electron-withdrawing group in the three position and was an inexpensive

• the carboxylic acid in the three position, the phenyl group is most likely too electron-donating, as well as potentially being too sterically bulky. Finally, pyrrole 21 was tested and ultimately resulted in an inconclusive amount of conversion. Compound 21 does not ionize well on our LC–MS and thus we