Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• aromatic hydrocarbon radicals, which can persist in air-saturated solutions for several days to months, have been synthesized by employing bulky substituents around the spin-localized carbon center [13][14][15]. These stable radicals have paved the way to elucidate the nature of radical species, advancing

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• the field of bioconjugation and materials research. We previously reported a regioselective double addition of organic azides to octadehydrodibenzo[12]annulene derivatives with electron-rich alkyloxy substituents. In order to increase the reaction rate, electron-withdrawing substituents were

• ], and crosslinked polymers [14][15][16][17]. Since crosslinking polymers requires high reaction efficiency under mild conditions, developing such reactions is crucial. We previously reported the regioselective double azide addition to octadehydrodibenzo[12]annulene with hexyloxy substituents (DBA-OHex

• ), which are readily accessible by the oxidative acetylenic coupling of a 1,2-diethynylbenzene derivative (Figure 1) [18]. The chemical stability of DBAs depends on the electronic character of the substituents. Electron-donating alkyloxy groups are known to enhance the stability of DBAs. On the other hand

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• well as electron-withdrawing substituents on the two phenyl rings in compounds 1, such as methyl, methoxy, halogen atoms (F, Cl, Br, I), CF3 and SO2CH3, were well tolerated, and their electronic effects insignificantly impacted the formation of 3. Similarly, N-benzyl-3-oxo-3-phenylpropanamide (3w

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• was released [57] allowing direct comparison of different substituents. On the basis of the calculated Hammett constants, we have selected a model series of 1,3-diketones, bearing heterocyclic substituents with a range of electron-withdrawing ability (Figure 2). For the amine model series, we used

• 0.267/0.305) substituents reacted with primary and secondary alkylamines, requiring prolonged heating and a 1.5 excess of amine (Scheme 4), to give meta-substituted arylamines in reasonable synthetic yields. In the case of 1,3-diketone 1d, the addition of molecular sieves is necessary in order to reduce

• the formation of the enamine side-product. Similar to 1,3-diketone 1b, an extremely low conversion of 1c and 1d was observed in the reaction with aniline. The isoxazol-3-yl or furan-2-yl substituents have calculated Hammett constants below 0.200 (Figure 2), thus based on the above observations, a slow

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• [131][132][133], it is quite likely that alternariol and its derivatives are partly present in the organisms as O-glucosides, acetates, or sulfates [134][135], where these substituents are most generally cleaved during the isolation and work-up processes. These derivatives (glucosides and sulfates) are

• further data did no become accessible to the author. The given name ‘5-hydroxyaltenuene’ is misleading and its utilization is not recommended [269]. Substituted altenuene and diastereomers: A number of altenuene diastereomers with further O-substituents are given in Figure 16. 2-O- and 3-O-acetylaltenuene

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• nitrogen-containing compounds [3][4][5][6][7]. Furthermore, by adjusting the substituents on the nitrogen, reactivity can be controlled and solubility in various solvents can be tuned (Figure 2). However, the use of isocyanide as a C1 resource is somewhat limited compared to that of carbon monoxide [8

• yields. In the case of tert-butyl and benzyl isocyanides, the substituents on the nitrogen of imidoyl radical 2 (R = t-Bu or PhCH2, E = Et2P or Ph2P) were eliminated to give cyanophosphines (R’2P–CN, Scheme 7) [38]. On the other hand, we attempted a photoinduced addition of phosphorus–phosphorus

• substituents on the heteroatom. For this reason, the 1,1-addition is less likely to proceed as with group 16 or 15 heteroatom radicals. In the case of stannyl and silyl radicals, the alkyl group of the isocyanide is eliminated as an alkyl radical from the imidoyl radical intermediate 2 [42]. The formed alkyl

From perfluoroalkyl aryl sulfoxides to ortho thioethers

• Yang Li,
• Guillaume Dagousset,
• Emmanuel Magnier and
• Bruce Pégot

Beilstein J. Org. Chem. 2024, 20, 2108–2113, doi:10.3762/bjoc.20.181

• % using hex-5-enenitrile. Conclusion In summary, fine-tuning of the experimental conditions gave us access to original ortho-cyanoalkylated aryl perfluoroalkylsulfur derivatives. We have also shown that structural diversity is possible by varying the substituents on the aromatic ring, the perfluoroalkyl

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• formate (Scheme 8) [58]. Upon reaction with β-ketoesters, hydrazone 30 is formed, which reacts via intramolecular Knoevenagel condensation to give the corresponding pyrazoles 27. The method tolerates β-ketoesters with alkyl substituents and various ketoamides. In addition, an example could be synthesized

• and elimination to give the corresponding pyrazoles 52 (Scheme 15) [70]. The cross-coupling introduced various aryl substituents at position 4. Furthermore, using 1,4-diiodobenzene as a starting material allows access to bispyrazole derivatives. According to Beller [71], using bisadamantyl-type

• to synthesize 3,4-substituted pyrazoles 57 from iodochromones 55, arylboronic acids 56, and hydrazines (Scheme 16) [72]. During the Suzuki step, electronically and sterically diverse substituents were successfully coupled to chromones. Notably, a single regioisomer is formed when methylhydrazine is

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

• Deepa Nair,
• Abhishek Tiwari,
• Banamali Laha and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177

• methodology (Table 2). At first, various arylidenemalonates 2 were tested with a phenyl analog of curcumin 1. The reaction of 1a with arylidene malonates 2a–c, bearing weakly electron-withdrawing para-substituents, produced the corresponding double Michael adducts 3a–c, respectively, in good to high yields

• curcumins 1 with arylidenemalonate 2 can be explained in terms of the relative stereochemistry of the substituents in the enolate arising from the first Michael addition (Figure 3). Comparison of the two possible transition states TSI and TSII for second Michael addition suggests that a severe 1,3-allylic

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• regardless of the electronic properties of the substituents on the N-phenyl ring. When dissymmetric diaryl ketone-derived substrates were employed, the C–N bond formation occurred selectively on the most electron rich aromatic ring. According to the proposed mechanism, this dehydrogenative cyclization of

• substituents on the aromatic moiety regardless of their electronic properties. However, 4,5-disubstituted 1,2,3-thiadiazoles could not be accessed with this methodology. Mechanistically, control experiments with radical trapping agent such as TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) or 1,1

• ,N-disubstituted hydazones 101 for synthesiszing tetrazoles 103. Sodium azide could be an alternative source of azide, albeit with both slightly lower yields and Faradic efficiency. Remarkably, (hetero)aromatic as well as aliphatic aldehydes proved to be efficient. Various substituents on the N(sp3

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• oxymethine H15, which in turn was correlated with a methylene H214. The pyrrole moiety with the same substituents as 1 was deduced from HMBC correlations. Therefore, compound 2 was determined to have a non-branched alkyl chain with a hydroxy group at C15. Meanwhile, 3 possessed a terminal ethyl group, which

Development of a flow photochemical process for a π-Lewis acidic metal-catalyzed cyclization/radical addition sequence: in situ-generated 2-benzopyrylium as photoredox catalyst and reactive intermediate

• Masahiro Terada,
• Zen Iwasaki,
• Ryohei Yazaki,
• Shigenobu Umemiya and
• Jun Kikuchi

Beilstein J. Org. Chem. 2024, 20, 1973–1980, doi:10.3762/bjoc.20.173

• photochemical sequential transformation. With the optimal flow reaction conditions in hand, we next investigated the scope of substrates 1 by introducing a series of substituents to the terminal phenyl group. The results of the batch reaction system are also shown for comparison in Table 2 (right-hand side) [55

• reactions of aldehydes with a series of substituents introduced to the terminal phenyl group were further investigated (Table 3, entries 4–7). Aldehydes having an electron-donating methyl group and an electron-withdrawing bromo group at the para-position of the phenyl moiety gave products 3o and 3p

Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators

• Siham Asyiqin Shafie,
• Ryo Nozawa,
• Hideaki Takano and
• Hiroshi Shinokubo

Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172

• analysis, which revealed that two alkyl substituents were located on the same side of the molecule (Figure 2a). Compared to the planar structure of 1 (Figure 2b) [2], 2a displays a nonplanar structure due to the sp3 carbon atoms adjacent to the nitrogen atoms. The 1H NMR spectrum of 2a confirmed that the

• . Finally, another isobutyronitrile radical reacts with I at the convex face to form the major product 2a, with two alkyl substituents on the same side of the molecule. The mean-plane deviation (MPD) of I was 0.293 Å, where the mean plane was defined by carbon, nitrogen, and nickel atoms of the norcorrole

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• simple and mild method to selectively generate N1- or N2-substituted indazole analogs when the substituents appear to favor one over the other. Ideally, it would be greatly beneficial if the desired high regioselectivity on N1 or N2 could be achieved when commercially available chemicals, such as

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• spectra are very similar. These results indicate that substituents with different functional groups can be attached to DPP 2 without significant modification of their optical properties. The observed Stokes shifts for dyes 3 and 4 averaged in the range of 60–70 nm. All compounds exhibited high

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• % yield. Additional experiments were then carried out using N-methoxy-2-(prop-1-en-2-yl)benzamide with different substituents R2. Both electron-donating (methyl, alkoxy, dimethylamino) and electron-withdrawing substituents (fluoro, chloro, trifluoromethyl) were well tolerated on the phenyl ring and gave

• , respectively, the substrates could be successfully converted to the products 3b–d and 2f in 52–87% yield with this method. In addition, a good or high yield of 3-methylisoquinolinones 3e–k, with different substituents on the phenyl ring, was also obtained. It is worth noting that when an electron-withdrawing

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• salts. The oxidative behavior of substituted diarylamines is known to be very diverse and strongly influenced by the substituents in the phenyl rings as well as by the type of the oxidant. Diarylamines can serve as precursors for a wide variety of practically useful compounds such as diarylnitroxides

• diphenylamines yielding N,N-diarylbenzidines and N,N-diaryldihydrophenazines were reported in [21]. By varying the reaction conditions and additional substituents in the phenyl rings, a possibility for the selective oxidation of ortho-(2-pyridyl)diphenylamine to the corresponding nitroxide, as well as the

• equivalent nitrogen atoms (aN = 6.56 G) as well as additional triplet splitting provided by hyperfine interaction with a pair of equivalent protons (aH = 1.89 G). In contrast, only traces of this admixture were detected for the diarylamines with electron-withdrawing substituents. This is in line with our

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles

• Ivan Lyutin,
• Vasilisa Krivovicheva,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164

• . It can be observed that the 5-monosubstituted diazo derivatives, and especially those with no substituents in position 5, form the target products in lower, often moderate yields (see products 3i,j,n and 3r,s,t) compared to the 5,5-disubstituted (spirocyclic) analogues. This result may be related to

• the lower stability of the less-substituted β-lactam derivatives under thermolysis conditions. Additional alkyl substituents sterically shield the ring and prevent an unwanted nucleophilic attack leading to product degradation. In reactions with alcohols and mercaptans, the corresponding esters 3k–n,r

2-Heteroarylethylamines in medicinal chemistry: a review of 2-phenethylamine satellite chemical space

• Carlos Nieto,
• Alejandro Manchado,
• Ángel García-González,
• David Díez and
• Narciso M. Garrido

Beilstein J. Org. Chem. 2024, 20, 1880–1893, doi:10.3762/bjoc.20.163

• SAR study was achieved creating N-arylimidazolethylamine counterparts 55–59 (Scheme 9). It was shown, that electron-withdrawing substituents at the pyridine 5-position lowered the antagonistic activity for this small family. Conformationally restricted cyclopropylhistamine analogues were disclosed by

• ). Later, the authors expanded the histaprodifen family by SAR exploration of small substituents in the phenyl rings (compounds 67–78, Scheme 11) [59][60]. While pEC50 values varied very subtle, a histamine relative potency screening revealed a general reduction in potency. Following the same assay

• second generation series, i.e., compounds 91–94 (Scheme 12), featuring simple hydrocarbon substituents was elaborated. This collection showed good activities, demonstrating the tolerance of introducing bulky moieties at position C2 or N1 of the imidazole ring. Researchers also described positive membrane

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• aliphatic and aromatic aldehydes, both with electron-donating (ED) and electron-withdrawing (EW) substituents. It is worth mentioning that Gd triflate is much cheaper than scandium triflate, and that in this study the so called “gadolinium break” phenomenon [6], a discontinuity in the lanthanide properties

• different combinations of starting materials and elucidating the effect of substituents on each of the partners [1]. Since 2019, research has been focused on broadening its scope with the aim of moving towards a more sustainable chemistry or to impart specific properties to the final products, therefore a

• the tolerability of a wide range of aldehydes, starting from one of the most used, benzaldehyde, passing through heteroaromatic and aliphatic structures with different substituents. In this context, some examples where the aldehyde functionality is incorporated into sugar derivatives, natural

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• of photocatalysts by tuning their redox and photophysical properties. Thus, we successfully developed a one-pot, three-component synthetic method with those substituents in 5-aryldeazaflavins 1 on the deazaisoalloxazine core or on the phenyl ring by condensation of N-substituted anilines, aromatic

• substituents at positions 7 and 8 of the deazaalloxazine ring (see Figure 1 for numeration) showed the best reactivity as reductive photocatalysts. Such an outcome of MCR opens up the possibility of their production on a larger scale for commercial needs. However, the synthesis of the 7- and 8-methoxy

• methyl substituents were chosen to enhance the photophysical properties and photostability of the desired photocatalysts. It should be noted that our method encountered limitations when applying strongly deactivated anilines substituted with CF3 or acetyl groups, with no formation of 5

Chiral bifunctional sulfide-catalyzed enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids

• Sao Sumida,
• Ken Okuno,
• Taiki Mori,
• Yasuaki Furuya and
• Seiji Shirakawa

Beilstein J. Org. Chem. 2024, 20, 1794–1799, doi:10.3762/bjoc.20.158

• without substituents on the carbon–carbon double bond have remained a formidable challenge. To address this limitation, we report herein the asymmetric bromolactonization of 5-hexenoic acid derivatives catalyzed by a BINOL-derived chiral bifunctional sulfide. Keywords: asymmetric catalysis

• to asymmetric halolactonizations, especially for the synthesis of chiral γ-butyrolactones and δ-valerolactones via the reaction of 4-pentenoic acid and 5-hexenoic acid derivatives (Scheme 1). Notably, however, substituents on the carbon–carbon double bond of alkenoic acid substrates are generally

• required to achieve highly enantioselective halolactonizations (Scheme 1a) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Enantioselective halolactonizations of sterically less hindered alkenoic acid substrates without substituents on the carbon–carbon double bond have

Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides

• Samuel M. G. Dearman,
• Xiang Li,
• Yang Li,
• Kuldip Singh and
• Alison M. Stuart

Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157

• contains two trifluoromethyl groups in the sidearm which could alter the electronic effects significantly. We therefore decided to prepare a small series of monocyclic trifluoro(aryl)-λ5-iodanes, where the sidearm substituents were changed stepwise from methyl to trifluoromethyl groups, so that we also

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations

• Alexander V. Tsygankov,
• Vladyslav O. Vereshchak,
• Tetiana O. Savluk,
• Serhiy M. Desenko,
• Valeriia V. Ananieva,
• Oleksandr V. Buravov,
• Yana I. Sakhno,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156

• conventional thermal heating, amide 10a was isolated, albeit in a lower yield and accompanied with tar formation. In addition to the 1H, 13C NMR spectra and mass spectrometry data, the structure of compound 10d was established by X-ray diffraction analysis (Figure 3). It was also found that the substituents at

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• radical (potassium nitrosodisulfonate) [13] or catalytic systems like methyltrioxorhenium(VII) (MeReO3) [14] and 2-iodobenzenesulfonic acids (IBS)/Oxone® [15] led to either p-quinones or o-quinones, depending on the substituents in the para-position to the hydroxy group. Recently, hypervalent iodine

• transfer [50]. Unsubstituted PAHs display multielectron oxidation, but one-electron waves occur with electron-donating substituents in suitable positions. Panizza et al. [38] observed two one-electron oxidations in their cyclic voltammetry studies of 1a in water and proposed the formation of a naphthyloxy