Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• active mono-copper species in the enantio-determining step (Scheme 19). Lin et al. [69] achieved, for the first time, the asymmetric yne-allylic substitution using anthrones as the substrates by using a p-CF3 substituted Pybox ligand, yielding 1,3-enynes containing anthrone units with high

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

• demonstrate the FADH2/FMNH2-dependent nature of AlpJ-family oxygenases when utilizing 1 as the substrate. Intriguingly, these enzymes exhibit notable similarities to cofactor-independent anthrone oxygenases, exemplified by TcmH and ActVA-Orf6, in both protein sequences and structures (see Figure S1

• resemblance of AlpJ-family oxygenases to cofactor-independent anthrone oxygenases rather than to the conventional FADH2-dependent counterparts, we aimed to investigate the potential for catalyzing oxidation reactions in a cofactor-independent manner. For cofactor-independent oxygenases such as TcmH and ActVA

• oxygenases, including anthrone oxygenases such as ActVA-Orf6 and nogalamycin monooxygenase (NMO or SnoaB) [21][23][29][30][31][32], TnmJ and TnmK2 [24], 1-H-3-hydroxy-4-oxoquinaldine-2,4-dioxygenase (HOD) [33][34], and urate oxidase [35][36]. Investigations into NMO and HOD revealed the utilization of

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

• adduct 35 was produced in the reaction with anthrone (34). When the reaction of anthraquinone was carried in THF solution (reflux, 1 h), dibromide 10 remained unchanged. However, a small amount of 33 was formed in refluxing THF by the use of the Zn/Ag couple in the case of anthraquinone. These results

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• dimethyl malonate and its nitro analogue gave benzoheptafulvalene derivatives 52 and 53 [50][63]. The condensation of 4,5-benzotropone (11) and anthrone (10H-anthracen-9-one) also afforded 4,5-benzo-tropyliden-anthron 54 in 65% yield [63]. Kitahara reported the synthesis of 1,2,3,4-tetrachloro-7,8

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• desired product 54 trans-selectively (Scheme 30). In 2016, Xia and co-workers described a metal-free, UV-light-mediated difunctionalisation of alkenes with CF3SO2Na for the synthesis of phenanthrene and anthrone derivatives [53]. The substrates were either α,β-unsaturated ketones 57 (Scheme 31a) or γ,δ

A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis

• Mariano Goldberg,
• Denis Sartakov,
• Jan W. Bats,
• Michael Bolte and
• Michael W. Göbel

Beilstein J. Org. Chem. 2016, 12, 1870–1876, doi:10.3762/bjoc.12.176

• chemical correlation. Keywords: absolute configuration; anthrone; cycloaddition; kinetic resolution; lipase; Introduction In guanidinium ions charge delocalization is an important factor to stabilize the protonated form. As a result, guanidines are exceptionally strong nitrogen bases. As part of the

• the Michael products [19] which are the dominant products in polar solvents [25]. Previous mechanistic studies by Koerner and Rickborn [25] have collected strong arguments for a fast concerted [4 + 2]-cycloaddition of the deprotonated anthrone. Michael products were shown to be secondary products of a

• successfully used as catalysts for anthrone maleimide cycloadditions [29][30][31][32][33][34][35]. In the presence of 10, dichloroanthrone 21 reacted with maleimides 22 and 23 to produce exclusively cycloadducts 26 and 27. In contrast, a mixture of 25 and 28 resulted from the reaction of anthrone 20 and N

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• complexity of these processes, we will focus on the steps directly associated with heterocycle formation [82][83][84]. Aflatoxin B1 (94) is considered as the most toxic aflatoxin. It is derived in multiple enzymatic conversions from norsolorinic acid anthrone 100, which is produced by the norsolorinic acid

C₂-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels- Alder reaction of anthrones

• Deniz Akalay,
• Gerd Dürner,
• Jan W. Bats and
• Michael W. Göbel

Beilstein J. Org. Chem. 2008, 4, No. 28, doi:10.3762/bjoc.4.28

• Brønsted bases in the Diels-Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally

• all subsequent experiments. In the next series of experiments, bisamidines 8a–c and ent-8d were compared as catalysts of the cycloaddition forming 3a from N-phenylmaleimide (2a) and anthrone (1a). Using 0.25 equiv of catalyst at room temperature, isolated yields between 71% and 86% were obtained after

• mechanistic rationalisation is proposed in Scheme 4. The catalyst deprotonates the anthrone in the initial step. This assumption is supported by the pKa values of compounds 2a (10, [7][8]) and 8·H+ (~11, [6]). Furthermore, the appearance of the yellow color of enolates (1·H+) shows significant proton transfer