Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• sequential alcoholysis with phenol and benzyl (4-hydroxybutanoyl)glycinate (93), respectively, to give the protected phosphonodepsitripeptide 94. After hydrogenolysis, the free γ-phosphonodepsitripeptide 95 was obtained (Scheme 15) [30]. Seven years later, various enantiopure 2-hydroxyalkanoic acids 96 were

• -aminophosphonodichloride 92 with phenol and methyl (S)-2-hydroxypentanoate (18). All synthetic phosphonodepsipeptides 99, 102, and 104 were considered as glutathione-analogue phosphonopeptides as mechanism-based inhibitors of γ-glutamyl transpeptidase for probing the cysteinyl-glycine binding site (Scheme 16) [31

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• polyhydroxylated molecules of interest (e.g., antioxidants) [4][26] and of novel chromogenic feruloylated substrates with various physicochemical features for screening applications. Accordingly, we observed that transesterifications only occurred when using primary benzylic alcohols; no phenol acylation was

• detected with hydroxynitrobenzylic alcohol (Table 1, no side product of 4 and 9 with transfer on an aromatic secondary alcohol; i.e., phenol), 2-chloro-4-nitrophenol, or 4NTC (data not shown). Additionally, the exact position of the benzyl alcohol affected the transfer, with ortho-substitutions (R1

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• -tetramethyl-1,3,2-dioxaborolane [23]. The electrophilic compound suitable for the projected cross coupling was obtained by mono-demethylation of commercially available 1-bromo-3,5-dimethoxybenzene (7) with boron tribromide (Scheme 3). A satisfactory yield of phenol 8 was observed with 0.9 equivalents of the

• the product with 55% yield. The O-benzylation of phenol 8 furnishing the bromide 9b was accomplished with virtually quantitative yield. Suzuki coupling of the benzyl-protected compounds 6b and 9b led to biaryl 10b with 89% yield; it was deprotected with palladium on charcoal under eight bar hydrogen

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• edge is hydrophobic, while the narrower lower edge is hydrophilic due to the presence of phenolic oxygen atoms. Depending on the number of phenol units, calixarenes have a variable cavity size, and thus are able to combine with different guests. Therefore, calixarenes can be used as effective

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• utility of halothane for the synthesis of aryl gem-difluoroalkyl ethers containing the bromochloromethyl group. Keywords: aryl 1,1-difluoroethyl ether; 1,1-difluoroethene; fluorine compound; halothane; phenol; Introduction Molecules containing fluoroalkyl groups are of interest in pharmaceutical and

• ether was the reaction of phenol with 2-chloro-1,1,1-trifluoroethane, also known as HCFC-133a, in the presence of potassium hydroxide (KOH) to give the gem-difluoromethyl ethers along with the formation of 1-fluoro-2-chlorovinyl ether (route (d), Scheme 1) [41]. On the basis of our previous reports, we

• functionalized aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers as well as several considerations of the reaction mechanism. Results and Discussion We began our study to optimize the reaction conditions (Table 1). When two equivalents of halothane and sodium hydride (NaH) were treated with phenol (1a) at room

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• oxidation of (Z)-15a followed by immediate aldol condensation afforded racemic phenol ester (rac)-17 via aldehyde 16. However, several attempts to form enantioenriched aldol fragment 18 using both a chiral auxiliary [25][26][27][28] and catalytic asymmetric [29][30] procedures proceeded without success

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• needed. In this work, we present a novel heterogeneous Cu catalyst using modified LS as support by a consecutive process involving the phenol–aldehyde condensation of LS with 2-formylbenzenesulfonic acid sodium (FAS), ion exchange and acidification. Special interest is given in the application of the

• , the support was prepared through phenol–formaldehyde condensation reaction of LS and FAS. The FAS was chosen to embellish LS in consideration of the following reason: FAS skeleton consists of both aldehyde and sulfonic groups, so the grafting of FAS and LS can be easily realized via phenol

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• conditions and the kinetics of the selected reaction can lead to drastic changes in the PSTY. de Sá et al. combined external and internal numbering up in meso- and microchemical reactors of various sizes (Figure 3e). Photocatalytic degradations of methylene blue, rhodamine B, and phenol with TiO2 were

• reactants, the light distribution throughout the catalyst layer, and the reaction rate. Leblebici et al. [49] showed that increasing the flow rate of the reactants did not increase the apparent reaction rate for phenol degradation in an immobilized photoreactor. Increasing the flow rate would result in a

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• donor than the phenol group [52][53]. Furthermore, trifluoroacetic acid (TFA) was added to a solution containing the deprotonated forms of dyes 8–12 in DMSO, so as to investigate the reversible protonation of the dyes. As can be seen in Figure 5, the addition of 5 equiv of TFA to a basic solution of 12

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• 74 into the stable derivatives 75 having a strong C–C bond through the nucleophilic substitution reaction with phenol and anisole in the presence of trifluoromethanesulfonic acid (TfOH) with total stereoinversion. This suggests that the nucleophile attacks occur from the concave face of the π-bowl

• [48]. Although, for the nucleophilic substitution reaction with phenol derivatives, they have tried several reaction conditions including the amount of acid as well as phenols. After several experimentations, they found that 30 equivalents of phenol and 1 equivalent of TfOH at 0 °C provided the best

• formation was observed. Therefore, they used a Pd-catalyzed carbonylative esterification in the presence of phenyl formate which in situ generated CO and phenol to provide the required product 97 in 73% yield (Scheme 24). In an independent work reported in 2017, Fukushima and co-workers detailed the

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• temperature, and this was stirred for 2 hours following the same procedure as before. At the final stage, we cleaved the peptide from the resin by using a proper cleavage cocktail: TFA/phenol/water/TIPS 88:5:5:2. DTT was included, as this peptide contains cysteine. After adding the cleavage cocktail to the

• different concentrations at pH 7.4. Detailed synthetic scheme for PEP-1. (i) 20% piperidine in DMF, (ii) HBTU, (iii) NMM, (iv) Ac2O/Py/DMF 1:2:3 and (v) TFA/phenol/water/TIPS 88:5:5:2. Supporting Information Supporting Information File 374: Materials and methods as well as additional figures. Funding G. G

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• -glutamine and phenol red (Fujifilm Wako Pure Chemical, 041-29775), supplemented with 10% fatal bovine serum, 100 units/mL penicillin, 100 μg/mL streptomycin, 0.25 μg/mL amphotericin B (Fujifilm Wako Pure Chemical, 161-23181), and 100 μg/mL gentamicin sulfate (Fujifilm Wako Pure Chemical, 078-06061). The

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• calcinated at 400–500 °C to remove the organic material and form pure TiO2 nanofibers, which were applied for the photocatalytic degradation of phenol [153]. Photodeposition is commonly used to deposit metal atoms or nanoparticles on semiconductor surfaces, which can greatly influence the photophysical

• to achieve a superreducing electronic excited state capable of reducing stable aryl halides (Figure 14) [193]. More recently, PDI self-assemblies have been reported as efficient HPCats for the hydrogen evolution reaction [194] and degradation of phenol [192]. Another important material design applied

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• of the di-tert-butyliminoxyl radical with phenol and its derivatives are faster than with alkenes. The highest reaction rates are observed in the case of electron-donating substituents (Y) in 4-YC6H4OH [35][78]. The hydrogen atom abstraction rate accelerating effect of electron-donating substituents

• was explained by the decrease of the O–H bond dissociation energy by the electron-donating substituent Y [35][79][80][81][82][83][84]. The result of these reactions depends on the phenol structure. 4-Methylphenol (27a) and 2,6-di-tert-butyl-4-methylphenol (BHT, 27b) gave 4-methyl-4

• -iminooxycyclohexadienones 28a,b (Scheme 12). Phenol (29) and 1-naphthol (30) were transformed into 4,4-bisoximes 31 and 32, respectively (Scheme 12) [35][78]. Imines 37–40 were obtained with good yields by the reaction of di-tert-butyliminoxyl radicals with primary and secondary amines 33–36 for several hours at room

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• be produced by salt templating or ultrasonic spray pyrolysis as well as by microwave irradiation. The resulting activated carbon materials are characterized by a variety of techniques such as SEM, FTIR, nitrogen adsorption, Boehm titrations, adsorption of phenol, methylene blue and iodine, TPD, CHNS

• aerosol-assisted self-assembly using amphiphilic triblock copolymers as template and low-molecular weight soluble phenol resin as carbon source. The amphiphilic surfactant influences the pore size and mesostructure of the resulting spherical carbons. Finally, the template is removed by calcination [97

• groups and simultaneously increase of basic properties [10]. Phenol, methylene blue and iodine adsorption: Adsorption capacity and amount of pores of activated carbon materials are determined by using different adsorbates (phenol, methylene blue and iodine). The activated carbons are added to defined

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• synthesis of a Zr-based MOF with meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) (MOF-525, Zr6(OH)4O4(C48N4O8H26)3) [42] and showed its photocatalytic efficiency for oxidative hydroxylation of arylboronic acids [43]. The phenol products were obtained in quantitative yields for all evaluated arylboronic acids

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• could be circumvented through ligand modification. Phenol oxidation is ubiquitous in biological systems as demonstrated by the involvement of the copper enzymes tyrosinases (type III) in the melanogenesis process. The regioselectivity and reactivity of the oxidation of phenols are strongly dependent on

• the phenol substrate substitution pattern, and it is therefore difficult to develop general methods for this transformation. This substrate–control bias was successfully outmaneuvered by the development of a copper-based catalytic system operating under aerobic conditions and allowing selective access

• metalloenzymatic active site was not characterized in detail, it might bear some resemblance to the original biological active site. Building on their previously discussed phenol oxidation methodology (Scheme 5 and Scheme 6), Lumb and co-workers have targeted subsequent C–N bond formation to access oxindoles [34

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• equivalent to dienones (Scheme 29). In this case, however, instead of forming an enol, a highly stable phenol resulted from the addition of silicon at the methide position. The reaction was exclusively done on electron-rich systems 163–166. Nonetheless, further functionalization of one of the silicon

• -containing products (166) was carried out to arrive at the keto phenol derivative 167. Loh, Xu, and co-workers [66] explored related reactions involving unsaturated ketimines using copper triflate or copper bis(4-cyclohexylbutyrate) (Cu(CHB)2) to prepare allylic silanes. Interestingly, using one or the other

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• (Scheme 2). Therefore, 4-hydroxybenzaldehyde (12) was chlorinated and phenol 13 was protected as TBS ether to afford aldehyde 14 which was then converted into dibromoolefine 15 in good yields using the Corey–Fuchs protocol. Uenishi et al. [21] published an effective way of defunctionalizing dihalogenated

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• phenol 8 was generated by the reaction of 2-hydroxybenzaldehyde (5) and o‐phenylenediamine (7) at rt using a cobalt catalyst. In the next step, a benzimidazole-containing aldehyde 9 was obtained by the reaction of 6 with benzimidazole-substituted phenol 8. This ligand was immobilized on propylamine

• employed in diverse organic reactions, including Suzuki reactions [64], Sonogashira reactions [65], transesterifications of triglycerides [66], hydrogenation reactions [67], N-heterocycle syntheses [68], cleavage of propargyl phenol ethers [69], etc. [70][71][72][73][74][75]. In this review article, we

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• , Sapporo, Hokkaido 001-0021, Japan 10.3762/bjoc.16.50 Abstract A chiral phenol–NHC ligand enabled the copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters. The phenol moiety of the chiral NHC ligand played a critical role in producing the enantiomerically enriched products. The

• , while an achiral NHC/copper catalyst has successfully been utilized in this reaction [13]. Meanwhile, we devoted our effort to develop novel enantioselective C–C bond formation reactions utilizing chiral phenol–NHC/copper catalyst systems [14][15][16][17][18], in which the phenol group of the NHC ligand

• plays crucial roles in both the catalytic activity and stereoselectivity [19][20][21]. Notably, these catalyst systems were also applicable for three-component coupling reactions using hydrosilanes as hydride reagents [17]. Based on this knowledge, we decided to investigate the effects of the phenol–NHC

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• using cesium carbonate as base in DMF at 40 °C [42], giving both the enantiomers of 2 in optically pure forms. The remaining fluorine substituents were subsequently replaced by a series of phenols including unsubstituted phenol, p-tert-butylphenol, and m-tert-butylphenol to produce the corresponding

• at 250.0 nm. Preparation of 3a–c Compound 3a: To a 10 mL Schlenk flask were added 2 (294 mg, 0.5 mmol), phenol (103 mg, 1.1 mmol), and Cs2CO3 (358 mg, 1.1 mmol). DMSO (3.5 mL) was added via the syringe. The mixture was stirred at 100 °C for 18 h under N2. The resulting mixture was extracted with

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• -worker’s results [86], in 2015, Rueping and co-workers reported reoxidation reactions via visible photoredox catalysis [87]. In their study, they used photoredox catalyst 9 along with a Ru catalyst for ortho C–H functionalization of phenol derivatives, viz, ortho-(2-pyridyl)phenols (Pyr, Scheme 2

• ). Captivatingly, in the absence of a photoredox catalyst, poor yields were obtained, and no reoxidation happened. On the other hand, quite recently, the same group reported on the conversion of phenol derivatives using dual semiconductor photoredox catalysis for C–H bond functionalizations, which was proved to be

• catalysts was also reported, and this approach allowed for easy and fast transformations to take place. Herein, we cover all the reported strategies for aryl para C–H bond functionalizations by means of photoredox catalysis. Aryl C–H hydroxylation: synthesis of substituted phenols The synthesis of phenol

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

• Jucleiton J. R. Freitas,
• Queila P. S. B. Freitas,
• Silvia R. C. P. Andrade,
• Juliano C. R. Freitas,
• Roberta A. Oliveira and
• Paulo H. Menezes

Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

• method was evaluated using aldehydes containing different functionalities. For example, the use of vanillin, an aldehyde containing the acidic phenol group as substituent, gave the corresponding product 2o in 93% yield in an 82:18 ratio of regioisomers. In the same way, when aldehydes containing an ester