Me₃Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines

• Krishna M. S. Adusumalli,
• Lakshmi N. S. Konidena,
• Hima B. Gandham,
• Krishnaiah Kumari,
• Krishna R. Valluru,
• Satya K. R. Nidasanametla,
• Venkateswara R. Battula and
• Hari K. Namballa

Beilstein J. Org. Chem. 2021, 17, 2765–2772, doi:10.3762/bjoc.17.186

• appropriate ester of benzoic acid in the presence of a base. After having the starting material in hand, we commenced our investigations for the synthesis of 1-aminoisoquinolines by treating 2-(2-oxo-2-phenylethyl)benzonitrile (3a) with aniline (4a) in the presence of different Lewis acids under varying

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

• Akhil K. Dubey and
• Raghunath Chowdhury

Beilstein J. Org. Chem. 2021, 17, 2642–2649, doi:10.3762/bjoc.17.177

• nitromethane under the optimized reaction conditions. Pleasingly, using 9-amino-9-deoxyepihydroquinidine (IX)–benzoic acid as organocatalyst system (see Supporting Information File 1 for details) promoted the addition reaction and product 3l was formed in good yield (79%) and excellent enantioselectivity (99

• phase. dEnantiomers could not be separated by AD-H, OD-H, OJ-H, and AS-H columns. eReaction conditions for 3l: 1l (0.2 mmol), 2 (2 mmol), catalyst IX (0.04 mmol, 20 mol %), benzoic acid (0.08 mmol, 40 mol %) in 0.9 mL toluene as the solvent (see Supporting Information File 1). fMalonitrile (0.6 mmol, 3

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• flash column chromatography using silica gel as stationary phase. Mechanochemical procedure for enantioselective Michael additions The catalyst (0.016 mmol), base (0.016 mmol), nitroalkene (0.33 mmol), appropriate aldehyde (1 mmol), benzoic acid (0.03 mmol), and NaCl (1.2 g) were added to the ball mill

• . After further 5 min stirring, benzoic acid (10 mol %) was added and 10 min later, the nitroalkene (1 equiv) was added. The resulting reaction mixture was stirred at room temperature for the appropriate reaction time. The crude reaction mixture was purified by column chromatography using silica gel

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• of prolinol silyl ether (cat. 120) and benzoic acid (A1) catalysts to bring about reaction between 3-formyl-substituted indoles or pyrroles 118 and diverse electrophiles, including carbonyls, imines and other Michael acceptors (Scheme 5) [69]. The reaction with secondary amines occurred via the

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• , iron(III) chloride hexahydrate, trifluoroacetic acid (TFA), N-trifylphosphoramide (NTPA), benzoic acid, diphenyl phosphate (DPP), malonic acid, chloroacetic acid, copper(II) triflate, acetic acid, and p-toluenesulfonic acid (p-TSA) were used as catalysts. TFA gave the best yield of these catalysts with

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• reaction also included anthraquinones 173b and 173c, obtained in good yields (74–94%) [73]. In 2015, in a related approach, Lee et al. disclosed a direct one-pot synthesis of anthraquinones and tetracenediones by using ʟ-proline as organocatalyst and benzoic acid as additive (Scheme 40) [74]. They

• authors observed that benzoic acid played an important role in the formation of quinone compounds, increasing the yields and decreasing reaction times [74]. Recently, Takeuchi’s research group synthesized polysubstituted anthraquinones 179 in moderate to good yields (42–93%) via an iridium-catalyzed [2

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• mixture of E/Z isomers. Further, double bond cleavage of nucleoside 120 followed by benzoylation produced the benzoic acid ester of the hemiacetal analogue 121 which was finally converted into double-headed nucleoside 122 via Vorbrüggen coupling reaction followed by deprotection using methanolic ammonia

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• of benzoic acid at an elevated temperature yielding lactam 6 almost quantitatively. The deoxygenative reduction of this compound turned out to be challenging, as the typical procedure using LiAlH4 proved ineffective. We were able to obtain 7 using a Schwartz’s reagent-mediated amide activation

Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

• Vladimir Ilkin,
• Vera Berseneva,
• Tetyana Beryozkina,
• Tatiana Glukhareva,
• Lidia Dianova,
• Wim Dehaen,
• Eugenia Seliverstova and
• Vasiliy Bakulev

Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243

• thioamides with sulfonyl azides [33][41][42] (Figure 2). This method was used successfully for the synthesis of N-sulfonyl amidines of aliphatic acids and benzoic acid, including biologically active compounds. On the other hand, reactions of thioamides with electrophilic reagents have often been used for the

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• the UVRR binding studies without an interference from the disturbing UV-excited autofluorescence, benzoic acid (BA) was chosen as an aromatic binding partner for GCI. We also present the UVRR results from the binding of GCI to the ubiquitous RGD sequence (arginylglycylaspartic acid) as a biologically

• spectrally separating the UVRR signal (below 260 nm) from the UV-excited autofluorescence starting from ca. 260 nm (cf. Figure 2) [22]. We employ two different carboxylates for the UVRR binding studies: benzoic acid (BA) as an aromatic model system and the ubiquitous RGD sequence (arginylglycylaspartic acid

• using two different carboxylates as the binding partners. We choose an aromatic binding partner, benzoic acid, for which the UV-excited autofluorescence might disturb the Raman signal at higher excitation wavelengths. For the second binding experiment we choose a biologically relevant peptide, RGD. In

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• catalysts, this group found that the intramolecular oxa-Michael addition using 20 mol % of the diarylprolinol organocatalyst 37 in the presence of benzoic acid gave 38. The use of the enantiomer of 37 gave the dihydropyran with the opposite configuration at C-11. The catalytic hydrogenation of 38 proceeded

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• components (Scheme 2). The product 8a obtained from benzoic acid, phenylglyoxal, benzylamine, and tert-butyl isocyanide was selected for the screening of the reaction parameters (Table 3). The overall process was conducted in a two-step one-pot fashion as was originally designed by Shibata. In the first step

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• ]. Further, the amount of basic sites on the catalyst was estimated by titration using a standard benzoic acid solution and bromothymol blue indicator. Initially, the catalyst (50 mg) was stirred with the methanolic solution of the indicator (5 mL) for 30–40 min, and then, the mixture was titrated with a

• 0.02 M benzoic acid solution. From the titer values of the benzoic acid solution, the amount of the basic sites was found to be 0.033 mmol/g. The powder XRD pattern of the NDL catalyst is shown in Figure 2. The diffraction peaks at 2θ = 23.16, 29.51, 31.05, 36.02, 38.07, 39.40, 43.0, 47.2, 47.5, 48.5

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• perfluoroalkyl benzoic acid derivatives. A plausible mechanism for the perfluoroalkylation of N-(quinolin-8-yl)benzamides is proposed in Figure 34. First, C–H activation of the benzamide substrate with copper produces a cyclometalated complex. Meanwhile, perfluoroalkyl radicals are generated by electron transfer

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• corresponding mesylated thietane-fused nucleosides 128 and 131, which generated the final thietane-fused nucleosides 129 and 132 after the reactions with benzoic acid and CsF and subsequent aminolysis [54] (Scheme 25). The methyl 2,3-anhydro-α- and β-D-ribofuranosides 133 were used as starting materials and

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• -hydroxybenzaldehyde phenylhydrazone [52] or a mixture of benzoic acid and 4-(phenylazo)diphenylamine [53]. Iodine can also be used [54]. Similar concentrations were obtained by NMR titration with 1,5-cyclooctadiene as a standard (Section 1.2.10 in Supporting Information File 1) [55]. The heat released from the

• corresponding alcohol (1.0 equiv) and turbo Grignard (1.2 equiv) under flow conditions at 25 °C (Scheme 3). For t-AmylOMgCl⋅LiCl, the concentration was determined using a mixture of benzoic acid and thymolphthalein as an indicator [70]. 6 On-demand reagent proof of concept Objective: To reiterate the turbo

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• benzoic acid (monitored by TLC), the corresponding arylamines (1.5 equiv) were added, followed by the addition of triethylamine (2.0 equiv) in DCM (10 mL). After that the resulting reaction mixture was stirred for 20 h at room temperature and checked by TLC for reaction completion. The reaction mixture

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• , to the amide 83, as shown in Scheme 22. The low yield of the amide formation was attributed mainly to a concurrent imine formation, which was catalyzed by benzoic acid formed as a result of benzaldehyde (8) oxidation during the photoreaction. There was also a competition between two bimolecular

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• first pKa value of substituted piperazines falls in the range ca. 4–6 (vs 9–10 for the second pKa value) [22]. In addition, the electron-withdrawing bromine atoms were also expected to lower the azonium ion’s pKa value (the pKa values of 2-bromobenzoic acid and unsubstituted benzoic acid are 2.85 and

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• employed methods: synthesis of the phenyl-substituted silicon rhodamine 22 by Suzuki cross coupling affords the product in a similar yield compared to the addition of phenyllithium to xanthone 12 or the attack of the double metallated bis-aniline 4 (R1 = R2 = Me, M = Mg) to the benzoic acid methyl ester

Perspective isomorphs – a new classification of molecular structures based on artistic and chemical concepts

• Jannis Neumann,
• Ansgar Schnurr and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2019, 15, 2319–2326, doi:10.3762/bjoc.15.224

• , however, be placed into a different PI class, when viewed from a different angle. This way, they are perspective isomorphe with 4-fluorobiphenyl or benzoic acid. Nomenclature/coding of perspective isomorphs In order to make the concept of perspective isomorphs practicable and unmistakably understandable

• to a group on the left: 1,2-dihydroxybenzene, 1,2-difluorobenzene, naphthalene. Molecules that can be allocated to a group on the right: diphenylacetylene, 4-fluorobiphenyl, benzoic acid. Molecules that can be allocated to both groups: benzene (not shown), phenol, fluorobenzene (the arrows in red and

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• functionalization reactions. Aryl C–H fluorination with various directing groups: With Pd(OTf)2(MeCN)4 and N-methyl-2-pyrrolidinone (NMP) used as the catalyst system, in 2011 the Yu group [57] described the ortho-fluorination of benzoic acid substrates with a directing group, an electron-deficient removable acidic

• amide (Scheme 19). With this method, both mono- and difluorinated benzoic acid derivatives can be selectively obtained in high yields. In 2014, Pu and co-workers [58] devised the regioselective Pd(PPh3)4-catalyzed electrophilic ortho-fluorination of 2-arylbenzothiazoles with NFSI and ʟ-proline as the

• transformation is proposed in Scheme 33 below. Notably, Cu acts as both a mediator and an oxidizer in this reaction. In the same year, Daugulis et al. [78] presented a Cu-catalyzed selective fluorination of benzoic acid derivatives and benzylamine derivatives assisted by an aminoquinoline auxiliary. With a CuI

Friedel–Crafts approach to the one-pot synthesis of methoxy-substituted thioxanthylium salts

• Kenta Tanaka,
• Yuta Tanaka,
• Mami Kishimoto,
• Yujiro Hoshino and
• Kiyoshi Honda

Beilstein J. Org. Chem. 2019, 15, 2105–2112, doi:10.3762/bjoc.15.208

• the product 3a in 82% yield (Table 1, entries 10–12). Decreasing the amount of TfOH did not improve the yield (Table 1, entry 13). It is suggested that the cyclization and dehydration were efficiently promoted at high temperature. Fortunately, when the reaction was carried out with benzoic acid, which

• is a more easily available substrate in comparison with benzyl chloride, the desired product was obtained in good yield. It was found that the reaction can be applied to not only benzoyl chloride but also to benzoic acid. With the optimized conditions in hand, we investigated the generality of diaryl