Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• evaluated for the preparation of tris(arylazo)benzenes 3. The first one relied on the consecutive condensation of anilines with nitroso compounds, Baeyer–Mills reactions [13]. With a suitable protecting group strategy, the selective construction of the individual AB branches should be achievable (Scheme 1

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

• Hoang Huy Do,
• Saif Ullah,
• Alexander Villinger,
• Joanna Lecka,
• Jean Sévigny,
• Peter Ehlers,
• Jamshed Iqbal and
• Peter Langer

Beilstein J. Org. Chem. 2019, 15, 2830–2839, doi:10.3762/bjoc.15.276

• anilines as reagents, we also successfully employed alkyl- and benzylamines which required an additional optimization of the conditions and the employment of different ligands. Therefore, we feel that our approach is more general and merits publication. In addition to the synthetic work, we report, for the

• of the reaction of 3 was studied using different amines. The reaction of 3 with various anilines afforded products 5a–g in good to excellent yields (Table 2). No impact of the functional groups of the anilines on the yield was observed. The reactions of 3 with aliphatic or benzylic amines under our

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• then underwent a regioselective monodeprotection to generate a lone phenol group. The phenolate was reacted with 1,2-dibromoethane and the nitrobenzene groups were reduced to the corresponding anilines giving 1a. The double aniline 1a was alkylated using ethyl bromoacetate under basic conditions in

• acetonitrile, forming the BAPTA precursor 1b. The palladium-catalyzed benzyl cleavage was followed by a double alkylation with 2, reactant 2 being synthesized from 4-(4-nitrophenyl)butanoic acid. The 4-nitrobenzene groups of the pendant arms were subsequently reduced yielding the corresponding anilines (1e). A

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

• efficient method to access ortho-CF3 acetanilides and anilines (Scheme 66b). Recently, Wang and co-workers [127] reported a visible-light-induced Pd-catalyzed ortho-trifluoromethylation of acetanilides. Without the need of an external photocatalyst and additive, various N-substituted anilides and

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• present protocol, various anilines were also utilized which yielded the corresponding amides in moderate to good yields (Scheme 4, 7a–g). Variously substituted anilines with electron-donating and electron-withdrawing groups such as –OCH3, –Cl, and –NO2 were well tolerated under the optimized reaction

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• the past few years [57]. Recently, Buchwald and Castillo have reviewed the exceptional utility of Pd-catalyzed C–N cross-coupling reactions for the preparation of anilines and aniline derivatives [58]. In many of the reactions, palladium was used along with a co-catalyst to enhance its catalytic

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• as the optimized reaction conditions. With optimized reaction conditions in hand, we set out to explore the scope and limitations of the asymmetric reaction (Scheme 1). Initially, we examined the reaction of various anilines with furylcarbinol 1a. Scheme 1 summarizes the results obtained with ortho

• -, meta-, and para-substituted aniline derivatives. The reaction of anilines bearing an electron-withdrawing group at the para-position afforded the optimal balance between efficiency and enantioselectivity. Consistent with Rueping’s work [35], ortho-aminobenzoic acid, which contains an additional

• -Piancatelli reaction. Asymmetric aza-Piancatelli rearrangement with a range of substituted anilines. *To simplify the purification process, carboxylic acids were transformed in situ into the corresponding methyl ester using (trimethylsilyl)diazomethane. Asymmetric aza-Piancatelli rearrangement with a range of

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• acquiring the optimized reaction conditions, we next turned our attention to the reaction scope. A series of investigations was performed to prepare various types of pyrroloacridines (Scheme 1). We first scrutinized a variety of anilines having different types of electron-donating or electron-withdrawing

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• byproducts – likely due to the poor reactivity of the substituted anilines as amino components of the Ugi-4CR. Nonetheless, the Passerini products were also evaluated and provided important information of the structure–activity relationship [24]. An additional library was built by performing the Ugi-4CR at a

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• the feasibility of S-cyclopropylating 4-tert-butylbenzenethiol (14a) with cyclopropylboronic acid (25) using reaction conditions developed by Neuville and Zhu for the N-cyclopropylation of anilines and amines [39]. Treating thiophenol 14a with 2.0 equivalents of cyclopropylboronic acid (25), 1.0

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• - and meta-substituted anilines 2 did not produce isoindolinones 32, and aliphatic amines only reacted when p-toluenesulfonic acid was present. The reaction has also been applied to 1,3-dicarbonyl compounds, however, only residual amounts of isoindolinones 32 were detected and deamination products

• in this manner, although, once again, ortho-substituted anilines 2 did not render the cyclic product, as the final lactamization step is probably impeded by sterical reasons. On the other hand, silyl enol ethers of acetone, acetophenone, methyl acetate, 2-hydroxyfuran and cyclohexanone worked well

A three-component, Zn(OTf)₂-mediated entry into trisubstituted 2-aminoimidazoles

• Alexei Lukin,
• Anna Bakholdina,
• Anna Kryukova,
• Alexander Sapegin and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2019, 15, 1061–1064, doi:10.3762/bjoc.15.103

• isocyanates. However, its scope is limited to aliphatic amines as the reaction failed to work for anilines (even electron-rich ones, such as p-anisidine). The tolerance of acid-labile protecting groups such as Boc is particularly useful as it offers an opportunity for further side-chain modifications. From

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• , nitrosoquinoxaline 3 was synthesized in a two-step procedure starting from 2-chloroquinoxaline (1), which was transformed into its oxime 2 using hydroxylammonium chloride [64]. The subsequent oxidation was performed using periodic acid as oxidant [65]. The subsequent reaction with differently substituted anilines in

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• development does not allow yet to introduce arylamino moieties at C(2) due to the diminished nucleophilicity of anilines. The 7-deazapurine derivatives were characterized with a somewhat larger Stokes shift and bathochromic shift of the lowest energy absorption band in comparison to purine derivatives, but

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• sulfur bridge is oxidized to the sulfoxide or sulfone. Hence, neither reductive nor oxidative conditions are compatible with the –CH2-S– bridge. An alternative strategy, that applies weakly acidic conditions is the condensation of aryl nitroso compounds with anilines. This Baeyer–Mills reaction was

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• -methyl-1H-imidazolium chloride (66) ILs were used as excellent catalysts and the reaction medium for microwave synthesis of quinoline derivatives 65 from substituted anilines 15 and glycerol (64, Scheme 11). Some advantages of these catalytic systems include: elimination of oxidizing agents, ease of

• protected aniline derivatives were obtained by the solvent-free reaction of anilines with 1,3-diketones at 120 °C or 140 °C in the presence of 2 equiv of water under 1 atm O2 atmosphere (Scheme 16). The probable reaction pathway for this reaction is shown in Scheme 16. Arylamine 15 attacks the activated

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• -quinolones 8l–n. Finally, we decided to investigate the reactions of Ugi adducts 7o–r derived from various electron-rich anilines 6. The gold-catalyzed cyclization of 3,4,5-trimethoxyaniline-derived substrate 7o proceeded at the elevated temperature of 50 °C producing 2-quinolone 8o in 89% yield. The

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• ]. However, N-aryl-3,4-DHQs were not accessible through these routes. There are very few reported strategies for the synthesis of C4-unsubstituted N-aryl-3,4-DHQs, and all of them show limitations. The classical method involves the reaction between p-substituted anilines and paraformaldehyde in mineral [42

Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal

• Antonio Arcadi,
• Sandro Cacchi,
• Giancarlo Fabrizi,
• Francesca Ghirga,
• Antonella Goggiamani,
• Antonia Iazzetti and
• Fabio Marinelli

Beilstein J. Org. Chem. 2018, 14, 2411–2417, doi:10.3762/bjoc.14.218

• )anilines 15 (see below). Results and Discussion We have previously reported that arylboronic acids 12 can be used in place of aryl halides in the Pd-catalyzed synthesis of indoles through aminopalladation/reductive elimination reaction from 2-alkynyltrifluoroacetanilides [24]. This reaction is carried out

• = R3, R2 = H) were obtained by cyclization of the corresponding o-(o-aminophenylethynyl)anilines 15a–c with PdCl2(MeCN)2 [29][30]. Indoles 14d,e (R1 ≠ R3) could not be obtained in such way (due to the lack of selectivity between the two different NH2 groups in the hydroamination reaction), and were

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• using several arylamines and hypervalent iodine(V) reagents by direct mixing is unrealistic because of the high exothermic reaction or explosion. Herein we demonstrate, when anilines were substituted with an amide group at the ortho-position, successful chemical reactions could be performed due to

• . Anilines readily reacted with oxone leading to the formation of the azo derivatives [32], while their treatment with IBX led to explosive decomposition. The reactions of 2-aminobenzamide with arylaldehydes in the presence of IBX afforded quinazolin-4(3H)-ones at maximum contact of the reactants, i.e

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• population of dynamic product mixtures was successfully defined. Under low temperature conditions, the rearrangement was largely suppressed. For 1-phenyl-1H-1,2,3-triazole-4-carbaldehyde, the condensation efficiency increased with increasingly electron-rich anilines, and no rearrangements were observed

• this purpose. While 1c showed scrambled substituents under the conditions studied when partnered with anilines with both electron-poor and electron-rich character, 1a efficiently drove the reaction mixture towards rearranged, non-nitro products. It was hypothesized that in addition to promoting the

• -nitroaniline is released as a byproduct, and not each step individually. As summarized in Table 3, it was observed that reaction rates were influenced by both electronic and steric properties of the amine reactant. A comparison of anilines showed that reaction rates decreased with increasing steric bulk at the

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• publication by Kundu and Ranu provides a way of arylating the C2 position of electron-rich five-membered heterocycles, using anilines as the coupling partner. tert-Butyl nitrite (t-BuONO) is used as a diazotizing agent to generate diazonium salts transiently in situ. The reaction is catalysed by Eosin Y under

• irradiation with blue LEDs at room temperature (Scheme 7) [48]. The authors report that in general their procedure allowed for better transformation of electron-poor anilines compared to their electron-rich counterparts. Unfortunately, it is also reported that the scope of the reaction cannot be extended to

• to both the electronics of the arene and the nucleophilicity of the amine. Particularly electron-rich arenes such as N-methylindole are not tolerated, as is the case for relatively nucleophilic amines such as imidazoles, anilines or alkylamines. The reported substrates are particularly valuable to

Cationic cobalt-catalyzed [1,3]-rearrangement of N-alkoxycarbonyloxyanilines

• Itaru Nakamura,
• Mao Owada,
• Takeru Jo and
• Masahiro Terada

Beilstein J. Org. Chem. 2018, 14, 1972–1979, doi:10.3762/bjoc.14.172

• labelling experiments indicate that the rearrangement of the alkoxycarbonyloxy group proceeds in [1,3]-manner. In this article, we discuss the overall picture of the cobalt-catalysed [1,3]-rearrangement reaction including details of the reaction conditions and substrate scope. Keywords: anilines; cobalt

• ]. Further mechanistic studies are underway in our laboratory. Conclusion The cationic cobalt catalysts enabled the rearrangement reaction of N-alkoxycarbonyloxyanilines to proceed under much milder reaction conditions, expanding the substrate scope to more electron-deficient anilines. More importantly, the

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3⁺ + 2]-cycloaddition/rearrangement reactions

• Lin-bo Luan,
• Zi-jie Song,
• Zhi-ming Li and
• Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

• illustrated in Scheme 1, the preparation starts from the related anilines 1 which were acylated with 3-bromopropionyl chloride (2) to afford amides 3. Upon basic treatment with t-BuONa, the amides 3 were converted to the cyclized β-propiolactams 4. In the presence of triflic acid, the Fries rearrangement

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• cyclic diaryl-λ3-iodanes (Scheme 26) [66]. The palladium phosphine ligand plays a crucial role as a bidentate ligand with a bite angle greater than 100° such as DPEphos (104°) or Xantphos (108°) significantly improves the yields. The reaction applies to a series of anilines and aliphatic amines, but

• electron-poor anilines afford better results than their electron-rich congeners, while a hindered amine (t-BuNH2) completely inhibits the reaction. Shortly after, a similar synthesis of carbazoles involving Cu(OAc)2 as the catalyst in the presence of ethylene glycol both as a ligand and the co-solvent has

• been reported (Scheme 27) [67]. A variety of amines such as anilines, sulfonamides and aliphatic amines has been utilized though in large excess. But in contrast to the previous method, electron-rich anilines proved to be better candidates for this reaction than the electron-poor analogs. The group of