AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• % yields. For examples, the aromatic motifs of ynamides possessing an electron-donating group such as MeO-, Me- and t-Bu- are well tolerated to afford the desired cycloadducts 10ba–da in 85–99% yields. The ynamide substrates 4e–g with an electron-deficient halogen substituent (F-, Cl- and Br-) on the

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• properties but constitutes also a potential binding motif for Lewis bases. In this context it is well established that the electron-deficient trivalent boron can bind anions, such as fluoride or cyanide, through interaction with the vacant 2pπ orbital [30]. In Figure 4 the fluorescence responses of the dyes

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• their isolation and structural characterization are still less common. A very convenient access to such betaines is provided by the nucleophilic addition of tertiary phosphanes to electron-deficient alkenes, alkynes and allenes (phospha-Michael addition), which generates the betaines as reactive

α,ß-Didehydrosuberoylanilide hydroxamic acid (DDSAHA) as precursor and possible analogue of the anticancer drug SAHA

• Shital K. Chattopadhyay,
• Subhankar Ghosh,
• Sarita Sarkar and
• Kakali Bhadra

Beilstein J. Org. Chem. 2019, 15, 2524–2533, doi:10.3762/bjoc.15.245

• derivative 11a [11]. Cross metathesis (CM) between a terminal alkene and an α,ß-unsaturated carbonyl compound (or similar electron-deficient alkenes) has been used to prepare functionalized alkenes in several occasions [18][19][20]. We have recently reported the CM of a terminal alkene with a hydroxamic acid

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• ]arenes 1 and 12 are more electron deficient than 2 and 22, explaining the weaker affinity of 2 and 22 towards anions. This result is also underpinned by the calculated interaction energies of anionic complexes; −149 kJ/mol ([22 + Iexo]−) vs −175 kJ/mol ([12 + Iexo]−) and −170 kJ/mol ([22 + 2Iexo]2−) vs

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• focused on the preparation and investigation of electron-deficient analogs of the perimidinespirohexadienone (PSHD) family of photochromic molecular switches for potential application as "photochromic photooxidants" for gating sensitivity to photoinduced charge transfer. We previously reported the

• substrates [11][12][13][14][15], or vinylcarbazole or alkoxystyrene derivatives for radical cation cylcloaddition and polymerization reactions [16][17][18][19][20]). We thus proposed the replacement of the naphthalene in 1a with a more electron-deficient quinoline ring. Due to the saturated spirocyclic

• generated LW form of 3a was more negative by 10 mV than that of 2a, even with the more electron-deficient quinoline ring. Presumably this is because the 5-position on the benzene ring of the quinoline, is the least withdrawing point of attachment, and the inductive withdrawing properties of the quinoline

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

• ] extended this approach to the directing-group-assisted copper-catalyzed trifluoromethylation of electron-deficient alkenes (Scheme 72b). Moreover, α-aryl and α-alkyl-substituted acrylate derivatives could be used as substrates to form the C(sp2)–CF3 bond with a complete Z-selectivity. A radical species

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• (DB24C8) are capable of a reversible pH-controlled movement of the crown ether between two stations. UV–vis absorption spectroscopy experiments and 1H NMR spectroscopy have shown that the electron-rich crown ether rings and the electron-deficient N-methyl-1,2,3-triazolium can interact with each other

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• exocyclic C6 position have also been reported. For higher-order hepta- and nonafulvenes, the extended conjugated system also allows them to act as 8π components, as well as 2–6π components. Pentafulvenes can react as 2π components with moderately electron-deficient dienes and 4π components in reactions with

• fulvene to function as a 6π component in reactions with electron-deficient dienes (Scheme 5b) and fulvenes acting as dipolarophiles have been reported for enantioselective [6 + 3] and [3 + 2] cycloadditions [83][84][105]. In general, reactions with electron-rich alkenes will take place preferentially at

Regioselective Pd-catalyzed direct C1- and C2-arylations of lilolidine for the access to 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives

• Hai-Yun Huang,
• Haoran Li,
• Thierry Roisnel,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2019, 15, 2069–2075, doi:10.3762/bjoc.15.204

• PdCl(C3H5)(dppb) catalyst, NaOAc or KOAc as bases in DMA at 150 °C (Scheme 2). We initially studied the reactivity of electron-deficient aryl bromides. Acetyl, propionyl, benzoyl and ester as para-substituents on the aryl bromides were tolerated affording the target products 2–6 in 64–77% yields. The

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• solubilities. The electron-donating diaminoalkyl substituents together with the electron-deficient aromatic core of the naphthalene diimides increase the charge-transfer character of their photoexcited states and thus shift their absorption into the visible light (500–650 nm). The excited state reduction

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• adopt the conformation in which three phthalimide units are cis,trans-orientated. Acting as electron-deficient macrocyclic hosts, the synthesized O6-corona[3]arene[3]tetrazines self-regulated conformational structures to complex anions in the gas phase and in the solid state owing to the anion–π

• functionalized coronarene macrocycles. Moreover, the electronic feature of the phthalimide would render the resulting O6-corona[3]arene[3]tetrazines the electron-deficient hosts to form anion-π complexes [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. We report herein the synthesis, structure

• electrochemical result indicated the occurrence of electronic communication between aromatic rings. The potential for the first redox process (−811 mV) obtained from CV and DPV revealed the electron deficiency of the macrocycle. The resulting electron-deficient O6-corona[3]arene[3]tetrazines prompted us to

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• CO to give an acyl radical C [35], which then adds to electron-deficient sulfonyl oxime ether 3a to afford 5a. The resulting radical D then undergoes β-fragmentation providing 5a along with the phenylsulfonyl radical E. SH2 reaction between radical E and hexabutylditin regenerates the tributyltin

The cyclopropylcarbinyl route to γ-silyl carbocations

• Xavier Creary

Beilstein J. Org. Chem. 2019, 15, 1769–1780, doi:10.3762/bjoc.15.170

• contributed heavily to the development of carbocation chemistry. This article will deal with three types of carbocations that have been of intense and fundamental interest over the years, i.e., cyclopropylcarbinyl cations, electron-deficient cations, and silyl substituted carbocations. A brief overview of

• will deal with is the so-called “electron-deficient” carbocation, i.e., carbocations 9 (Figure 1) substituted with electron-withdrawing groups E [21]. Many studies have shown that such cations can indeed be generated and that they can derive stabilization by a variety of mechanisms. Chief among these

• formed from cations 54 and 74 and not from cations 24, 37, and 52, which do not have electron-withdrawing groups? Previous studies have shown that “electron-deficient” cations 9, where E = COR [66], CN [25], CF3 [67], and PO(OEt)2 [34], readily eliminate β-hydrogens to form alkenes as major products

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

Synthesis of 9-O-arylated berberines via copper-catalyzed C_Ar–O coupling reactions

• Qiaoqiao Teng,
• Xinhui Zhu,
• Qianqian Guo,
• Weihua Jiang,
• Jiang Liu and
• Qi Meng

Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161

• scope was investigated using various aryl iodides (Scheme 3). Both, electron-rich and electron-deficient aryl iodides afforded the corresponding 9-O-arylated tetrahydroberberines 2a–o in good to decent yields. Also, nitro and ester substituents were well-tolerated under these conditions giving the

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• imidates in the presence of 1.5 equiv of acetic acid [20]. When using highly electron-deficient 2-hydrazinopyridines, the [1,2,4]triazolo[4,3-a]pyridines obtained were converted into [1,2,4]triazolo[1,5-a]pyridines. The structures of triazolopyridines 10–12 were confirmed by IR, 1H, 13C, and 31P NMR

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• , indoles [30] or phenols [31]. Other arenes (benzene and its substituted derivatives) have not been involved in these reactions. Concerning electron-deficient allenes, bearing electron-withdrawing groups, there is only one example of a trifluoroacetic acid-promoted hydroarylation with indoles [30]. To the

• best of our knowledge, up to the moment, there are no examples for an intermolecular hydroarylation of electron-deficient allenes by benzene derivatives under the action of strong Brønsted or Lewis acids. The main goals of this work were to study transformations of various phosphorylallenes under

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

• Anthony Choi,
• Rebecca M. Morley and
• Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

• ). The adducts could be reduced, oxidised, or could undergo Suzuki–Miyaura coupling to give different substituted dihydro- and tetrahydroquinoline derivatives. Single crystal X-ray structure for 7c. Single crystal X-ray structure for 9. Reaction of ketone 1 with electron-deficient alkenes 2. Reactions of

• ester 4 and amide 5 with electron-deficient alkenes 6. Reactions of ester 4 and amide 5 with N-methylmaleimide. Reduction and oxidation of adducts 9 and 10. Formation of amides 15a and 15b and Suzuki–Miyaura coupling to yield 16. Supporting Information Supporting Information File 322: Experimental

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• bis(tri-tert-butylphosphine)palladium(0) the yield increased to satisfying 90%. For conversion into the dicarboxylic acid 3, another change of the general procedure was necessary. Probably because of the extremely electron deficient aromatic system in 12a, desilylation at room temperature led to

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• the first title compound 3 in 71% yield. Due to the electron-withdrawing amide group, the chromophore is relatively electron deficient (absorption at 420 nm and emission at 495 nm). In order to achieve a bathochromic shift of absorption and emission bands, the DAT and ALA moieties should be

• NH2 and NHBoc group is the most electron-deficient one with absorption and emission wavelength at 408 nm and 487 nm, respectively (Stokes shift ca. 80 nm). A bathochromic shift of 16 nm of both, absorption and emission wavelengths, is achieved by introduction of a benzyl residue at one nitrogen atom

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• –acceptor [2]rotaxanes such as 19 through liquid-assisted mechanochemical milling (Figure 9). The donor–acceptor interaction between the electron-deficient naphthalene diimide moiety and the electron-rich naphthalene moieties embedded in the macrocyclic polyethers played the vital role for the construction

Efficient synthesis of pyrazolopyridines containing a chromane backbone through domino reaction

• Razieh Navari,
• Saeed Balalaie,
• Saber Mehrparvar,
• Fatemeh Darvish,
• Frank Rominger,
• Fatima Hamdan and
• Sattar Mirzaie

Beilstein J. Org. Chem. 2019, 15, 874–880, doi:10.3762/bjoc.15.85

• synthesized (arylhydrazono)methyl-4H-chromen-4-ones 1a–g have several electron-deficient centers such as at C-2, C-4 and C=N and are susceptible to different intramolecular and intermolecular ring formations. It seems that a proposed mechanism could proceed initially through (arylhydrazono)methyl-4H-chromen-4

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• hypervalent iodine oxidants to mediate benzylic C–H oxidation is one area experiencing a surge of interest [22][23][24][25][26][27][28][29][30][31][32][33]. Nonmetal-based benzylic oxidations have also been mediated by species including, but not limited to, electron deficient quinones, photoexcited organic

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• obtained in 98% yield (Table 1, entries 1–4). Next, we studied the influence of different ligands in terms of electron-rich, electron-deficient substituents and steric hindrance. The results suggested that different ligands had little effect on this reaction (Table 1, entries 5–7). After a further

• conditions in hand (Table 1, entry 3), we expanded the aryl iodide substrates of this reaction (Scheme 2). As a result, it was found that both electron-deficient and electron-rich aryl iodides progressed well in the transformation, and the yield of relevant phenanthrene derivatives y-2–y-15 was quite well