Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• are also cyclitol derivatives, in which one of the hydroxy groups is replaced by a halogen. They have also attracted interest in the last decade because of their biological activities [11][19]. For instance, some brominated quercitol (cyclohexanepentol) derivatives and bromoconduritol-B act as strong

• bromo groups, while the halogen functionality was introduced to the molecule by opening of the epoxide ring with HBr(g) or HCl(g) in MeOH. Structures of some important aminocyclitols. Synthesis of cyclic sulfate 9. Synthesis of aminocyclooctanetriol 12. Synthesis of aminocyclooctanetriol 18. Synthesis

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• methylene function in halo-substituted substrates and with facilitation of bases, methanofullerenes with various structures are formed rather smoothly. It is believed that nucleophilic addition of an α-halocarbanion to C60 occurs initially, followed by intramolecular substitution of the halogen atom by an

The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst

• Deniz Tözendemir and
• Cihangir Tanyeli

Beilstein J. Org. Chem. 2021, 17, 494–503, doi:10.3762/bjoc.17.43

• ). The solvent effects on the SMA of the chalcone derivatives and naphthalene-1-thiol are summarized in Figure 2. This behavior might be related to the better stabilization of the transition state of the substrates containing electron-withdrawing substituents or halogen atoms with THF, or vice versa. In

Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system

• Yamato Fujihira,
• Yumeng Liang,
• Makoto Ono,
• Kazuki Hirano,
• Takumi Kagawa and
• Norio Shibata

Beilstein J. Org. Chem. 2021, 17, 431–438, doi:10.3762/bjoc.17.39

• ketone 2b in only lower yield (37%). Functionalities on the benzene ring at the para-position were well-tolerated in the KHMDS/glyme system. Halogen groups, such as chloro (1c), bromo (1d), and reactive iodo (1e) substitutions were also tolerated, resulting in the corresponding trifluoromethyl aryl

• yields (45–92%). Aryl substrates with a halogen attached at the meta- and ortho-positions were also accepted to furnish the desired products (2j–m) in good yields (66–82%). Moreover, di-substituted benzoate (1n), sterically demanding methyl adamantly carboxylate (1o), and conjugated methyl ester (1p

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• < T < −40 °C in the presence of aromatic nucleophiles, thiophenes 72-Cl and 72-Br could be converted into 74-Cl and 74-Br derivatives via a side-chain arylation reaction. When the reaction was conducted at −40 °C, the reactivity was shown to be governed by the nature of the halogen atom. For the

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• α-haloketones, is well known [36][37]. The halogen-mediated oxidation of 3-acyloxypyrroles and related compounds, to give α-hydroxy-3-ketopyrroles, is not reported but oxidations that represent equivalent reactivity have been reported [38][39][40][41]. The concept was tested in an NMR experiment in

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

• ] instead of carbon tetrachloride [22] furnished a close to quantitative yield of bromide 5a, though a prolonged reaction time of 72 h had to be accepted. The subsequent formation of boronate 6a was accomplished through a metal–halogen interchange with butyllithium and trapping with 2-isopropoxy-4,4,5,5

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• Subrata Nath Alexander Kappelt Matthias Spengler Bibhisan Roy Jens Voskuhl Michael Giese Organic Chemistry, University of Duisburg Essen, Universitätsstraße 7, 45141 Essen, Germany 10.3762/bjoc.17.13 Abstract The first example of halogen-bonded fluorescent liquid crystals based on the interaction

• of iodofluorobenzene derivatives with nitro-cyanostilbenes is reported. The systematic variation of the fluorination degree and pattern indicates the relevance of the halogen bond strength for the induction of liquid crystalline properties. The modular self-assembly approach enables the efficient

• tuning of the fluorescence behaviour and mesomorphic properties of the assemblies. Keywords: fluorescence; halogen bonding; liquid crystal; Introduction Supramolecular chemistry has proven to be an efficient approach for the development of novel smart materials, since it relies on non-covalent

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

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

• prepared stereoselectively from propargyl alcohol following the literature procedure, and the free hydroxy group was then protected as its TBDMS ether to produce 39 in 99% yield. The metal–halogen exchange of 39 followed by the Bu3SnCl quench in Et2O gave the desired stannane 40 in excellent yield (90

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• from the carbocupration of 85, a Grignard derivative of 1-heptyne [56]. After a lithium–halogen exchange, the corresponding vinyllithium was treated with p-menthane-3-carboxaldehyde to give the isomeric allylalcohols (−)-87a and (−)-87b in a 5:1 ratio. After chromatographic separation, (−)-adaline (1

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• helicenes with interesting electronic properties. Results and Discussion Synthesis In accordance with the above strategy, we first synthesized ortho-halogen alkynylazines 1a,b via the Sonogashira reaction of commercially available 2,3-dichloroquinoxaline and 2,3-dichloropyrazine with phenylacetylene using a

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

• Vyacheslav I. Supranovich,
• Igor A. Dmitriev and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

• involved in the reductive annelation reaction (Scheme 2). The process worked with nitrones containing alkyl, halogen, and electron-donating groups in the aromatic ring. With ester and cyano groups, the piperidines 3h and 3j were obtained in decreased yields, which may be tentatively attributed to a greater

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• ) gave the expected product 3c along with the dehydrated product 4c (Table 2, entry 3). Substrates containing a halogen, such as fluorine, chlorine, and bromine, were efficiently reacted to afford the products 3e–h in successively moderate yields (Table 2, entries 5–8). Notably, 3-fluorobenzaldehyde (2e

• clean process. A variety of aromatic aldehydes, including electron-donating, electron-withdrawing, as well as halogen groups was screened, affording the products in moderate to excellent yields. Azaarenes such as pyridines with various substitution patterns and a few quinolines were also reacted with

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• -dibromothienothiophene 2 [39], which was obtained from thieno[3,2-b]thiophene (1) [38], was triisopropylsilyl (TIPS)-protected by lithium-halogen exchange with n-BuLi and triisopropylsilyl chloride to give thienothiophene 3 in 69% yield. A halogen dance reaction of 3, induced by lithium diisopropylamide (LDA) at −78 °C

• , the SN4’-intermediate was directly alkylated with 2-ethylhexyl bromide and the corresponding dialkylated SN4' system was subsequently obtained by removal of the bromines by lithium–halogen exchange and acidic work-up [28]. Synthesis of S,N-heterotetracenes SN4''. In contrast to SN4’, S,N

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• process, an alkene reacts with a halogen cation to form a halonium ion, which immediately undergoes ring opening by fluoride to form a vicinal halofluoride (see Scheme 1). The overall result is an anti-addition of the XF moiety (X = Cl, Br, I) across the double bond. Since many nucleophilic fluorine

• the absence of the reagent. It is also worth mentioning that the bromolactone (rac)-17a was surprisingly stable against lactone ring-opening: the compound remained intact after 20 hours of reflux in methanol in the presence of a catalytic amount of H2SO4. Presumably, the halogen cation attacks from

• isomeric halofluorination products can be explained by the preferred formation of the halonium ions T6a–c, respectively, since the halogen cation attacks the C=C bond of the imide 19 from the less hindered side, followed by rearrangement into the intermediates (rac)-T7a–c, respectively. For epoxides and

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• . As a compromise, a 3-trimethylammoniumpropyl substituent was uniformly introduced at both imide positions (Figure 1). As shown previously by Würthner and co-workers, amine and halogen substituents at the NDI 2,6-positions have a remarkable effect on the NDI chromophore, as they endow the otherwise

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• to “neutral” (Me), electron-withdrawing (Cl, Br, CN) and electron-donating (MeO, OH) substituents as the desired imidazoles 3b/3b'–3h were isolated in 78–98% yield. The presence of additional halogen groups such as chlorine and bromine in 3c/3c' and 3d allows further downstream diversification by

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

• -accepting nitro group (2l) at the para position on the ring showed a good reactivity with ethyl acetoacetate (4) and urea (5) to afford the product 7g in an excellent isolated yield (94%, Table 6, entry 7). Halogen atoms at different positions on the ring of benzaldehyde derivatives (4-F: 2m, 4-Cl; 2n, and

• -withdrawing group (4-NO2: 2l), and halogen atoms (4-F: 2m, 4-Cl: 2n, and 3,4-difluoro: 2t), respectively, at different positions on the aromatic ring showed a good reactivity with the said reactants and afforded the corresponding products 11b–h that ranged from 90 to 96% (Table 7, entries 2–8). Further, the

• groups, such as electron-donating groups (4-Me: 2b, 4-OMe: 2e, and 3,4,5-trimethoxy: 2g), an electron-accepting group (4-NO2: 2l), and halogen atoms (4-F: 2m, 4-Cl: 2n, and 3-Br: 2s), respectively, at different positions on the aromatic ring displayed a good reactivity with malononitrile (8) and

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

• copper salt, acting as both, the catalyst for C–H activation and the oxidizing agent, was also required. The reaction occurred at higher temperatures (60 °C) compared to other dual catalytic systems. A wide variety of benzamide substrates bearing different functional groups such as alkyl, phenyl, halogen

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• ISC processes through intermolecular halogen bonding to generate efficient RTP was initially investigated by Kim et al. [58]. They developed the minimalistic 2,5-dihexyloxy-4-bromobenzaldehyde (1) [59][60][61][62][63] which showed a weak fluorescence in solution, but exhibited a green phosphorescence

• with a quantum yield of ΦP = 2.9% in the crystalline state: this behavior was caused by intermolecular halogen bonds from the carbonyl-oxygen atom to an adjacent bromine atom (Figure 1a). Despite multifarious examples of RTP in the crystalline state, purely organic compounds showing RTP in solution are

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• (Scheme 23) [59]. The authors rationalized the formation of 45 by considering that the inherent weakening of the C—X bond going down the halogen series may favor the generation of radical A with chloride and bromide derivatives, especially given the tertiary position of the halide and the stoichiometric

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• generally approached the subject. Specific potential functions are added to empirical force fields for hydrogen [87] or halogen [88] bonding. However, given that researchers have been busily defining additional non-covalent interactions such as tetrel [89], pnictogen [90] and chalcogen bonding [91], this

• approach leads to unnecessary complication of the model. As these interactions together with hydrogen and halogen bonding can all be treated within the single “σ-hole” framework [92], a single unified approach seems possible. However, such an approach would require a wave function or electron density

• interaction between halogens and nucleophiles as repulsive; whereas we now know that halogen-bonding attractions can be as strong as hydrogen bonds. There will be more such examples but it is important to identify the encompassing phenomenon, rather than defining a wealth of apparently unique interactions

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• , and trifluoromethyl they smoothly took part in the three-component reaction and provided the desired products 6ja–na in moderate yields. It is noteworthy that benzaldehydes containing a halogen atom such as fluorine, chlorine, bromine, and iodine in the para and meta-positions were also compatible

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• susceptibility of 2-chloro-N-phenethylacetamide (13), towards halogen exchange mediated by BTMS (Scheme 6). The reaction progress was monitored by 1H NMR spectroscopy monitoring the signals of the methylene groups C(O)CH2Cl in 13 vs C(O)CH2Br in the product 22 (see Figure S16 in Supporting Information File 1

• , CDCl3 (Table 3, entry 2, 42% conversion after 3 h) as well as lowering the temperature (Table 3, entry 3, rt, CDCl3, after 24 h 50% conversion into 22) slowed down the reaction. When TEA was added to the mixture, the halogen-exchange reaction slightly decreased (Table 3, entries 4 and 5). Remarkably

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

• phenyl as the residue R were selected as test cases for our proposed system. Over the last two decades, Knochel demonstrated the benefits of LiCl on the halogen–magnesium exchange rates [43] and on the organomagnesium solubility [44]. The most known example of this class is the isopropylmagnesium