Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

• Han Wang,
• Kun Wen,
• Nurbiya Nurahmat,
• Yan Shao,
• He Zhang,
• Chao Wei,
• Ya Li,
• Yongjia Shen and
• Zhihua Sun

Beilstein J. Org. Chem. 2012, 8, 744–748, doi:10.3762/bjoc.8.84

• . Instead, many procedures still opted for the chlorination of protected aniline derivatives or the introduction of nitrogen (for example, through nitration) to chlorobenzenes. Part of the reason could be that the procedure with CuCl2 is carried out in concentrated aqueous HCl and requires the flow of both

Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0]nonadiene

• Sabine Leber,
• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2012, 8, 738–743, doi:10.3762/bjoc.8.83

• with 3-bromopropanol followed by nitration of the resulting diol 6 (Scheme 2). The isomeric 1,2,3-trisubstituted aromatic 10 was obtained by etherification of nitroresorcinol (Scheme 3). The two diols 7 and 10 reacted readily with the diacid dichloride 3 in boiling toluene in the presence of

Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

• Karel Křenek,
• Petr Šimon,
• Lenka Weignerová,
• Barbora Fliedrová,
• Marek Kuzma and
• Vladimír Křen

Beilstein J. Org. Chem. 2012, 8, 428–432, doi:10.3762/bjoc.8.48

• , Czech Republic 10.3762/bjoc.8.48 Abstract The synthetic procedures for a large-scale preparation of o- and p-nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranoside are described. The synthetic pathway employs the glycosylation of phenol with ManNAc oxazoline, followed by nitration of the aromatic moiety

Derivatives of phenyl tribromomethyl sulfone as novel compounds with potential pesticidal activity

• Krzysztof M. Borys,
• Maciej D. Korzyński and
• Zbigniew Ochal

Beilstein J. Org. Chem. 2012, 8, 259–265, doi:10.3762/bjoc.8.27

• tribromomethyl phenyl sulfone derivatives as novel potential pesticides is reported. The title sulfone was obtained by following three different synthetic routes, starting from 4-chlorothiophenol or 4-halogenphenyl methyl sulfone. Products of its subsequent nitration were subjected to the SNAr reactions with

• was its nitration, carried out by standard means of a mixture of concentrated nitric and sulfuric acids (Scheme 3) [12]. As pesticides are chemicals produced most commonly in considerable quantities, optimization of the synthetic process is highly desirable. Bearing in mind that the obtained nitro

• compound is the key intermediate for all further transformations, we decided to check whether the use of bromine-substituted aromatic methylsulfone 4' would prove to offer higher yields in the halogenation/nitration sequence. Bromination of 4' with BrCl afforded tribromomethyl sulfone 1' in 90% yield

Synthetic approaches to multifunctional indenes

• Neus Mesquida,
• Sara López-Pérez,
• Immaculada Dinarès and
• Ermitas Alcalde

Beilstein J. Org. Chem. 2011, 7, 1739–1744, doi:10.3762/bjoc.7.204

• 6 or 13 and the lithium salt of N-acetylpiperidine or N-acetylpyrrolidine afforded indenylacetamides 17–19 in good yield (≥67%). Finally, to broaden the scope of this aldol-type reaction, we examined the synthesis of (1,1-dimethyl-3-indenyl)acetamides. Following a standard nitration protocol applied

• marked improvement on a previously reported 62% yield of nitroindanone 21 employing a different nitration method [28]. In our recently reported preliminary experiments, the conversion of 21 to the corresponding (3-indenyl)acetic acid 22 resulted in a fairly low yield of 27%, and the transformation to N,N

Synthesis and oxidation of some azole-containing thioethers

• Andrei S. Potapov,
• Nina P. Chernova,
• Vladimir D. Ogorodnikov,
• Tatiana V. Petrenko and
• Andrei I. Khlebnikov

Beilstein J. Org. Chem. 2011, 7, 1526–1532, doi:10.3762/bjoc.7.179

• unreactive compound 5. The reactivity of pyrazole-containing thioether 3 in aromatic electrophilic substitution was evaluated by using nitration and iodination reactions as examples. Nitration of compound 3, by 68% nitric acid in concentrated sulfuric acid, results in both substitution in the heterocyclic

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• esomeprazole the subsequent steps involve an S-alkylation as well as an asymmetric oxidation of the newly formed thioether [59][60]. Additional structural diversity in the aniline component can be introduced by protection, nitration, deprotection and reduction of the starting amine compound 201. Scheme 40 for

• utilised acid catalysed rearrangement of methyl N-nitroanthranilate (212) which is obtained by N-nitration of methyl anthranilate (211, Scheme 42). Alkylation of the intermediate with the biphenylmethyl bromide 208 under mildly basic conditions yields adduct 213. Upon treatment of this compound with 80

Tribenzotriquinacenes bearing three peripheral or bridgehead urea groups stretched into the 3-D space

• Jörg Tellenbröker and
• Dietmar Kuck

Beilstein J. Org. Chem. 2011, 7, 329–337, doi:10.3762/bjoc.7.43

• Discussion As shown earlier, introduction of six amino groups at the periphery of the TBTQ skeleton is achievable by nitration with nitric acid (100%) and sulfuric acid (98%) followed by reduction [20]. However, this holds true only for TBTQ derivatives with alkyl groups at the benzhydrylic bridgehead

• positions, such as the tetramethyl derivative 3 [20] and the related tripropyl analog 4 [5][7]. The monomethyl derivative 2 decomposes under these conditions. By contrast, threefold nitration of the arene periphery, leading to single functionalization at the outer positions of each of the three benzene

• also successfully applied to the analogous nitration of compound 2 [22]. Our attempts to separate the two constitutional isomers 8 and 9 by gravity column chromatography failed due to their almost identical elution behaviour. However, 1H NMR spectroscopy of the mixture allowed us to determine the ratio

A surprising new route to 4-nitro-3-phenylisoxazole

• Henning Hopf,
• Aboul-fetouh E. Mourad and
• Peter G. Jones

Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68

• include the reaction of aromatic α,β-unsaturated aldehydes with dinitrogen trioxide [11][12], the nitration of 3-phenyl-isoxazole [13][14], and the hydrolysis of methyl 4-nitro-3-phenyl-5-carboxylate, obtained by reaction of α-nitroacetophenone oxime and methoxalyl chloride [15]. In conclusion, a very

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• synthesized sulfonated analogs of (trifluoromethyl)dibenzochalcogenium salts by sulfonation with fuming sulfuric acid. Further nitration of sulfonate 14 led to a more reactive nitro-substituted derivative 15 (Scheme 10). These reagents allow easy separation of by-products from the desired trifluoromethylated

• introduced in the meta-position of the benzene ring by a conventional nitration reaction. Shreeve and co-workers used these reagents for the trifluoromethylation of aromatic systems [24]. After optimization of reaction conditions, they found that the best result for the trifluoromethylation of aniline with

• first electrophilic trifluoromethylating reagent and its reaction with a thiophenolate. Synthetic routes to S-CF3 and Se-CF3 dibenzochalcogenium salts. Synthesis of (trifluoromethyl)dibenzotellurophenium salts. Nitration of (trifluoromethyl)dibenzochalcogenium salts. Synthesis of a sulphonium salt with

Efficient and improved synthesis of Telmisartan

• A. Sanjeev Kumar,
• Samir Ghosh and
• G. N. Mehta

Beilstein J. Org. Chem. 2010, 6, No. 25, doi:10.3762/bjoc.6.25

• -per-day dosage. The first total synthesis of Telmisartan as introduced by Ries et al. (Scheme 1) starts with the acylation of 4-amino-3-methylbenzoic acid methyl ester (2) with butyryl chloride, followed by nitration, reduction of the nitro group, and subsequent cyclization of the resulting amine to

Dipyridodiazepinone derivatives; synthesis and anti HIV-1 activity

• Nisachon Khunnawutmanotham,
• Nitirat Chimnoi,
• Arunee Thitithanyanont,
• Patchreenart Saparpakorn,
• Kiattawee Choowongkomon,
• Pornpan Pungpo,
• Supa Hannongbua and
• Supanna Techasakul

Beilstein J. Org. Chem. 2009, 5, No. 36, doi:10.3762/bjoc.5.36

• , followed by chloro displacement from the resulting 2-chloro compound with the aminocyclopropyl group, and finally reducing the nitro to the amino group. 2-Chloro-5-nitronicotinic acid (30) was prepared by nitration of commercially available 2-hydroxynicotinic acid (28) followed by treatment with POCl3

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• relationship between the substituents of the pyrrolidine was restored to give the more stable isomer 179. The quinone ring was then elaborated by aromatic nitration of compound 179, reduction to the aniline and subsequent treatment with Fremy’s salt to give compound 180. No further developments were made on

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• electron withdrawing behavior to the alkoxy group but also acts to deactivate the aromatic ring system [53]. Electrophilic Aromatic Substitution Trifluoromethoxybenzene, for example, undergoes nitration considerably (up to 5 times) more slowly than benzene. The electrophilic substitution occurs selectively

• chloro and bromo substituents. The trifluoromethoxy substituent has a pronounced preference for the para substitution. Unless the para position is occupied, ortho isomers are formed only in small amounts (≤ 10%) without any trace amounts of the meta isomers [52][63][64]. When nitration is carried out

• under standard conditions, the ortho/para ratio changes with the number of fluorine atoms as depicted in Scheme 10 [52][65][66]. At temperatures in the range of 25 – 50 °C, double nitration can be achieved. The resulting 2,4-dinitrophenyl ethers are isolated in moderate to excellent yield [29][66][67

Single and double stereoselective fluorination of (E)-allylsilanes

• Marcin Sawicki,
• Angela Kwok,
• Matthew Tredwell and
• Véronique Gouverneur

Beilstein J. Org. Chem. 2007, 3, No. 34, doi:10.1186/1860-5397-3-34

• assignment of compounds 2a-i was assigned by analogy with the nitration of identical (E)-allylsilanes as reported by Panek. [22][23][24][25][26][27] This chemistry offers the unique opportunity to access alkenes flanked with two allylic and stereogenic fluorinated centres upon double electrophilic