Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• corresponding 2-aminochromene derivatives 22 and 37 in 92 and 82% yields respectively (Scheme 13) [26]. It is instructive to note that TBBDA is a versatile reagent in organic synthesis and has been reported to be efficient in oxidation of primary and secondary alcohols [27], in bromination of aromatic compounds

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• References Introduction As every student of organic chemistry knows, the early years of this branch of science were exciting and confusing at the same time. This is particularly true for the chemistry of aromatic compounds before Kekulé finally established the hexagonal structure for benzene [1]. Benzene was

• pyrolysis reaction (see Section 5). How fast a very large structural variety can be generated from these basic patterns, becomes obvious if one realizes that, for example, in the aromatic systems 12, the allene units can be anchored also in meta- and/or para-position and condensed aromatic compounds or

• ][111]. A shock-tube pyrolysis study of 2 in the temperature range of 540 to 1180 K at two nominal pressures (22 and 40 kbar) revealed that 2 plays an important role in the so-called propargyl mechanism, which is of importance in relation to the formation of aromatic compounds from nonaromatic

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence

• Akihito Hashidzume,
• Yongtai Zheng and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1312–1317, doi:10.3762/bjoc.8.150

• one to construct functional systems that convert photo energy based on molecular recognition. Among aromatic compounds, pyrene is the most examined as a fluorescence probe or label because it shows a relatively high fluorescence quantum yield and a relatively long fluorescence lifetime in both monomer

Synthesis and structure of tricarbonyl(η⁶-arene)chromium complexes of phenyl and benzyl D-glycopyranosides

• Thomas Ziegler and
• Ulrich Heber

Beilstein J. Org. Chem. 2012, 8, 1059–1070, doi:10.3762/bjoc.8.118

• transition-metal complexes of arenes have been prepared, characterized and described in the literature. Among the multitude of transition-metal complexes of aromatic compounds, however, only tricarbonyl(η6-arene)chromium compounds are widely used for organic syntheses [2][3][4]. This is due to the fact that

Dioxane dibromide mediated bromination of substituted coumarins under solvent-free conditions

• Subrata Kumar Chaudhuri,
• Sanchita Roy and
• Sanjay Bhar

Beilstein J. Org. Chem. 2012, 8, 323–329, doi:10.3762/bjoc.8.35

• aforesaid study [14]. We have also accomplished DD-mediated solvent-free regioselective electrophilic ring bromination of aromatic compounds [15]. Encouraged by the aforesaid literature precedence we envisaged the development of a solvent-free protocol for regioselective bromination of substituted coumarins

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• collected by using closed-loop stripping analysis (CLSA) and were analyzed by gas-chromatography–mass-spectrometry. A wide range of compounds was produced, although the absolute amount was small. Nevertheless, characteristic bouquets of compounds could be identified. Predominantly aromatic compounds and

• of the production of volatiles by M. tuberculosis can facilitate the rational design of alternative and faster diagnostic measures for tuberculosis. Keywords: aromatic compounds; CLSA; terpenes; tuberculosis; volatile profile; Introduction Tuberculosis (TB) remains one of the most threatening

• compounds are listed in Table 1. In addition to previously reported compounds 1–4 [9], several new volatiles were identified, predominantly aromatic compounds, such as 4-methylanisole (5), methyl salicylate (6), methyl 2-aminobenzoate (7), and methyl and ethyl benzoate (8 and 9), as well as fatty-acid

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

• , we turned our attention to compounds possessing a halogenmethylsulfonyl group. Aromatic compounds featuring this moiety has been reported to exhibit the desired biological activity [2][3][4][5][6][7]. The results of our previous research revealed that the presence of halogenmethylsulfonyl groups in

• some nitroaniline and benzimidazole derivatives was beneficial to their herbicidal and fungicidal activity [6][8][9]. Moreover, some 2-nitroaniline and 2,6-dinitroaniline derivatives belong to the group of commonly applied herbicides [10]. Herein we report the synthesis of novel aromatic compounds

Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

• Jeroen S. Dickschat,
• Hilke Bruns and
• Ramona Riclea

Beilstein J. Org. Chem. 2011, 7, 1697–1712, doi:10.3762/bjoc.7.200

• , alcohols, aldehydes, acyloins, nitrogen and oxygen heterocycles, aromatic compounds, and terpenoids. Carboxylic acids were dominating, and this class was composed of the branched isobutyric acid (49), isovaleric acid (50), and 2-methylbutyric acid (51) as the main compounds, with minor amounts of 5

• methyl esters were identified. The identification of these esters from their mass spectra and retention indices, as well as the verification of the proposed structures by synthesis of representative reference compounds is presented. Besides several other compounds, such as terpenes, pyrazines, aromatic

• compounds and methyl ketones, more than half of the components identified are unbranched and mono- and dimethylbranched FAMEs, many of this last group having not been reported before. Results and Discussion Volatiles from Micromonospora aurantiaca The volatiles released by agar plate cultures of the

Efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles from 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes

• Yiwen Yang,
• Chunxiang Kuang,
• Hui Jin,
• Qing Yang and
• Zhongkui Zhang

Beilstein J. Org. Chem. 2011, 7, 1656–1662, doi:10.3762/bjoc.7.195

• based on the condensation of hydrazines with 1,3-dicarbonyl compounds or their equivalents. However, the 1,3-dipolar cycloaddition offers a more convenient synthetic route. Sydnones are easily accessible aromatic compounds and versatile synthetic intermediates. They can be used as unusual, alternative

Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

• Charles Dylan Turner and
• Marco A. Ciufolini

Beilstein J. Org. Chem. 2011, 7, 1475–1485, doi:10.3762/bjoc.7.171

• revolutionized the business of producing elaborate aromatic compounds, both in the academic laboratory and in the industrial plant, and that continue to produce countless benefits to society in the form of new medicines and new materials. Structure of nothapodytine B. Structures of topopyrones. Structure and

Combined directed ortho-zincation and palladium-catalyzed strategies: Synthesis of 4,n-dimethoxy-substituted benzo[b]furans

• Verónica Guilarte,
• M. Pilar Castroviejo,
• Estela Álvarez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 1255–1260, doi:10.3762/bjoc.7.146

• , give rise to new and interesting dimethoxy-substituted benzo[b]furans. Keywords: benzo[b]furans; o-zincation; palladium; selectivity; Introduction The directed ortho-metallation (DoM) reaction has been widely used as a powerful and efficient method for regioselective functionalization of aromatic

• compounds and different directing groups have been used to facilitate the deprotonation reaction [1][2][3][4][5]. Various strong bases such as alkyl lithiums and their derivatives (for instance, TMEDA-activated complexes [6] and heavier alkali metal tert-butoxide-complexed alkyl lithium reagents, known as

Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation

• David R. Armstrong,
• Liam Balloch,
• Eva Hevia,
• Alan R. Kennedy,
• Robert E. Mulvey,
• Charles T. O'Hara and
• Stuart D. Robertson

Beilstein J. Org. Chem. 2011, 7, 1234–1248, doi:10.3762/bjoc.7.144

• -) metallation was favoured by direct sodium-mediated zincation. Keywords: alkali metal; crystal structure; isomerisation; metallation; zincation; Introduction While the metallation reaction remains an essential tool for constructing substituted aromatic compounds [1][2], the quest for new improved reagents

• direct zincation of functionalised arenes and heteroarenes [9][10]. However, common limitations have been noted for the use of this reagent with some electron poor and heterocyclic compounds which suffer from the drawback of limited regioselectivity, whilst several activated aromatic compounds bearing

A simple and convenient one-pot synthesis of substituted isoindolin-1-ones via lithiation, substitution and cyclization of N'-benzyl-N,N-dimethylureas

• Keith Smith,
• Gamal A. El-Hiti,
• Amany S. Hegazy and
• Benson Kariuki

Beilstein J. Org. Chem. 2011, 7, 1219–1227, doi:10.3762/bjoc.7.142

• result of our own interest in the use of lithium reagents in organic synthesis [55][56][57][58][59][60][61][62][63][64][65][66][67], we have had occasion to investigate lithiation of various aromatic compounds containing substituted amino groups. Factors that influence the site(s) of lithiation of such

Directed aromatic functionalization

• Victor Snieckus

Beilstein J. Org. Chem. 2011, 7, 1215–1218, doi:10.3762/bjoc.7.141

• find a fine assortment of forefront contributions in the field of manipulation and modification of aromatic compounds. Since it is a “moving” Series, my introductory comments required synchronization in order to adequately reflect the breadth of the contributions. A cornucopia of reports

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• be used in different subsequent reactions (Scheme 1). The first reaction studied was a Friedel–Crafts reaction of aromatic compounds. In comparison with the "cation pool" method, the "cation flow" method was far more successful for this reaction, producing the monoalkylated product 2 in 92% yield in

• the flow system [11]. Yoshida et al. also reported the electrochemical iodination of aromatic compounds by elemental iodine followed by a subsequent reaction with aromatic compounds. This sequential method has one main advantage over the batch method, in that the polyiodination problem for highly

• reactive aromatic compounds, based on disguised chemical selectivity, can be avoided by the micromixing of a solution of preformed iodine cations (I+) and a solution of an aromatic compound, increasing the yield of mono iodination product from 38% to 85% [12]. Nishiyama et al. reported the synthesis of

Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

• Kiymet Berkil Akar,
• Osman Cakmak,
• Orhan Büyükgüngör and
• Ertan Sahin

Beilstein J. Org. Chem. 2011, 7, 1036–1045, doi:10.3762/bjoc.7.118

• substitution; Introduction Our sustained interest in benzenoid aromatic compounds with high bromine content has led to the development of a regio- and stereoselective bromination method for aromatic compounds. Recently, we demonstrated the selective bromination of 9,10-dibromoanthracene (1) to give

Gold-catalyzed propargylic substitutions: Scope and synthetic developments

• Olivier Debleds,
• Eric Gayon,
• Emmanuel Vrancken and
• Jean-Marc Campagne

Beilstein J. Org. Chem. 2011, 7, 866–877, doi:10.3762/bjoc.7.99

• , allylsilanes, aromatic compounds and nitrogen nucleophiles. Interestingly, these reactions were not limited to monosubstituted propargylic alcohols [19][20][21][22]. In 2005, we described the direct Au(III)-catalyzed substitution of propargylic alcohols in the presence of various nucleophiles (allylsilanes

• , alcohols, thiols, electron rich aromatic compounds), and showed that gold probably acts as a Lewis acid to promote the formation of a stabilized propargylic carbocation intermediate [23][24]. A related reaction was subsequently reported by Dyker [25] in 2006, using azulene and 1,3-dimethoxybenzene in

• Scheme 16, the reaction proved restricted to alcohols and no reaction occurred with TsNH2 or electron-rich aromatic compounds such as 1,3-dimethoxybenzene. Some contradictions arose from these experiments. On one hand, when propargylic alcohols 1 and protected hydroxylamines were treated with gold

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• -polycyclic aromatic compounds has been developed utilizing charge migration [42][45]. For example, alcohol 155 reacts in superacid to give 5-methylbenzo[f]isoquinoline (158, Scheme 31) in good yield. This conversion involves formation of the 1,4-dication 156, which then undergoes charge migration to the 1,5

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• absorption (continuous line) and by RI (dashed line). The UV absorption of 6 in the GPC diagram (continuous line) clearly indicates the appearance of the aromatic compounds in a higher molecular weight area in comparison with the original polymer 4. The molecular weights of polymer 6 are about 18000 g mol−1

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• . The halogenation of SAlk-derivatives with subsequent replacement of the halogen atoms by fluorine. The introduction of SRF-moieties into aromatic compounds by both electrophilic and nucleophilic reagents. Various modes of perfluoroalkylation of organosulfur compounds including cationic, anionic

• aromatic compounds is shown in Scheme 32. The less reactive 2-Cl-5-NO2 benzonitrile forms the CF3S-derivative in only 49% yield after many hours reflux and 2-F-5-NO2 benzonitrile is a by-product despite the use of a 100% excess of thiophosgene. The use of Me4NF in place of KF for the generation of the CF3S

• is used widely to introduce functionality into aromatic compounds. However, early attempts using trifluoromethylthiosilver as the nucleophile were not encouraging [120] with yields below 30% accompanied with deaminated side products (up to 38%). The use of trifluoromethylthiocopper was rather

Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

• Nadine Schmeling,
• Roman Konietzny,
• Daniel Sieffert,
• Patrick Rölling and
• Claudia Staudt

Beilstein J. Org. Chem. 2010, 6, 789–800, doi:10.3762/bjoc.6.86

• industrial applications. Aromatics/aliphatics separation The separation of aromatics/aliphatics is receiving more and more attention, as the benzene content in gasoline is, by law in Europe, limited to less than 1%. Discussions on the reduction of toluene and polynuclear aromatic compounds in gasoline are

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

• electrophilic one [27]. This method opens up the possibility for the preparation of various reagents with electron-withdrawing substituents even in the para-position of aromatic compounds. The difluorosulfurane 26, obtained from the corresponding sulfide by treatment with xenon difluoride, was reacted first

Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

• Venkataramana Rajuri,
• Dariush Ajami,
• Gaston R. Schaller,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2010, 6, No. 30, doi:10.3762/bjoc.6.30

• carbon nanotubes which could eventually be extended in length by chemical vapor deposition [9][10]. This strategy could eventually open a way to prepare monodisperse nanotubes with well defined physical properties. Our approach to synthesize loop-like aromatic compounds is based on the Diels–Alder

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• as well as N,N-dimethylaniline were efficiently utilized as nucleophiles and the corresponding highly valuable optically active propargylated aromatic compounds 122 were isolated in moderate yield but with excellent enantioselectivities of up to 94% ee (Scheme 45) [97]. This milestone in the

Synthesis of 2,3,6,7-tetrabromoanthracene

• Christian Schäfer,
• Friederike Herrmann and
• Jochen Mattay

Beilstein J. Org. Chem. 2008, 4, No. 41, doi:10.3762/bjoc.4.41

• . Keywords: anthracene; arenes; cyclizations; polycycles; ring closure; 2,3,6,7-tetrabromoanthracene; Introduction Anthracene and its derivatives are long known polycyclic aromatic compounds showing a high potential for use in materials science (e.g. fluorescence probing, photochromic systems