The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

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

• the product, has also been employed for the preparation of the parent hydrocarbon 2 (Scheme 6). The reduction of 1,6-dichloro-2,4-butadiyne (43) in methanol with a zinc/copper couple furnished the bisallene 2, but also provided at least three other C6H6-isomers, 44–46, requiring extensive

• below). An early reference to the preparation of 3,4-dichloro-1,2,4,5-hexatetraene by Carothers and Coffman requires reinvestigation with modern spectroscopic methods [46][47]. If confirmed, it would not only describe the first preparation of a functionalized bisallene, but also the first representative

• product (Scheme 41), the reaction of 24 with either dichloro (170: R = Cl) or diphenylketene (170, R = phenyl) furnished largely the [2 + 2] cycloadducts 171. Only traces of the Diels–Alder adduct 172 are observed in this case. This example seems to be the only one in which the [2 + 4] and [2 + 2

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• (4) was synthesized following a procedure described in [32]. Diethyl 2-vinyl-1,1-cyclopropanedicarboxylate could be obtained according to [33] from sodium ethoxide, diethyl malonate and trans-1,4-dichloro-2-butene in ethanol (Scheme 2). The desired macromonomer 5 was prepared in two steps according

Organocatalytic asymmetric Michael addition of unprotected 3-substituted oxindoles to 1,4-naphthoquinone

• Jin-Sheng Yu,
• Feng Zhou,
• Yun-Lin Liu and
• Jian Zhou

Beilstein J. Org. Chem. 2012, 8, 1360–1365, doi:10.3762/bjoc.8.157

• details, see Supporting Information File 1). Other quinones such as 2,6-dichloro-1,4-benzoquinone and 1,4-benzoquinone were also examined, however, none of them could react with 3-phenyloxindole 1a to give the desired product. While the oxidation product 3 was obtained as the only product from the Michael

Identification and isolation of insecticidal oxazoles from Pseudomonas spp.

• Florian Grundmann,
• Veronika Dill,
• Andrea Dowling,
• Aunchalee Thanwisai,
• Edna Bode,
• Narisara Chantratita,
• Richard ffrench-Constant and
• Helge B. Bode

Beilstein J. Org. Chem. 2012, 8, 749–752, doi:10.3762/bjoc.8.85

• and 8 were synthesized. Briefly, the respective tryptamine derivatives were formed, which were then oxidized at the alpha-position with the help of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and cyclized to give the oxazoles by using phosphorylchloride as described [9]. Additionally, three

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• , phenylsulfur pentafluoride was prepared by reaction of 1,4-bis(acetoxy)-2-cyclohexene with SF5Br under 250 W sunlamp irradiation, followed by dehydrobromination and then aromatization reactions [36]. A triethylborane-catalyzed reaction of 4,5-dichloro-1-cyclohexene with SF5Cl followed by dehydrochlorination

Organic synthesis using (diacetoxyiodo)benzene (DIB): Unexpected and novel oxidation of 3-oxo-butanamides to 2,2-dihalo-N-phenylacetamides

• Wei-Bing Liu,
• Cui Chen,
• Qing Zhang and
• Zhi-Bo Zhu

Beilstein J. Org. Chem. 2012, 8, 344–348, doi:10.3762/bjoc.8.38

• obtained, but 2,2-dichloro-N-phenylacetamide was provided as the major product, upon addition of Lewis acids such as FeCl3, ZnCl2 and CuCl2 in the reaction system. Based on this result, we developed a simple and efficient approach to the synthesis of 2,2-dihalo-N-phenylacetamides, on which we report herein

• application of this protocol to synthesize difunctionalized acetamides from 3-oxo-butanamides is reported here for the first time. In order to probe the mechanism of this transformation, we employed 2,2-dichloro-3-oxo-N-phenylbutanamide (1m) and 2,2-dibromo-3-oxo-N-phenylbutanamide (1n) as reactants under

• acidic conditions in the presence of Zn(OAc)2 (Scheme 5), and we found that the reaction can also give the corresponding product 2,2-dichloro-N-phenylacetamide (2a) and 2,2-dibromo-N-phenylacetamide (3a). On the basis of these preliminary results, a mechanistic proposal for this transformation

Double N-arylation reaction of polyhalogenated 4,4’-bipyridines. Expedious synthesis of functionalized 2,7-diazacarbazoles

• Mohamed Abboud,
• Emmanuel Aubert and
• Victor Mamane

Beilstein J. Org. Chem. 2012, 8, 253–258, doi:10.3762/bjoc.8.26

• -diazacarbazole by using a palladium-catalyzed double N-arylation of 4,4’-dichloro-3,3’-bipyridine, itself obtained after a long reaction sequence [25][26][27]. In another patent, an intramolecular Buchwald–Hartwig amination [28][29] was used to generate a 2,7-diazacarbazole derivative in low yield [30]. Recently

• micrOTOFQ. All reagents were used as received. TLC was performed on silica gel plates and visualized with an UV lamp (254 nm). Chromatography was performed on silica gel (70–230 mesh). General procedure for the preparation of 3,6-dichloro-9-aryl-2,7-diazacarbazole 3a–g. Argon was bubbled into a mixture of

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

• Sonja Findeisen-Tandel,
• Wolfgang Weissflog,
• Ute Baumeister,
• Gerhard Pelzl,
• H. N. Shreenivasa Murthy and
• Channabasaveshwar V. Yelamaggad

Beilstein J. Org. Chem. 2012, 8, 129–154, doi:10.3762/bjoc.8.15

• increase amounts to 69 K for the laterally nonsubstituted compounds H 4a/OH 4a, but is reduced to 33 K for 4,6-dichloro-substituted compounds (see Supporting Information File 1, Table S4). The 4-bromoresorcinol derivative OH 4b (Z = 4-Br) is isomeric to the 4-bromoisophthalic acid ester OH 3b. The texture

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• further encodes a halogenase/ACP didomain protein that is suggested to be responsible for the gem-dichloro group in hectochlorin, HctB. The specifities of the NRPS adenylation domains have been confirmed in vitro [47]. Lyngbyatoxin Lyngbyatoxins 11, produced by Lyngbya majuscula, can cause skin

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• modified, hyperbranched polyethylenimine (PEI-CD) was investigated. 5,8-Dichloro-1,4-dihydroxyanthraquinone (AQ-OH) was enclosed simply by ionic attraction between the phenolate groups of AQ-OH and the protonated amino groups of polyethylenimine (PEI). Additionally, the adamantyl moieties of 1,4-bis-N

• heating [25]. For optical visualization of the attachment and release of suitable molecules, two anthraquinone dyes were chosen as model compounds in the present work [26]. Results and Discussion 5,8-Dichloro-1,4-dihydroxyanthraquinone (1) and 1,4-bis-N-adamantylaminoanthraquinone (2) were used as model

• released separately or simultaneous in response to different external stimuli. Conclusion The controlled release of different dyes from a drug delivery system based on hyperbranched polyethylenimine was investigated. The ionic interactions between the PEI scaffold and the hydroxy moieties of 5,8-dichloro

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• ethers and alkenes (MOM = methoxymethyl, Scheme 25) [90]. The activation of these allenes by the dichloro(pyridine-2-carboxylato)Au(III) complex Au7 generates an oxocarbenium intermediate XXVII, which undergoes the (3 + 2) annulation with the alkene. The resulting bicyclo[3.1.0] species XXVIII, related

Multicomponent reaction access to complex quinolines via oxidation of the Povarov adducts

• Esther Vicente-García,
• Rosario Ramón,
• Sara Preciado and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2011, 7, 980–987, doi:10.3762/bjoc.7.110

• aromatic species. The literature contains scattered reports of the use of oxidants for this transformation: 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), ceric ammonium nitrate (CAN), nitrobenzene, elemental sulfur, palladium and manganese dioxide among others, all of them far from being ideally suited

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

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• -trichlorophenyl)pyrazole III has been reported as a potent corticotrophin-releasing factor-1 (CRF-1) receptor antagonist [9]. 5-Amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-(3-methoxyphenyl)-3-methylthiopyrazole IV has been described as a potent GABA inhibitor with selectivity towards insect versus

• into 5-amino-1-aryl-4-diethoxyphosphoryl-3-halomethylpyrazoles 110. 2,6-Dichloro-4-trifluoromethylphenylhydrazine undergoes this reaction under more drastic conditions, i.e., prolonged refluxing (16–20 h) in carbon tetrachloride (Scheme 31) [73]. Heterocyclization reactions of trifluoromethylcyanovinyl

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• (DMT) and 1,3-dimethyluracil (DMU) with benzophenone (1b) and some 4,4’-disubstituted derivatives (dimethoxy (1a), difluoro (1c), dichloro (1d), dibromo (1e) and dicyano benzophenone (1f)) that gives rise to two regioisomeric oxetanes, 2 and 3. The regioselectivity (the ratio of 2/3) decreased

Synthesis of Ru alkylidene complexes

• Renat Kadyrov and
• Anna Rosiak

Beilstein J. Org. Chem. 2011, 7, 104–110, doi:10.3762/bjoc.7.14

• -Diazabicyclo[5.4.0]undec-7-ene (3.3 mL, 22 mmol) and tricyclohexylphosphine (6.17 g, 22 mmol) were added under an argon atmosphere to a suspension of dichloro(1,5-cyclooctadiene)ruthenium(II) (2.8 g, 10 mmol) in isopropanol (100 mL). The resulting mixture was heated at reflux for 2 h. THF (150 mL) was added to

• dichloro(1,5-cyclooctadiene)ruthenium(II) (660 mg, 2.35 mmol) in isopropanol (20 mL). The mixture was heated at reflux under an argon atmosphere for 1 h. Toluene (24 mL) was added to the resulting brick-red suspension and the mixture heated for further 30 min at reflux and then allowed to cool to 5–10 °C

• -7-ene (0.75 mL, 52 mmol) and 20% solution of tricyclohexylphosphine in toluene (7.7 mL, 5.9 mmol) were added under an argon atmosphere to a suspension of dichloro(1,5-cyclooctadiene)ruthenium(II) (660 mg, 2.35 mmol) in isopropanol (20 mL). The mixture was then heated at reflux under an argon

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• complex [RuCl2(=CHPh)(SIMes)(PCy3)], CuCl, and dHbipy (SIMes is 1,3-dimesitylimidazolin-2-ylidene, dHbipy is 4,4'-di-n-heptyl-2,2'-bipyridine) was able to promote the ATRA of trichloroacetic acid onto cyclopentadiene followed by a lactonization into 3,3-dichloro-3,3a,4,6a-tetrahydro-2H-cyclopenta[b]furan

• -2-one (18). These results prompted us to examine the cascade RCM/decomposition/ATRA/lactonization of substrate 16 into dichloro compound 18 with homobimetallic complex 1 under mild thermolysis conditions. Thus, the substrate and the catalyst precursor (5 mol %) were dissolved in toluene and heated

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• initiators available, we focused this study on the application of the less investigated indenylidene Ru-based catalysts: (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene) dichloro-(3-phenyl-1H-inden-1-ylidene)(tricyclohexylphosphine) ruthenium(II) (C1), (1,3-bis(2,4,6-trimethylphenyl)-2

• -imidazolidinylidene)dichloro-(3-phenyl-1H-inden-1-ylidene)(pyridyl) ruthenium(II) (C2) and the newly developed “boomerang” complex (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(2-(1-methylacetoxy)phenyl)methylene ruthenium(II) (C3) [31] (Figure 2). These indenylidene Ru-complexes provide an

• -trimethylphenyl)-2-imidazolidinylidene) dichloro-(3-phenyl-1H-inden-1-ylidene)(tricyclohexylphosphine) ruthenium(II) (Umicore, C1), (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro-(3-phenyl-1H-inden-1-ylidene) (pyridyl) ruthenium(II) (Umicore, C2), (1,3-bis(2,4,6-trimethylphenyl)-2

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127

• , complexes 33a, e, f, g were irradiated at 365 nm in the presence of RCM and ROMP substrates [78]. A summary of the results is presented in Table 4 and Table 5. The discovery that light irradiation induces photoisomerisation of the cis-dichloro complexes led to the proposed mechanism shown in Scheme 7. Thus

• , photoactivation of sulfur-chelated ruthenium benzylidene complexes was found to depend on the generation of the active trans-dichloro isomer via 14-electron intermediates. The design of a photoswitchable system was based on the fact that the latent isomer (cis-dichloro) was thermodynamically more stable than its

• active counterpart (trans-dichloro). Thus, illumination with UV light generates an active isomer, but a short heating period regenerates the inactive isomer. The switchable nature of the system was demonstrated by 15 min irradiation of a tetrachloroethane solution of diethyldiallyl malonate with 5 mol

Halide exchanged Hoveyda-type complexes in olefin metathesis

• Julia Wappel,
• César A. Urbina-Blanco,
• Mudassar Abbas,
• Jörg H. Albering,
• Robert Saf,
• Steven P. Nolan and
• Christian Slugovc

Beilstein J. Org. Chem. 2010, 6, 1091–1098, doi:10.3762/bjoc.6.125

• . Complexes 2 and 3 were prepared by addition of excess potassium bromide (KBr) or potassium iodide (KI) to a suspension of 1 in methanol, following the procedures for similar transformations of different dichloro carbene complexes to their diiodo analogues [26]. In these cases THF [15][26] or acetone [27

• ) (Table 2, Entry 1 and 7), while polymers prepared with M31 (ki/kp ≈ 10–1000) are typically characterised by low Mn values and low PDIs [24] (Table 2, Entry 2 and 8). Polymerisations initiated with the dichloro derivative 1 yield polymers with relatively low Mn and fairly narrow molecular weight

• catalyzing transformations of sterically hindered substances. The parent dichloro derivative 1 is the most active catalyst in every transformation studied. The diiodo derivative 3 is a slightly inferior catalyst in RCM, enyne metathesis and CM, but 3 is reluctant or even ineffective to initiate ROMP of

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• experimentation, it became clear that ethylene gas was crucial for driving this reaction forward (compare entry 4 with 7, Table 1) [21]. 2,6-Dichloro-1,4-benzoquinone, which has been reported to prevent isomerization [22], gave disappointing results (entry 8, Table 1). When our optimized conditions were applied

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

• Latif Kelebekli,
• Yunus Kara and
• Murat Celik

Beilstein J. Org. Chem. 2010, 6, No. 15, doi:10.3762/bjoc.6.15

• groups in aminocyclitol 18 [25] attached to the six-membered ring resembles the configuration of conduramine D-2 [36][37][38]. Hydrolysis of the acetate groups with H2SO4 proceeded smoothly to deliver aminocyclitol 6 in 84% yield. For the synthesis of dichloro derivative, we replaced the acetoxy groups

• palladium-catalyzed ionization/cyclization reaction. Synthesis of aminocyclitol analogue 6. Synthesis of oxazolidone 23. Mechanism of the palladium-catalyzed ionization/cyclization reaction in dichloro biscarbamate 22. Synthesis of dichloroaminocyclitol 7. Supporting Information Supporting Information File

Functional properties of metallomesogens modulated by molecular and supramolecular exotic arrangements

• Alessandra Crispini,
• Mauro Ghedini and
• Daniela Pucci

Beilstein J. Org. Chem. 2009, 5, No. 54, doi:10.3762/bjoc.5.54

• introducing of further aromatic rings equipped with several aliphatic tails each. Hence the synthesis of a series of cis-dichloro hexacatenar Zn(II) complexes has been performed (Figure 5) [56]. In this case the molecular organization in the mesophase, mainly driven by intermolecular attractive interactions

Palladium- catalyzed cross coupling reactions of 4-bromo- 6H-1,2-oxazines

• Reinhold Zimmer,
• Elmar Schmidt,
• Michal Andrä,
• Marcel-Antoine Duhs,
• Igor Linder and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2009, 5, No. 44, doi:10.3762/bjoc.5.44

• furnishing 4,5-dichloro-substituted compound 7a as a by-product in 13% yield. With the 4-halogenated 6H-1,2-oxazines 2 and 6 in hand, palladium-catalyzed cross couplings offer an efficient and useful approach for the synthesis of novel functionalized 6H-1,2-oxazines. The Suzuki-coupling of the 4-bromo