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

On the functionalization of benzo[e][2,1]thiazine

• Kirill Popov,
• Tatyana Volovnenko and
• Julian Volovenko

Beilstein J. Org. Chem. 2009, 5, No. 42, doi:10.3762/bjoc.5.42

• Chloroaldehydes 1a,b are readily reduced under mild conditions by sodium borohydride to yield the alcohols 3a,b. Treatment of compounds 3a,b with thionyl chloride in dry benzene results in the formation of dichloro derivatives 4a,b, whilst the 3-bromomethyl derivatives 5a,b are obtained by refluxing 3a,b in

• concentrated hydrobromic acid. Nucleophilic substitution of the chlorine atoms in compounds 4 shows similar behaviour. Thus, treatment of the dichloro derivatives 4a,b with sodium methoxide gives a mixture of substitution products in a 2:1 isomer ratio with side-chain substitution predominating. The bromine

Gold film- catalysed benzannulation by Microwave- Assisted, Continuous Flow Organic Synthesis (MACOS)

• Gjergji Shore,
• Michael Tsimerman and
• Michael G. Organ

Beilstein J. Org. Chem. 2009, 5, No. 35, doi:10.3762/bjoc.5.35

• for deuterated chloroform (77.00 ppm). General procedure for the benzannulation reactions by MACOS A stock solution containing the acetylenic aldehyde (0.5 mmol, 1.0 equiv.) and alkyne (1.5 mmol, 3.0 equiv) in 0.7–0.8 mL 1,2-dichloro benzene (total mixture volume is 1.0 mL) was prepared and loaded

• into a Hamilton gastight syringe. The tubing was primed with 1,2-dichloro benzene and the syringe was connected to the reactor system with the aid of Microtight fittings after which it was placed in a Harvard 22 syringe pump that was set to deliver 20 μL/min. The single mode microwave was programmed to

Chemoselective reduction of aldehydes by ruthenium trichloride and resin- bound formates

• Basudeb Basu,
• Bablee Mandal,
• Sajal Das,
• Pralay Das and
• Ashis K. Nanda

Beilstein J. Org. Chem. 2008, 4, No. 53, doi:10.3762/bjoc.4.53

• ·3H2O), we carried out the CTH using a well-defined Ru(II) complex [Dichloro(p-cymene)ruthenium(II)] dimer; (2 mol%) under similar conditions and indeed a comparable result was observed (Table 1, entry 11). On the basis of this comparison, it may be presumed that the Ru(III) salt might undergo in situ

Synthesis of methylenebisamides using CC- or DCMT- activated DMSO

• Qiang Wang,
• Lili Sun,
• Yu Jiang and
• Chunbao Li

Beilstein J. Org. Chem. 2008, 4, No. 51, doi:10.3762/bjoc.4.51

• , when amides react with electrophile-activated DMSO, the yields are rather low. We have found new electrophiles, 2,4,6-trichloro[1,3,5]triazine (CC) and 2,4-dichloro-6-methoxy[1,3,5]triazine (DCMT), which activate DMSO in the presence of amides to yield methylenebisamides in good to fair yields. The

• drastic reaction conditions [19][22]. In this paper, we report the reaction of amides with DMSO activated by CC or 2,4-dichloro-6-methoxy[1,3,5]triazine (DCMT) [24]. Results and Discussion Initially, we chose CC as the activation reagent and benzamide as a model substrate to optimize the reaction

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• and α-epoxyketones have also occurred thermally or photochemically by the presence of various electron acceptors. These reactions have been observed thermally by ceric ammonium nitrate (CAN), [28][29] 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) [30] and iron(III) chloride [31] or photo-induced

New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline- 2,4(1H,3H)-dione compounds

• Oldřich Paleta,
• Karel Pomeisl,
• Stanislav Kafka,
• Antonín Klásek and
• Vladislav Kubelka

Beilstein J. Org. Chem. 2005, 1, No. 17, doi:10.1186/1860-5397-1-17

• , amides or acyl halides. [5][6] Examples of the successful Perkow reaction also include chlorofluoro ketones, e.g. 1,3-dichloro-1,1,3,3-tetrafluoroacetone,[7] α-halonitroalkanes, and in rare cases also polycyclic compounds[8] such as 3,3-dichloro-1-methylquinoline-2,4(1H,3H)-dione. [9] In the Perkow