- Expanding the Family of Hoveyda-Grubbs Catalysts Containing Unsymmetrical NHC Ligands
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A series of Hoveyda-Grubbs second-generation catalysts containing N-alkyl/N′-aryl N-heterocyclic carbene (NHC) ligands were synthesized and investigated in representative olefin metathesis reactions. Steric perturbations of unsymmetrical NHCs were achieved through modulation of the hindrance of alkyl (neopentyl, neophyl, cyclohexyl) and aryl (2-isopropylphenyl, mesityl) substituents at the nitrogen atoms in combination with different backbone configurations (syn and anti). The NHC substitution patterns strongly influence the stability and reactivity of the corresponding complexes. In general, complexes bearing an anti NHC backbone are more stable and more active than their corresponding syn isomers. In both the series, the presence of bulky, highly branched N-alkyl groups tends to give reduced catalytic differences between syn and anti isomers, whereas the nature of the N′-aryl substituent (2-isopropylphenyl or mesityl) gives rise to different activity and/or selectivity. Of note, an N′-mesityl catalyst with anti backbone was found to be highly competent in the ethenolysis of ethyl oleate, achieving up to 90% selectivity for the formation of terminal olefins.
- Paradiso, Veronica,Bertolasi, Valerio,Costabile, Chiara,Caruso, Tonino,D?browski, Micha?,Grela, Karol,Grisi, Fabia
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- Mixed isobutylphobane/n-heterocyclic carbene ruthenium- Indenylidene complexes: Synthesis and catalytic evaluation in olefin metathesis reactions
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Two new second generation ruthenium(II) dichloride-indenylidene complexes [RuCl2(9- isobutylphosphabicyclo [3.3.1]nonane) (NHC)(3-phen- yl-1-indenylidene)], where NHC=1,3-bis(2,4,6-trimethylphenyl) imidazolin-2-ylidene (SIMes) or its unsaturated imidazol-2-ylidene analogue (IMes), were isolated in high yields upon heating a tetrahydrofuran (THF) solution of the diphosphane complex [RuCl2(isobutylphobane) 2(3-phenyl-1-indenylidene)]with a two-fold excess of the corresponding imidazol- (in)ium-2-carboxylate zwitterions. Both products were characterized by 1H, 13C, and 31P NMR spectroscopy, and the molecular structure of [RuCl2(isobutylphobane) (SIMes)(3-phenyl-1-indenylidene)]was determined by X-ray diffraction analysis. A close inspection of the packing structure revealed the presence of different types of intra- and intermolecular interactions that enhanced the global stability of the crystals, while low temperature NMR experiments showed the existence of two distinct rotational isomers due to the unsymmetrical nature of the phobane ligand. The catalytic activity of both compounds was assessed in olefin metathesis using benchmark ring-opening metathesis polymerization, ring-closing metathesis (RCM), and cross-metathesis reactions, and compared with those of related first and second generation ruthenium-benzylidene and indenylidene catalyst precursors. Kinetic studies confirmed the high thermal stability of the mixed isobutylphobane/ N-heterocyclic carbene complexes, which suffered from a slow initiation efficiency compared to other catalytic systems based on the tricyclohexylphosphane ligand. However, the remarkable robustness of [RuCl2(isobutylphobane) (SIMes)(3-phenyl-1- indenylidene)]was beneficial for performing the RCM of diethyl 2,2-bis(2-methylallyl)malonate. Monitoring the formation of the ruthenium-methylidene active species [RuCl 2(isobutylphobane)- (SIMes) (=CH2)]derived from this precursor further demonstrated its ability to sustain long reaction times and high temperatures required to carry out the RCM of tetrasubstituted olefins.
- Sauvage, Xavier,Zaragoza, Guillermo,Demonceau, Albert,Delaude, Lionel
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- Enantioselective Synthesis of Functionalized Arenes by Nickel-Catalyzed Site-Selective Hydroarylation of 1,3-Dienes with Aryl Boronates
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A catalytic method for the site-selective and enantioselective synthesis of functionalized arenes by the intermolecular hydroarylation of terminal and internal 1,3-dienes with aryl pinacolato boronates is reported. The reactions are promoted by 5.0 mol %
- Marcum, Justin S.,Meek, Simon J.,Taylor, Tiffany R.
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supporting information
p. 14070 - 14075
(2020/06/10)
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- Selective α,δ-hydrocarboxylation of conjugated dienes utilizing CO2and electrosynthesis
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To date the majority of diene carboxylation processes afford the α,δ-dicarboxylated product, the selective mono-carboxylation of dienes is a significant challenge and the major product reported under transition metal catalysis arises from carboxylation at the α-carbon. Herein we report a new electrosynthetic approach, that does not rely on a sacrificial electrode, the reported method allows unprecedented direct access to carboxylic acids derived from dienes at the δ-position. In addition, the α,δ-dicarboxylic acid or the α,δ-reduced alkene can be easily accessed by simple modification of the reaction conditions. This journal is
- Buckley, Benjamin R.,Elmorsy, Saad S.,Malkov, Andrei V.,Mashaly, Mohammad A.,Said, Samy B.,Sheta, Ahmed M.
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p. 9109 - 9114
(2020/09/17)
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- Preparation method of phenylacetaldehyde
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The invention discloses a preparation method of phenylacetaldehyde. The method comprises the following steps: taking 1, 4-diphenyl-2-butyne as a raw material, performing Lindelar catalytic hydrogenation reaction to obtain an intermediate 1, 4-diphenyl-2-butene, and performing ozonization and catalytic reduction reaction on the intermediate to obtain phenylacetaldehyde. According to the method, simple raw materials are adopted, through hydrogenation and ozonization conversion, the reaction process is environmentally friendly, the product yield is high, few byproducts are produced, and extremelyhigh atom economy is achieved.
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Paragraph 0055-0064; 0077-0080
(2020/04/17)
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- Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
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The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
- Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
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p. 17305 - 17313
(2019/11/03)
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- Loss and Reformation of Ruthenium Alkylidene: Connecting Olefin Metathesis, Catalyst Deactivation, Regeneration, and Isomerization
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Ruthenium-based olefin metathesis catalysts are used in laboratory-scale organic synthesis across chemistry, largely thanks to their ease of handling and functional group tolerance. In spite of this robustness, these catalysts readily decompose, via little-understood pathways, to species that promote double-bond migration (isomerization) in both the 1-alkene reagents and the internal-alkene products. We have studied, using density functional theory (DFT), the reactivity of the Hoveyda-Grubbs second-generation catalyst 2 with allylbenzene, and discovered a facile new decomposition pathway. In this pathway, the alkylidene ligand is lost, via ring expansion of the metallacyclobutane intermediate, leading to the spin-triplet 12-electron complex (SIMes)RuCl2 (3R21, SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene). DFT calculations predict 3R21 to be a very active alkene isomerization initiator, either operating as a catalyst itself, via a η3-allyl mechanism, or, after spin inversion to give R21 and formation of a cyclometalated Ru-hydride complex, via a hydride mechanism. The calculations also suggest that the alkylidene-free ruthenium complexes may regenerate alkylidene via dinuclear ruthenium activation of alkene. The predicted capacity to initiate isomerization is confirmed in catalytic tests using p-cymene-stabilized R21 (5), which promotes isomerization in particular under conditions favoring dissociation of p-cymene and disfavoring formation of aggregates of 5. The same qualitative trends in the relative metathesis and isomerization selectivities are observed in identical tests of 2, indicating that 5 and 2 share the same catalytic cycles for both metathesis and isomerization, consistent with the calculated reaction network covering metathesis, alkylidene loss, isomerization, and alkylidene regeneration.
- Engel, Julien,Smit, Wietse,Foscato, Marco,Occhipinti, Giovanni,T?rnroos, Karl W.,Jensen, Vidar R.
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supporting information
p. 16609 - 16619
(2017/11/28)
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- Stability and activity of cis-dichloro ruthenium olefin metathesis precatalysts bearing chelating sulfur alkylidenes
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S-Chelated Grubbs type complexes are usually found in their stable cis-dichloro conformation. These precatalysts are usually latent and necessitate external stimuli to promote olefin metathesis reactions. Herein we report the synthesis of new S-chelated ruthenium complexes, by a simple exchange of the benzylidene to an alkylidene chelating ligand. The structure of the complexes was studied by NMR spectroscopy, single crystal X-ray diffraction and DFT calculations. The new complexes were tested in a series of olefin metathesis reactions and were found to be the first cis-dichloro ruthenium precatalysts that are active at room temperature. The observed differences in reactivity and structure between the alkylidene complexes and their benzylidene counterparts highlight the important influence aromaticity may have on the stability and activity of chelated Grubbs type complexes. The findings may also have implications to develop alternative strategies to stabilize, or destabilize, other organometallic complexes bearing relevant chelating ligands.
- Tzur, Eyal,Ivry, Elisa,Diesendruck, Charles E.,Vidavsky, Yuval,Goldberg, Israel,Lemcoff, N. Gabriel
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supporting information
p. 24 - 28
(2014/08/18)
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- Unravelling the olefin cross metathesis on solid support. Factors affecting the reaction outcome
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Olefin cross metathesis on solid support under a variety of conditions is described. A comprehensive analysis considering diverse factors governing the reaction outcome gives a series of patterns for the application of this useful methodology in organic synthesis. If the intrasite reaction is not possible, homodimerization of the soluble olefin is crucial. When the homodimer is less reactive than its monomer, reaction outcome depends on the homodimerization rate, which, in turn, depends on the precatalyst used and the reaction conditions. If the site-site interaction is a feasible process, the cross metathesis product is obtained exclusively when the newly-formed double bond is resilient to further metathetic events. Taking into account these considerations, we have demonstrated that excellent results in terms of cross metathesis coupling can be obtained under the optimized conditions, and that microwave irradiation is also an interesting alternative for the development of a practical and energy-efficient cross metathesis on solid support.
- Poeylaut-Palena, Andres A.,Mata, Ernesto G.
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scheme or table
p. 3947 - 3956
(2010/09/17)
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- Vanadium(I) chloride and lithium vanadium(I) dihydride as selective epimetallating reagents for π- and σ-bonded organic substrates
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Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, whose efficient preparation, structural constitution and mode of reaction toward certain organic substrates have been described in a preceding article, are here evaluated in their reactions toward a wide variety of π- and σ-bonded organic substrates, namely carbonyl, imine, azo, alkene, 1,3-diene, nitrile π-bonds and C-X, C-O, C-N and N-N σ-bonds. Compared with the high reactivity of CrCl and LiCrH2 reagents in attacking both types of bonds, the VCl and LiVH2 reagents were much milder and selective in epimetallating π-bonds, often forming the 1:1 adduct of LiVH2 and π-bonded substrate as the major product. Finally, the vanadium reagents showed little tendency to cleave C-O, C-S and C-N bonds and a smaller scope in cleaving C-X bonds than their chromium counterparts. Because of their selectivity these vanadium reagents offer the following preparative promise: 1) smooth McMurry carbonyl coupling to their reductive dimers; 2) deoxygenation of epoxides; 3) selective aromatic C-X reduction; 4) high yields of epimetallated carbonyls or imines as intermediates to α-hydroxy and α-amino acids; 5) 1,4-reductions of 1,3-alkadienes; 6) reductive dimerization of nitriles to ketones; 7) 1,4 or 1,n-epimetallations leading to acyloins or indoles; and 8) reductive dimerizations of azines to produce unusual imidazole derivatives. In explaining the greater kinetic stability of the 1:1 LiVH2 adduct with carbonyl or imine substrates it is pointed out that such epimetallated adducts from LiVH2 would likely be diamagnetic, whereas such adducts from LiCrH2 have an unpaired electron on the Cr center and hence would rupture, so that the electron would be on the C center. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Eisch, John J.,Fregene, Paul O.
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scheme or table
p. 4482 - 4492
(2009/05/07)
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- Olefin cross-metathesis reactions at room temperature using the nonionic amphiphile "PTS": Just add water
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(Chemical Equation Presented) The first examples of unsymmetrical olefin cross-metathesis reactions in water, involving water-insoluble substrates, at room temperature and using commercially available catalysts are reported. The key to success is to include small percentages of the nonionic, vitamin E-based amphiphile "PTS". The nanometer micelles formed accommodate water-insoluble substrates, along with a readily available Ru-based metathesis catalyst. Reactions proceed at ambient temperatures with high efficiency and very high E-selectivity, and products are easily isolated.
- Lipshutz, Bruce H.,Aguinaldo, Grant T.,Ghorai, Subir,Voigtritter, Karl
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scheme or table
p. 1325 - 1328
(2009/04/10)
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- Salt/ligand-activated low-valent titanium formulations: the 'salt effect' on diastereoselective carbon-carbon bond forming SET reactions
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A comprehensive study on the influence of exogenously added electropositive metal salts as promoters/secondary activators on preformed LVT species has resulted in the construction of highly efficient low-valent titanium (LVT) reagents. These salt-activated LVT reagents while exhibiting enhanced chemoselectivity and diastereoselectivity accelerated the reductive olefination rates of aromatic and aliphatic carbonyls under ambient temperature conditions and in much reduced reaction times. The versatility of the salted reagent was further explored in other single electron transfer reactions, namely, imino-pinacol couplings and one-pot synthesis of phenanthrenes from o-alkoxy aromatic carbonyls. We envisage that, in contrast to multiphase heterogeneous colloidal slurries, salt-activated LVT reagents afforded uniformly viscous homogeneous slurries generating a highly reactive monomeric intermetallic LVT complex. Continued judicious exploration of the emerging paradigms by studying the influence of external ligands/auxiliaries/redox agents on LVT reagents, and organometallics in general, will be critical to widen the scope and utility of the classical McMurry reaction and other SET reactions.
- Rele, Shyam M.,Nayak, Sandip K.,Chattopadhyay, Subrata
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p. 7225 - 7233
(2008/12/20)
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- Regio- and enantiospecific rhodium-catalyzed arylation of unsymmetrical fluorinated acyclic allylic carbonates: Inversion of absolute configuration
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The transition metal-catalyzed allylic substitution with unstabilized carbon nucleophiles represents an important cross-coupling reaction for the construction of ternary carbon stereogenic centers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic alkylation of acyclic unsymmetrical chiral nonracemic allylic alcohol derivatives with aryl zinc bromides. This study demonstrates that the hydrotris(pyrazolyl)borate rhodium catalyst and zinc(II) halide salt are crucial for efficiency, while the addition of lithium bromide to the catalyst is necessary for obtaining optimal regiospecificity. The stereochemical course of this reaction was established through the synthesis of (S)-ibuprofen, which demonstrated that the alkylation proceeds with net inversion of absolute configuration consistent with direct addition of the nucleophile to the metal center followed by reductive elimination. Copyright
- Evans, P. Andrew,Uraguchi, Daisuke
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p. 7158 - 7159
(2007/10/03)
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- Generation of reactive low-valent titanium species using metal-arenes as efficient organic reductants for TiCl3: Applications to organic synthesis
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A comprehensive study on the use of metal-arene systems as organic reductants for TiCl3 has resulted in an efficient method for the generation of highly reactive low-valent titanium (LVT) reagents. The activated titanium species could be prepared by refluxing a mixture of substoichiometric amounts of arenes, TiCl3, and Li/Mg in THF or DME. Among the LVT reagents screened, TiCl3 - Li-naphthalene - THF (reagent I) was the best for coupling of carbonyls to olefins. The reagent could carry out the McMurry olefination of both aromatic and aliphatic substrates at a lower temperature and in a much reduced time as compared to the conventional procedures. Subtle changes in the method of preparation of the LVT reagents influenced the stereoisomeric ratio of the olefins. The reagent was also useful for the synthesis of O- and N- heterocycles and vicinal diamines via intramolecular carbonyl coupling and reductive duplication of imines, respectively.
- Rele,Talukdar,Banerji,Chattopadhyay
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p. 2990 - 2994
(2007/10/03)
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- Activation of Low-Valent Titanium Reagents with Iodine: Facile Low-Temperature McMurry Reaction and N/O-Debenzylation/Deallylation
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A highly reactive, low-valent titanium (LVT) reagent has been prepared by the addition of substoichiometric amounts of iodine to the LVT species generated by Rieke's method (TiCl3-Li-THF). While the conventional McMurry reaction requires high temperatures and prolonged reaction times for the generation of olefins, the present activated LVT reagent is able to effect the reductive coupling of aliphatic as well as aromatic carbonyls to the corresponding olefins at lower temperatures and much reduced reaction times. The protocol is also useful for the intramolecular coupling reactions leading to the one-step synthesis of heterocycles. The temperature-controlled McMurry reaction provides enhanced diastereoselectivity and features an excellent chemoselectivity. In addition to the McMurry reaction, other SET-induced carbon-heteroatom (O, N) bond cleavages can also be carried out with the activated reagent at a fast rate and at a low temperature in high yields.
- Talukdar, Sanjay,Nayak, Sandip K.,Banerji, Asoke
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p. 4925 - 4929
(2007/10/03)
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- Zinc-promoted reactions. 8. The effect of ring strain in the reduction of 1,2-dibenzoylcycloalkanes
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Ring cleavage was the main route in the Zn reduction of 1 in neat AcOH, while selective carbonyl reduction predominated in the presence of LiCl. The less strained 2 underwent only carbonyl reduction with Zn/AcOH. The Clemmensen reduction of both 1 and 2 resulted mainly in acyclic products. The unstrained 3 was fairly resistant towards reduction, and did not undergo ring cleavage.
- Di Vona, Maria Luisa,Luchetti, Luciana,Rosnati, Vittorio
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p. 2949 - 2954
(2007/10/02)
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- Synthesis and LTB4 receptor antagonist activities of the naturally occurring LTB4 receptor antagonist Leucettamine A and related analogues
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The isolation and structure determination of the naturally occurring LTB4 receptor antagonist Leucettamine A (1) was recently reported. Herein we describe the synthesis of this natural product, the preparation of several analogues, and their effectiveness as antagonists of [3H]LTB4 binding to intact human U-937 cells. Total synthesis of Leucettamine A (1) is achieved by a convergent route which takes advantage of the elements of symmetry within the molecule. Syntheses of analogues of 1, which lacked the same degree of symmetry, are achieved by a different approach starting from α- amino acids. The natural product 1 inhibits [3H]LTB4 binding to its receptors on intact human U-937 cells with a K(i) = 3.5 ± 0.8 μM and is devoid of measurable agonist activity at the concentrations tested. 2-Amino imidazole analogues of 1 lacking the dioxolane groups were prepared. Generally these are significantly less potent than 1. However, one (26), designed on the basis of a putative structural overlay with LTB4, demonstrated potency comparable to that of the natural product (K(i) = 2.4 ± 0.2 μM).
- Boehm,Gleason,Pendrak,Sarau,Schmidt,Foley,Kingsbury
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p. 3333 - 3340
(2007/10/02)
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- Secondary Reactions of Sulfenes from Sulfonyl Chlorides and Tertiary Amines. 2. Formation of Episulfones, Sulfonylsulfene - Amine S,N-Adducts and Chlorsulfines from Primary Sulfonyl Chlorides and Tertiary Amines
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The reaction of primary sulfonyl chlorides 1b-m with the tertiary amine bases quinuclidine, DABCO, Me3N, Et3N, Bu3N, EtiPr2N, and 1,2,2,6,6-pentamethylpiperidine is studied in acetonitrile solution between -40 and 80 deg C.The 2,3-dialkylthiirane 1,1-dioxides 4 (trans/cis > 1) and the alkenes 5 1> are obtained in high yields with Et3N at -40 deg C.The stereochemistry is influenced by the amine base B in the ring-closure reaction and partially by epimerization of the episulfones 4.Hindered bases favor the cis, β-branched sulfonyl chlorides the trans isomer.Competing formation of the sulfonylsulfene - amine S,N-adducts 7 is only observed with quinuclidine, DABCO, and Me3N, which are also the most active amines in the epimerization of the cis-2,3-diarylthiirane 1,1-dioxides 4.Methanesulfonyl chloride (1a) yields the mesylsulfene - amine S,N-adducts 7a with Me3N and Et3N in MeCN, but thiirane 1,1-dioxide (4a) with EtiPr2N in MeCN or with Et3N in Et2O.Formation of chlorosulfines 10 is favored by higher temperature (T > 20 deg C), hindered amine bases and β-branched sulfonyl chlorides.Isolation of 10g and 10h in high yields shows that tert-alkylchlorosulfines are rather stable sulfines.
- Opitz, Guenter,Ehlis, Thomas,Rieth, Karlheinz
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p. 1989 - 1998
(2007/10/02)
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- SYMMETRISCHE ALKENE UEBER EPISULFONE AUS PRIMAEREN SULFONYLCHLORIDEN
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Primary sulfonyl chlorides RCH2SO2Cl (R=Alk or Ar) react with triethylamine in acetonitrile solution at -40 degC to give mixtures of cis- and trans-2,3-disubstituted thiirane-1,1-dioxides which can be thermolyzed to the corresponding Z- and E-alkenes.
- Opitz, Guenter,Ehlis, Thomas,Rieth, Karlheinz
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p. 3131 - 3132
(2007/10/02)
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- SELECTIVE REDUCTIONS OF CONJUGATED ACETYLENES WITH MAGNESIUM IN METHANOL AND METHANOL-D
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The combination of magnesium in methanol or methanol-d offers an efficient, convenient and selective method for reduction of acetylenic bonds conjugated to esters (but not acids) or to two phenyl groups to the saturated or tetradeuterated derivatives, respectively.
- Hutchins, Robert O.,Suchismita
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- Electron Transfer and Conformational Interconversions in 1,n-Diphenylpolyenes
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1,4-Diphenylbutadiene (1), 1,6-diphenylhexatriene (2), and 1,8-diphenyloctatetraene (3) are reduced with alkali metals and the resulting paramagnetic monoanions and diamagnetic dianions characterized by ESR and (1H-, 13C-)NMR spectroscopy, respectively.Th
- Schenk, Rainer,Huber, Walter,Schade, Peter,Muellen, Klaus
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p. 2201 - 2208
(2007/10/02)
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- Convenient Redcution of C-C Multiple Bonds Conjugated with Aromatic Rings by PhYbI Complex or Yb Metal
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A variety of C-C multiple bonds conjugated with aromatic rings are smoothly reduced by the PhYbI/MeOH or Yb/MeOH system under very mild conditions to give the corresponding saturated products in excelent yields.This reaction provides a novel convenient method for reduction of multiple bonds conjugated with aromatic rings.
- Hou, Zhaomin,Taniguchi, Hiroshi,Fujiwara, Yuzo
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p. 305 - 308
(2007/10/02)
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- PALLADIUM-CATALYZED REGIO- AND STEREOSELECTIVE DESULFONYLATION OF ALLYLIC SULFONES WITH LiHBEt3. APPLICATION TO THE SYNTHESIS OF SQUALENE
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Allylic p-tolyl sulfones were easily desulfonylated to the corresponding alkenes by LiHBEt3 in the presence of a catalytic amount of under mild conditions with the preservation of the original stereochemistry.This reaction was successfully applied to the synthesis of squalene.
- Mohri, Mitsunobu,Kinoshita, Hideki,Inomata, Katsuhiko,Kotake, Hiroshi
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p. 451 - 454
(2007/10/02)
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- Synthesis of the Aryltetralin Lignan Skeleton via the Prins Reaction
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Reaction of a 1,4-diaryl-1-butene (7) with paraformaldehyde and the appropriate alkylaluminum halide generates the cation 8, via addition of formaldehyde to the double bond, which cyclizes to give the aryltetralin 9.Reaction of 1,4-diphenyl-2-butene (6a) with paraformaldehyde and methylaluminum sesquichloride gives the ene adduct 5a, which reacts further, analogously to 7, to give 4a which possesses the aryltetralin lignan skeleton.
- Snider, Barry B.,Jackson, Andrew C.
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p. 1471 - 1474
(2007/10/02)
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