- Photochemical and chemical electron transfer reactions of bicyclo[2.1.0]pentanes (housanes) in solution and in zeolite cavities
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Photochemical electron transfer (PET) and chemical electron transfer (CET) studies have been conducted in solution and within zeolite cavities for the bicyclo[2.1.0]pentanes (2a-j), prepared by direct photolysis of the corresponding azoalkanes 1. The adva
- Adam, Waldemar,Corma, Avelino,Miranda, Miguel A.,Sabater-Picot, Maria-José,Sahin, Coskun
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- Diastereoselective Diboration of Cyclic Alkenes: Application to the Synthesis of Aristeromycin
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The Pt-catalyzed diboration of cyclic alkenes is extended to unsaturated heterocycles and bicyclic compounds and can be accomplished in a diastereoselective fashion. The optimal procedures, substrate scope, and diastereoselectivity were investigated, and examples employing both homogeneous and heterogeneous catalysis were examined. Lastly, application to the construction of the nucleoside analog (±)-aristeromycin was conducted.
- Vendola, Alex J.,Allais, Christophe,Dechert-Schmitt, Anne-Marie R.,Lee, James T.,Singer, Robert A.,Morken, James P.
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supporting information
p. 2863 - 2867
(2021/05/05)
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- Dinuclear Pathways for the Activation of Strained Three-Membered Rings
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Dinuclear, strain-induced ring-opening reactions of vinylaziridines and vinylcyclopropanes are described. The previously reported [NDI]Ni2(C6H6) complex (NDI = naphthyridine-diimine) reacts with N-tosyl-2-vinylaziridine via C-N oxidative addition to generate a dinickel metallacyclic product. On the basis of this stoichiometric reactivity, the [NDI]Ni2(C6H6) complex is shown to be a highly active catalyst for the rearrangement of vinylcyclopropane to cyclopentene. Notably, 2-phenyl-1-vinylcyclopropane undergoes regioselective activation at the less hindered C-C bond in contrast to the noncatalytic thermal rearrangement. DFT calculations provide insight into the ability of the Ni-Ni bond to stabilize key intermediates and transition states along the catalytic pathway.
- Rounds, Heather R.,Zeller, Matthias,Uyeda, Christopher
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p. 545 - 550
(2018/03/08)
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- Cycloalkyl-based unsymmetrical unsaturated (U2)-NHC ligands: Flexibility and dissymmetry in ruthenium-catalysed olefin metathesis
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Air-stable Ru-indenylidene and Hoveyda-type complexes bearing new unsymmetrical unsaturated N-heterocyclic carbene (U2-NHC) ligands combining a mesityl unit and a flexible cycloalkyl moiety as N-substituents were synthesised. Structural features, chemical stabilities and catalytic profiles in olefin metathesis of this new library of cycloalkyl-based U2-NHC Ru complexes were studied and compared with their unsymmetrical saturated NHC-Ru homologues as well as a set of commercially available Ru-catalysts bearing either symmetrical SIMes or IMes NHC ligands.
- Rouen, Mathieu,Borre, Etienne,Falivene, Laura,Toupet, Loic,Berthod, Mikael,Cavallo, Luigi,Olivier-Bourbigou, Helene,Mauduit, Marc
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supporting information
p. 7044 - 7049
(2014/05/06)
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- Alder-ene reaction of aryne with olefins
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A novel intermolecular Alder-ene reaction based on aryne and olefins was developed. We performed this transformation under mild conditions such as at room temperature, and this reaction displayed high selectivity and good yields only in the presence of CsF. Hence, the intermolecular Alder-ene reaction of aryne with olefins provides an effective route to synthesize derivatives of olefins.
- Chen, Zhao,Liang, Jinhua,Yin, Jun,Yu, Guang-Ao,Liu, Sheng Hua
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supporting information
p. 5785 - 5787
(2013/10/01)
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- Iron-catalyzed allylic arylation of olefins via C(sp3)-H activation under mild conditions
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An aryl Grignard reagent in the presence of mesityl iodide converts an allylic C-H bond of a cycloalkene or an allylbenzene derivative into a C-C bond in the presence of a catalytic amount of Fe(acac)3 and a diphosphine ligand at 0 C. The stereo- and regioselectivity of the reaction, together with deuterium labeling experiments, suggest that C-H bond activation is the slow step in the catalytic cycle preceding the formation of an allyliron intermediate.
- Sekine, Masaki,Ilies, Laurean,Nakamura, Eiichi
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supporting information
p. 714 - 717
(2013/04/10)
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- Enantioselective synthesis of chiral sulfones by ir-catalyzed asymmetric hydrogenation: A facile approach to the preparation of chiral allylic and homoallylic compounds
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A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg-Baecklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).
- Zhou, Taigang,Peters, Byron,Maldonado, Matias F.,Govender, Thavendran,Andersson, Pher G.
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p. 13592 - 13595
(2012/10/08)
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- BINAP versus BINAP(O) in asymmetric intermolecular Mizoroki-Heck reactions: Substantial effects on selectivities
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2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) was employed as chiral ligand in the enantioselective intermolecular Mizoroki-Heck reaction, whereas the use of cognate BINAP(O) (monooxidized BINAP) is unprecedented. The regio- and enantioselectivity of the arylation of representative cyclic alkenes changes dramatically in the presence of hemilabile BINAP(O) instead of BINAP. The arylation of 2,3-dihydrofuran is perfectly regiodivergent (98:2 versus 0:100) and the arylation of cyclopentene is only enantioselective with BINAP(O) [60 versus 10% enantiomeric excess (ee)]. Use of [Pd2(dba)3]·dba (dba=dibenzylideneacetone) instead of Pd(OAc)2 produces as high as 86% ee in the arylation of cyclopentene.
- Woeste, Thorsten H.,Oestreich, Martin
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experimental part
p. 11914 - 11918
(2011/11/29)
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- Mild two-step process for the transition-metal-free synthesis of carbon-carbon bonds from allylic alcohols/ethers and grignard reagents
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Chemical Equation Represented A mild two-step process for the regioselective, transition-metal-free preparation of carbon-carbon bonds from allylic alcohols/ethers and Grignard reagents is described. This process obviates the need for the harsh deprotecti
- Han, Xinping,Zhang, Yanhua,Wu, Jimmy
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supporting information; experimental part
p. 4104 - 4106
(2010/05/15)
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- Mechanism of the Ni(0)-catalyzed vinylcyclopropane-cyclopentene rearrangement
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(Chemical Equation Presented) A combination of physical organic experiments and quantum chemical calculations were used to construct a detailed mechanistic model for the Ni(0)-N-heterocyclic carbene-catalyzed vinylcyclopropane- cyclopentene rearrangement
- Wang, Selina C.,Troast, Dawn M.,Conda-Sheridan, Martin,Zuo, Gang,LaGarde, Donna,Louie, Janis,Tantillo, Dean J.
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supporting information; experimental part
p. 7822 - 7833
(2010/01/16)
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- Direct coupling of alcohols with alkenylsilanes catalyzed by indium trichloride or bismuth tribromide
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Indium halides or bismuth halides catalyzed the coupling of various alcohols with alkenylsilanes to give the corresponding alkenes stereospecifically without any other activators. The Royal Society of Chemistry 2008.
- Nishimoto, Yoshihiro,Kajioka, Masayuki,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
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supporting information; body text
p. 6396 - 6398
(2009/04/13)
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- Highly active nickel, catalysts for the isomerization of unactivated vinyl cyclopropanes to cyclopentenes
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Inflatable rings: Low-valent Ni0-nitrogen-heterocyclic carbene catalysts were found to isomerize activated and unactivated vinyl cyclopropanes to their respective substituted cyclopentenes under mild conditions and in high yields (see scheme, cod = cycloocta-1,5-diene).
- Zuo, Gang,Louie, Janis
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p. 2277 - 2279
(2007/10/03)
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- Heck reaction in water with amphiphilic resin-supported palladium-phosphine complexes
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The Heck reaction of various aryl halides and alkenes took place in water in the presence of an amphiphilic polystyrene-poly(ethylene glycol) resin-supported palladium-phosphine complex to give the corresponding styrene derivatives in quantitative yields.
- Uozumi, Yasuhiro,Kimura, Tsutomu
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p. 2045 - 2048
(2007/10/03)
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- A rapid and general access to 3-arylpiperidines
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A short and efficient synthetic sequence to produce a wide variety of 3-arylpiperidines from three simple building blocks is described. The key step is a palladium-catalyzed arylation of cyclopentene.
- Büchner, Isabel K.,Metz, Peter
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p. 5381 - 5383
(2007/10/03)
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- Highly selective palladium-catalyzed Heck reactions of aryl bromides with cycloalkenes
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Formula presented The influence of palladium catalysts and reaction conditions on the selectivity of Heck reactions of aryl bromides with cyclohexene and cyclopentene has been investigated. It is shown that the addition of DMSO as a cosolvent leads to improved selectivities of nonconjugated aryl olefins. On the other hand, high selectivities for conjugated arylcyclopentenes have been obtained with the catalytic system DMA/Na2-CO3/Pd2(dba) 3·dba/PCy3.
- Hartung, Christian G.,Koehler, Klaus,Beller, Matthias
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p. 709 - 711
(2008/02/11)
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- Tailoring aqueous solvents for organic reactions: Heck coupling reactions in high temperature water
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High temperature water is demonstrated to be an effective solvent for Heck coupling reactions of aromatic halides with cyclic alkenes without the addition of co-solvents or specialized ligands. Reactions in the presence of LiCl and quaternary ammonium salts indicate that the reaction takes place in the aqueous phase.
- Gron,Tinsley
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p. 227 - 230
(2007/10/03)
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- 4-arylcyclopenta[c]pyrrole analgesics
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The 4-arylcyclopenta[c]pyrroles of the following formula are effective analgesics: STR1 including stereoisomers and pharmaceutically acceptable salts thereof, wherein STR2 with the proviso that the 3a and 6a hydrogens are cis and where there is a 4-position hydroxy then such is trans to the 3a and 6a hydrogens, and with the proviso that Rb is not hydrogen when the 4-position aryl is cis to the 3a and 6a hydrogens and there is no hydroxy at the 4-position.
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- Tris(aryl)aminium hexachloroantimonates: Convenient one-electron oxidants for chemical electron transfer with bicyclic azoalkanes and bicyclo[2.1.0]pentanes
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Treatment of the parent and bridgehead-substituted 2,3-diazabicyclo[2.2.1]hept-2-enes (1a-d) and their bicyclo[2.1.0]pentanes (2a-d) with catalytic amounts (2-10 mol%) of tris(aryl)aminium hexachloroantimonates afforded the corresponding cyclopentenes (3a-d). A reversal in the regioselectivity of the 1,2 migration was observed for the unsymmetrical derivatives of bicyclo[2.1.0]pentane, namely 2b (methyl substitution) versus 2c (phenyl substitution). This surprising fact is rationalized in terms of delocalization of the positive charge into the aromatic ring for the 1,3-diyl radical cation, as corroborated by AM1 calculations.
- Adam, Waldemar,Sahin, Coskun
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p. 9027 - 9030
(2007/10/02)
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- Are perpendicular alkene triplets just 1,2-biradicals? Studies with the cyclopropylcarbinyl clock
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Thermochemical studies of perpendicular alkene triplets demonstrate that their energies are almost exactly those expected from Benson estimations using group equivalents for appropriate free radicals as models for the termini (the two essential carbons of the alkene triplet). If these species are to be described as 1,2-biradicals, their reactivities in reactions for which the termini act independently should be similar to corresponding reactivities for appropriate free-radical models. We have used the "cyclopropylcarbinyl clock", the rearrangement of a cyclopropylcarbinyl radical to the corresponding homoallyl radical, to test such a model. We have synthesized cis- and trans-β-cyclopropylstyrene (cis-1 and trans-1), α-cyclopropylstyrene (2), α-cyclopropylindene (3), and β-cyclopropylindene (4). We have studied their triplet chemistry and have examined the transients produced upon triplet sensitization by nanosecond laser flash photolysis. The results are consistent with two basic hypotheses: (1) that, when able to access the perpendicular configuration, cyclopropylcarbinyl ring opening occurs at the rate expected from an appropriate monoradical model and (2) that, when constrained in a higher energy (near-planar) geometry, the rate of ring opening is accelerated.
- Caldwell, Richard A.,Zhou, Lingwen
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p. 2271 - 2275
(2007/10/02)
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- Reactions of Azo and Azoxy Sulphones with Transition Metal Complexes. Part 7. Arylation of Olefins with Arylazoxy Aryl Sulphones Catalysed by a Palladium(0) Phosphine Complex
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The arylation of acyclic and cyclic olefins by arylazoxy aryl sulphones has been investigated in the presence of a palladium(0) catalyst in benzene.Both of the aryl groups of the arylazoxy aryl sulphones are found to participate in the arylation.Two equivalents of aryl-substituted olefins were obtained when the reactions were carried out at 80 deg C, whereas one equivalent of olefin was arylated at 120 deg C.A plausible catalytic cycle involving a diarylpalladium(II) species is proposed.
- Kamigata, Nobumasa,Fukushima, Takamasa,Satoh, Akira,Kameyama, Masayuki
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p. 549 - 553
(2007/10/02)
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- Arylation of Olefins by Arylazo Aryl Sulfones under Palladium(0) Catalysis
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Palladium(0)-catalyzed reaction of arylazo aryl sulfones with olefins in benzene at 80 deg C gave aryl-substituted olefins in good yield.Diarylpalladium(II) species was proposed as an intermediate in this reaction.
- Kamigata, Nobumasa,Satoh, Akira,Kondoh, Tetsuya,Kameyama, Masayuki
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p. 3575 - 3580
(2007/10/02)
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- PALLADIUM-CATALYZED INTERMOLECULAR ALLYLIC ARYLATION OF CYCLOALKENES
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Aryl halides and cycloalkenes undergo palladium-catalyzed, intermolecular, allylic cross-coupling in excellent yields under exceptionally mild reaction conditions.
- Larock, Richard C.,Baker, Bruce E.
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p. 905 - 908
(2007/10/02)
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- 76. Solvolysis Mechanism of cis- and trans-2-Arylcyclopentyl p-Toluenesulfonates. Subsequent Step in trans-2-Phenylclopentyl p-Toluenesulfonate Solvolysis
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The solvolysis of the 1-deuteriated, 2-deuteriated, and undeuteriated trans-2-phenylcyclopentyl p-toluenesulfonate in HCOOH, AcOOH, and EtOH has been studied.We have shown that the classical secondary carbocation arising from substrate ionisation undergoes three concurrent processes, namely kc (direct product formation), kip (hydrogenium bridged ion formation as tertiary carbocation or products precursor) and kΔph (phenonium-ion formation as retained product precursor).The kΔpd process contribution increases with solvent ionising power.The kinetic isotope effect of D-C(1) shows, that the steps following ionisation have a preponderant effect on the total solvolysis rate.
- Ronco, G.,Guyon, R.,Villa, P.
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p. 674 - 684
(2007/10/02)
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- 74. Solvolysis Mechanism of cis- and trans-2-Arylcyclopentyl p-Toluenesulfonates. Subsequent Step in cis-2-Arylcyclopentyl p-Toluenesulfonate Solvolysis
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The solvolysis of a series of 1-deuteriated, 2-deuteriated, and undeuteriated cis-2-arylcyclopentyl p-toluenesulfonates in HCOOH, AcOH, and EtOH has been studied.We have shown that the classical secondary carbocation arising from substrate ionisation undergoes two concurrent processes, namely kc (direct products formation) and kip (hydrogenium bridged ion formation as tertiary carbocation or products precursor).The intrinsic properties of solvent and the aryl substituent electronic effects only affect the total solvolysis rate and the respective contributions of kc and kip processes.Comparing the observed and calculated kinetic isotope effects of D-C(2) allows one to conclude that no step can be called 'rate-determining step' but that the steps following ionisation have a preponderent effect on the total solvolysis rate.
- Ronco, G.,Guyon, R.,Villa, P.
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p. 658 - 673
(2007/10/02)
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- New Method for the Classification of Nucleophiles in the Palladium-Catalyzed Substitution of Allylic Acetates
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Palladium-catalyzed reactions of nucleophiles were carried out on cyclopent-2-enyl acetate (1), 3a,4,5,6,7,7a-hexahydro-(1α,3aα,4α,7α,7aα)-4,7-methano-1H-inden-1-yl acetate (3b), and 3a,4,5,6,7,7a-hexahydro-(1β,3aα,4α,7α,7aα)-4,7-methano-1H-inden-1-yl acetate (5b) to give indications on the mechanism of the reaction and the mode of attack of the nucleophiles.The lack of reactivity of 3b confirmed that a trans relationship between the approaching Pd(O) complex and the departing acetate is required in the η3-allyl-forming step.Examination of the reactivity of the nucleophiles with 5b compared to 1 allowed a decision as to whether the primary attack of the intermediate (η3-allyl)palladium complex by the nucleophile is directed to η3-allylic ligand (Nu1 nucleophiles: sodium dimethyl malonate, sodium cyclopentadienide, lithium thioxodiphenylphosphide, morpholide) or to the metal (Nu2 nucleophiles: phenylzinc chloride, sodium indenide, ammonium formate).
- Fiaud, Jean-Claude,Legros, Jean-Yves
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p. 1907 - 1911
(2007/10/02)
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- Elimination Promoted by Weak Bases. IX. Stereochemistry of Olefin Formation from trans-2-Phenylcyclopentyl p-Bromobenzenesulfonate Promoted by Lithium Chloride in Acetone
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Parker, Winstein, and their coworkers have previously established that in the E2C elimination of trans-2-phenylcyclopentyl p-bromobenzenesulfonate induced by Bu4NCl in acetone some 9percent of the olefinic product is produced by a syn-elimination.In view of the current idea that syn-eliminations in solution are assisted by association of the base with its counterion, the stereochemistry of the reaction induced by lithium chloride in acetone has been studied.There is no increase in the amount of syn-elimination, and kinetic analysis reveals that lithium chloride ion pairs are completely unreactive. 1-Phenylcyclopentene is not produced by rate-limiting attack of chloride on a preformed symmetrical phenonium ion pair.These results do not serve to distinguish between two alternative models of the E2C transition state.
- McLennan, Duncan J.,Lim, Gaik-Choo
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p. 1821 - 1830
(2007/10/02)
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- Palladium(0)-Catalyzed Arylation of Olefins by Arylamines and an Alkyl Nitrite
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Various olefins were arylated by the combination of arylamines and tert-butyl nitrite under palladium catalysis in the presence of acid such as monochloroacetic or acetic.The reaction proceeded in good yields without serious effects from substituents on either the olefinic substrates or the arylamines, including 3-aminopyridine.
- Kikukawa, Kiyoshi,Maemura, Koji,Kiseki, Yasuyuki,Wada, Fumio,Matsuda, Tsutomu,Giam, Choo S.
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p. 4885 - 4888
(2007/10/02)
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- REACTION OF DIAZONIUM SALTS WITH TRANSITION METALS-III. PALLADIUM(0)-CATALYZED ARYLATION OF UNSATURATED COMPOUNDS WITH ARENEDIAZONIUM SALTS
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Palladium (0) catalyzed reactions of arenediazonium salts for arylation of aliphatic and cyclic olefins and allylic alcohols, styrene and ethyl acrylate were studied.Effect of the olefinic compounds and other reaction variables on the arylation were presented.Arylpalladium species was proposed as the most plausible intermediated in this reaction.
- Kikukawa, K.,Nagira, K.,Wada, F.,Matsuda, T.
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- DIRECT TRANSFORMATION OF ARYLAMINES TO ALKENYLARENES UNDER PALLADIUM(0) CATALYSIS
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Olefins could be arylated in good yields by the combination of arylamines (substituted anilines: 4-Me, 4-Cl, 4-Br, 2-NO2, 4-NO2, and 3-aminopyridine) and t-butyl nitrite under palladium(0) catalysis.
- Kikukawa, Kiyoshi,Maemura, Koji,Nagira, Kazuhiko,Wada, Fumio,Matsuda, Tsutomu
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p. 551 - 552
(2007/10/02)
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