- Highly 3,4-selective living polymerization of 2-phenyl-1,3-butadiene with amidino N-heterocyclic carbene ligated rare-earth metal bis(alkyl) complexes
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A series of amidino N-heterocyclic carbene ligand supported rare-earth metal bis(alkyl) complexes (2,6-R12C6H3NCR2NCH2CH2(NCHCHN(C6H2Me3-2,4,6)C)
- Yao, Changguang,Xie, Hongyan,Cui, Dongmei
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- Effective [3+1+1+1] Cycloaddition to Six-Membered Carbocycle Based on DMSO as Dual Carbon Synthon
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A [3+1+1+1] cycloaddition was developed among 2-arylpropene, ketone and DMSO in the presence of K2S2O8. 2-arylpropene provides three carbons, ketone offers one carbon, and DMSO as dual carbon donor contributes two carbons to the six-membered carbocycle. It gave the cyclohexene motif and spirocyclohexene skeleton. Four C?C bonds formed in this process. Both propylene and ketone could be well tolerated and give the corresponding cyclohexene or spirocyclohexene motif in useful yields. Based on the controlled experiments, a possible mechanism was proposed. (Figure presented.).
- Li, Hui,Su, Miaodong,Nie, Zhiwen,Yang, Tonglin,Luo, Weiping,Liu, Qiang,Guo, Cancheng
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p. 3127 - 3137
(2021/05/17)
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- Efficient Synthesis of 3,6-Dihydro-2H-pyrans via [3+2+1] Annulation Based on the Heteroatom-free Tri-atom Donor
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A new [3+2+1] annulation strategy based on the heteroatom-free tri-atom donor to synthesize 3,6-dihydro-2H-pyrans has been developed. In this method, 2-arylpropylene served as tri-atom donor to contribute three carbon atoms, the heteroatom was provided by aldehyde, and DMSO served as one carbon donor and solvent. This annulation reaction gave 3,6-dihydro-2H-pyrans in moderate to good yields. Based on the control experiments, a possible mechanism was proposed. (Figure presented.).
- Li, Hui,Liu, Haiping,Liu, Yufeng,Cao, Zhongzhong,Su, Miaodong,Fu, Meiqiang,Luo, Weiping,Liu, Qiang,Guo, Cancheng
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p. 5392 - 5399
(2019/11/11)
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- A Cascade Suzuki-Miyaura/Diels-Alder Protocol: Exploring the Bifunctional Utility of Vinyl Bpin
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Cascade reactions are an important strategy in reaction design, allowing streamlining of chemical synthesis. Here we report a cascade Suzuki-Miyaura/Diels-Alder reaction, employing vinyl Bpin as a bifunctional reagent in two distinct roles: as an organoboron nucleo phile for cross-coupling and as a Diels-Alder dienophile. Merging these two reactions enables a rapid and operationally simple synthesis of functionalized carbocycles in good yield. The effect of the organoboron subtype on Diels-Alder regioselectivity was investigated and postsynthetic modifications were carried out on a model substrate. The potential for a complementary Heck/Diels-Alder process was also assessed.
- Cain, David L.,McLaughlin, Calum,Molloy, John J.,Carpenter-Warren, Cameron,Anderson, Niall A.,Watson, Allan J. B.
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p. 787 - 791
(2019/04/25)
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- Regio- and Diastereoselective Iron-Catalyzed [4+4]-Cycloaddition of 1,3-Dienes
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A family of single-component iron precatalysts for the [4+4]-cyclodimerization and intermolecular cross-[4+4]-cycloaddition of monosubstituted 1,3-dienes is described. Cyclooctadiene products were obtained with high regioselectivity, and catalyst-controlled access to either cis- or trans-diastereomers was achieved using 4-substituted diene substrates. Reactions conducted either with single-component precatalysts or with iron dihalide complexes activated in situ proved compatible with common organic functional groups and were applied on multigram scale (up to >100 g). Catalytically relevant, S = 1 iron complexes bearing 2-(imino)pyridine ligands, (RPI)FeL2 (RPI = [2-(2,6-R2-C6H3-Na-CMe)-C5H4N] where R = iPr or Me, L2 = bis-olefin), were characterized by single-crystal X-ray diffraction, M??bauer spectroscopy, magnetic measurements, and DFT calculations. The structural and spectroscopic parameters are consistent with an electronic structure description comprised of a high spin iron(I) center (SFe = 3/2) engaged in antiferromagnetically coupling with a ligand radical anion (SPI = -1/2). Mechanistic studies conducted with these single-component precatalysts, including kinetic analyses, 12C/13C isotope effect measurements, and in situ M??bauer spectroscopy, support a mechanism involving oxidative cyclization of two dienes that determines regio- and diastereoselectivity. Topographic steric maps derived from crystallographic data provided insights into the basis for the catalyst control through stereoselective oxidative cyclization and subsequent, stereospecific allyl-isomerization and C-C bond-forming reductive elimination.
- Kennedy, C. Rose,Zhong, Hongyu,MacAulay, Rachel L.,Chirik, Paul J.
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supporting information
p. 8557 - 8573
(2019/06/04)
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- A General Nickel-Catalyzed Kumada Vinylation for the Preparation of 2-Substituted 1,3-Dienes
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The identification of two nickel(II) precatalysts for the preparation of 2-substituted 1,3-dienes by a Kumada cross-coupling between vinyl magnesium bromide and vinyl phosphates is described. This is noteworthy as engaging only one vinyl derivative in a transition-metal-catalyzed cross-coupling reaction is already reputedly challenging. Salient features of this method are its operational simplicity, the mild reaction conditions, the low catalyst loadings, the short reaction times, its scalability, and the use of stoichiometric quantities of each coupling partner. The tolerance of the two nickel catalysts to an important number of reactive functional groups and their compatibility with structurally complex molecular architectures has been extensively delineated. A Negishi variant of the reaction has been developed for even more sensitive organic functions such as ester or nitrile. Several other conjugated 1,3-dienes with various substitution patterns have been prepared by combining commercial alkenyl Grignard reagents and/or readily available alkenyl enol phosphates. Proper choice of the nickel catalyst and the reaction temperature gave access to a variety of different olefin isomers with high levels of stereocontrol. Overall, this approach affords conjugated dienes that would not be accessible otherwise and therefore provides a valuable complement to existing methods.
- Fiorito, Daniele,Folliet, Sarah,Liu, Yangbin,Mazet, Clément
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p. 1392 - 1398
(2018/02/14)
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- Selective Synthesis of Silacycles by Borane-Catalyzed Domino Hydrosilylation of Proximal Unsaturated Bonds: Tunable Approach to 1,n-Diols
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The tris(pentafluorophenyl)boron-catalyzed domino hydrosilylation of substrates carrying unsaturated functionalities in a proximal arrangement is presented to produce silacycles. Excellent levels of efficiency and selectivity were achieved in the cyclization by the deliberate choice of the hydrosilane reagents. The key to successful cyclic hydrosilylation is the reactivity enhancement of the second intramolecular hydrosilylation by a proximity effect. Not only dienes but also enones, enynes, ynones and enimines readily afford medium-sized silacycles under convenient and mild conditions. The cyclization proceeds with acceptable diastereoselectivity mainly controlled by the conformational bias towards inducing additional stereogenic centers. The silacycles obtained from this reaction were converted to 1,n-diols or 1,n-amino alcohols upon oxidation, thus rendering the present cyclization a powerful tool for accessing synthetically valuable building blocks. (Figure presented.).
- Shin, Kwangmin,Joung, Seewon,Kim, Youyoung,Chang, Sukbok
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supporting information
p. 3428 - 3436
(2017/09/25)
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- Assembly line synthesis of isoprene from formaldehyde and isobutene over SiO2-supported MoP catalysts with active deposited carbon
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Isoprene is a very important monomer for synthetic rubber. Its synthesis in the presence of MoP catalysts via the vapour phase reaction of isobutene with formaldehyde has been studied. The catalysis by various catalysts was characterized by TG analysis, the low-temperature adsorption of nitrogen, XRD, element analysis, TPD, the FT-IR of adsorbed pyridine, XPS and MAS NMR. A chemical process was proposed and confirmed. Isoprene was synthesized in an "assembly line" process through different active sites at the surface of the MoP catalysts, where the active sites were derived from P and Mo species and deposited carbonaceous species. In the induction period, carbon species are preferentially deposited on P species, leading to a decrease in the active Mo and P species (active sites 1), accompanied with a burst in active carbonaceous species (active sites 2). This soundly describes the burst in catalyst capacity in the induction period, which then decreases over time on stream at the expense of the active carbonaceous species. Accordingly, through the prior formulation of sites 1 with sites 2 in a catalyst, the time-consuming induction period can be nearly eliminated. We also observed that a good ratio of these two active sites can efficiently retard the catalyst deactivation. This study clarifies the roles of acid sites and active species in MoP catalysts in the synthesis of isoprene and shows that their optimal ratio can help reduce the length of the induction period and extend the lifetime of the catalysts.
- Qi, Yanlong,Cui, Long,Dai, Quanquan,Li, Yunqi,Bai, Chenxi
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p. 37392 - 37401
(2017/08/09)
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- Exploring Site Selectivity of Iridium Hydride Insertion into Allylic Alcohols: Serendipitous Discovery and Comparative Study of Organic and Organometallic Catalysts for the Vinylogous Peterson Elimination
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The vinylogous Peterson elimination of a broad range of primary, secondary, and tertiary silylated allylic alcohols by two distinct and complementary catalytic systems - a cationic iridium complex and a Br?nsted acid - is reported. These results are unexpected. Nonsilylated substrates are typically isomerized into aldehydes and silylated allylic alcohols into homoallylic alcohols with structurally related iridium complexes. Although several organic acids and bases are known to promote the vinylogous Peterson elimination, the practicality, mildness, functional group tolerance, and generality of both catalysts are simply unprecedented. Highly substituted C=C bonds, stereochemically complex scaffolds, and vicinal tertiary and quaternary (stereo)centers are also compatible with the two methods. Both systems are stereospecific and enantiospecific. After optimization, a vast number of dienes with substitution patterns that would be difficult to generate by established strategies are readily accessible. Importantly, control experiments secured that traces of acid that may be generated upon decomposition of the in situ generated iridium hydride are not responsible for the activity observed with the organometallic species. Upon inspection of the reaction scope and on the basis of preliminary investigations, a mechanism involving iridium-hydride and iridium-allyl intermediates is proposed to account for the elimination reaction. Overall, this study confirms that site selectivity for [Ir-H] insertion across the C=C bond of allylic alcohols is a key parameter for the reaction outcome.
- Li, Houhua,Fiorito, Daniele,Mazet, Clément
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p. 1554 - 1562
(2017/08/15)
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- In Situ Generation of Formaldehyde and Triphenylphosphine from (Hydroxymethyl)triphenylphosphonium and Its Application in Wittig Olefination
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The reaction of (hydroxymethyl)triphenylphosphonium with benzylic or allylic halide under basic conditions at room temperature affords terminal alkenes in 61-89% yields. In this reaction, both formaldehyde and triphenylphosphine are in situ generated from (hydroxymethyl)triphenylphosphonium and further undergo Wittig olefination with benzylic or allylic halide.
- Huang, Wenhua,Xu, Jie
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supporting information
p. 1777 - 1782
(2015/08/06)
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- Soft propargylic deprotonation: Designed ligand enables au-catalyzed isomerization of alkynes to 1,3-Dienes
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By functionalizing the privileged biphenyl-2-ylphosphine with a basic amino group at the rarely explored 3′ position, the derived gold(I) complex possesses orthogonally positioned "push" and "pull" forces, which enable for the first time soft propargylic deprotonation and permit the bridging of a difference of >26 pKa units (in DMSO) between a propargylic hydrogen and a protonated tertiary aniline. The application of this design led to efficient isomerization of alkynes into versatile 1,3-dienes with synthetically useful scope under mild reaction conditions.
- Wang, Zhixun,Wang, Yanzhao,Zhang, Liming
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supporting information
p. 8887 - 8890
(2014/07/08)
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- Ruthenium(II)-catalyzed regioselective reductive coupling of α-imino esters with dienes
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A method for the highly regioselective reductive coupling reaction of N-aryl-α-imino esters with dienes is described. The method utilizes the RuHCl(CO)(PPh3)3/iPrOH catalytic system under an Ar atmosphere and provides α-branched allylic α-amino acid derivatives. Application of this transformation to the concise synthesis of a natural plant growth regulator is demonstrated.
- Zhu, Shujie,Lu, Xiaoxia,Luo, Yueting,Zhang, Wei,Jiang, Huanfeng,Yan, Ming,Zeng, Wei
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supporting information
p. 1440 - 1443
(2013/06/27)
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- 1,7-octadiene-assisted tandem multicomponent cross-enyne metathesis (CEYM)-diels-alder reactions: A useful alternative to Mori's conditions
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The use of 1,7-octadiene as an in situ source of ethylene led us to develop a novel multicomponent tandem cross-enyne metathesis (CEYM)-Diels-Alder reaction. The process can be considered a relay metathesis, in which the ethylene liberated in the ring-closing metathesis (RCM) of 1,7-octadiene initiates the tandem sequence. Aliphatic, aromatic, and fluorinated alkynes and several dienophiles are compatible with the process, which is particularly efficient with aromatic alkynes. This methodology constitutes a useful variant of Mori's conditions in CEYM-related reactions. El empleo de 1,7-octadieno como una fuente in situ de etileno nos ha permitido desarrollar un nuevo proceso tandem multicomponente metatesis cruzada de enino-reaccion de Diels-Alder. El proceso puede considerarse como una metatesis por relevos, donde el etileno liberado en la metatesis con cierre de anillo del 1,7-octadieno inicia la secuencia tandem. Alquinos alifaticos, aromaticos y fluorados y varios dienofilos son compatibles con el proceso, que es particularmente eficiente con alquinos aromaticos. Esta metodologia constituye una variante stil de las condiciones desarrolladas por Mori en reacciones de metatesis cruzada de eninos. Ruthenium catalysis: A new, multicomponent, tandem cross-enyne metathesis (CEYM)-Diels-Alder reaction that is mediated by 1,7-octadiene is described. The ethylene liberated in the ring-closing metathesis of this diene initiates the enyne metathesis and, in the presence of a dienophile, the tandem process takes place in an efficient manner (see scheme). Copyright
- Fustero, Santos,Bello, Paula,Miro, Javier,Simon, Antonio,Del Pozo, Carlos
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experimental part
p. 10991 - 10997
(2012/09/25)
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- Enantioselective construction of all-carbon quaternary centers by branch-selective Pd-catalyzed allyl-allyl cross-coupling
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The Pd-catalyzed cross-coupling of racemic tertiary allylic carbonates and allylboronates is described. This reaction generates all-carbon quaternary centers in a highly regioselective and enantioselective fashion. The outcome of these reactions is consistent with a process that proceeds by way of 3,3′-reductive elimination of bis(η1-allyl)palladium intermediates. Strategies for distinguishing the product alkenes and application to the synthesis of (+)-α-cuparenone are also described.
- Zhang, Ping,Le, Hai,Kyne, Robert E.,Morken, James P.
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p. 9716 - 9719
(2011/08/04)
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- Enantioselective (Formal) Aza-diels-alder reactions with non-danishefsky-type dienes
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Enantioselective (formal) aza-Diels-Alder reactions between acylhydrazones and non-Danishefsky-type dienes have been developed. The reactions are promoted by a simple and economical chiral silicon Lewis acid and are typically conducted at ambient temperature. Both glyoxylate- and aliphatic aldehyde-derived hydrazones may be employed, as may variously substituted dienes, leading to the synthesis of a diverse array of tetrahydropyridines with good to excellent levels of enantioselectivity.
- Tambar, Uttam K.,Lee, Sharon K.,Leighton, James L.
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supporting information; experimental part
p. 10248 - 10250
(2010/09/05)
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- Synthesis of Styrenes by Palladium(II)-Catalyzed Vinylation of Arylboronic Acids and Aryltrifluoroborates by Using Vinyl Acetate
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Reactions of aromatic and heteroaromatic boronic acids or aryltrifluoroborate salts with vinyl acetate in the presence of a palladium(II) catalyst give the corresponding styrenes in good yields. This Heck reaction proceeds with microwave heating in less t
- Lindh, Jonas,Saevmarker, Jonas,Nilsson, Peter,Sjoeberg, Per J. R.,Larhed, Mats
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supporting information; experimental part
p. 4630 - 4636
(2009/12/26)
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- Ruthenium-catalyzed hydroarylations of methylenecyclopropanes: Mild C-H bond functionalizations with conservation of cyclopropane rings
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(Chemical Equation Presented) Ring conservation was observed in the first catalytic intermolecular hydroarylation of methylenecyclopropanes via C-H bond functionalization, a remarkable reactivity mode for a transformation proceeding through (cyclopropylcarbinyl)metal intermediates.
- Kozhushkov, Sergei I.,Yufit, Dmitry S.,Ackermann, Lutz
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supporting information; experimental part
p. 3409 - 3412
(2009/04/21)
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- Pharmaceutical compositions as inhibitors of dipeptidyl peptidase-IV (DPP-IV)
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The present invention relates to compounds, which inhibit dipeptidyl peptidase IV (DPP-IV) and are useful for the prevention or treatment of diabetes, especially type II, as well as hyperglycemia, metabolic syndrome, hyperinsulinemia, obesity, atheroscler
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Page/Page column 25-26
(2010/11/26)
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- The use of a [4 + 2] cycloaddition reaction for the preparation of a series of 'tethered' Ru(ii)-diamine and aminoalcohol complexes
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A series of catalysts have been prepared for use in the asymmetric transfer hydrogenation of ketones. The complexes were prepared using a [4 + 2] cycloaddition reaction at a key step in the reaction sequence. This provides a means for the synthesis of cat
- Cheung, Fung Kei,Hayes, Aidan M.,Morris, David J.,Wills, Martin
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p. 1093 - 1103
(2008/01/01)
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- Homobimetallic ruthenium-N-heterocyclic carbene complexes: Synthesis, characterization, and catalytic applications
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Two new homobimetallic ruthenium-arene complexes [(p-cymene)Ru(μ-Cl) 3RuCl(η2-C2H4)(L)], where L = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (3a) or 1,3-bis(2,4,6- trimethylphenyl)-4,5-dichloroimidazolin-2-ylidene (3b), were isolated in high yields upon heating a toluene solution of [RuCl2 (p-cymene)] 2 with 1 equivalent of carbene ligand under an ethylene atmosphere. They were characterized by NMR and TGA. Their catalytic activity was investigated in the atom transfer radical polymerization of vinyl monomers. In the polymerization of methyl methacrylate, complex 3a displayed faster reaction rates than 3b and the related phosphine-based complex 2a (L = tricyclohexylphosphine), although control was more effective with the latter catalyst. When n-butyl acrylate or styrene served as monomer, a major shift of reactivity was observed between complex 2a that promoted controlled radical polymerization, and complexes 3a or 3b that favored metathetical coupling. Further homocoupling experiments with various styrene derivatives confirmed the outstanding aptitude of complex 3a (and to a lesser extent of 3b) to catalyze olefin metathesis reactions. Contrary to monometallic ruthenium-arene complexes of the [RuCl2(p-cymene)(L)] type, the new homobimetallic species did not require the addition of a diazo compound or visible light illumination to initiate the ring-opening metathesis of norbornene or cyclooctene. When α,ω-dienes were exposed to 3a or 3b, a mixture of cycloisomerization and ring-closing metathesis products was obtained in a non-selective way. Addition of a terminal alkyne co-catalyst enhanced the metathetical activity while completely repressing the cycloisomerization process. Thus, quantitative conversions of diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were achieved within 2 h at room temperature using 2 mol% of catalyst precursor 3 a and 6 mol % of phenylacetylene.
- Sauvage, Xavier,Borguet, Yannick,Noels, Alfred F.,Delaude, Lionel,Demonceau, Albert
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p. 255 - 265
(2008/02/03)
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- Preparation of 2-Trialkylsiloxy-substituted 1,3-dienes and their Diels - Alder/cross-coupling reactions
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2-Triethylsiloxy-substituted 1,3-butadiene has been prepared in gram quantities from chloroprene via a simple synthetic procedure. Silatrane and catechol-substituted analogues of this main group element substituted diene were prepared by ligand exchange a
- Pidaparthi, Ramakrishna R.,Welker, Mark E.,Day, Cynthia S.,Wright, Marcus W.
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p. 1623 - 1626
(2008/02/02)
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- Discovery of ((4R,5S)-5-amino-4-(2,4,5-trifluorophenyl)cyclohex-1-enyl)-3- (trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H-yl)methanone (ABT-341), a highly potent, selective, orally efficacious, and safe dipeptidyl peptidase IV inhibitor
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Dipeptidyl peptidase IV (DPP4) deactivates glucose-regulating hormones such as GLP-1 and GIP, thus, DPP4 inhibition has become a useful therapy for type 2 diabetes. Optimization of the high-throughput screening lead 6 led to the discovery of 25 (ABT-341),
- Pei, Zhonghua,Li, Xiaofeng,Von Geldern, Thomas W.,Madar, David J.,Longenecker, Kenton,Yong, Hong,Lubben, Thomas H.,Stewart, Kent D.,Zinker, Bradley A.,Backes, Bradley J.,Judd, Andrew S.,Mulhern, Mathew,Ballaron, Stephen J.,Stashko, Michael A.,Mika, Amanda K.,Beno, David W. A.,Reinhart, Glenn A.,Fryer, Ryan M.,Preusser, Lee C.,Kempf-Grote, Anita J.,Sham, Hing L.,Trevillyan, James M.
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p. 6439 - 6442
(2008/01/27)
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- Selective C-C bond activation of 2-aryl-1-methylenecyclopropanes promoted by Ir(I) and Rh(I) hydrido complexes. Mechanism of ring-opening isomerization of the strained molecules
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[IrH(CO)(PPh3)3] promotes ring opening of 2-phenyl-1-methylenecyclopropane at room temperature to produce the Ir complex with a chelating 2-phenyl-3-butenyl ligand, [Ir{η2-CH 2CH(Ph)CH=CH2-κC1/s
- Nishihara, Yasushi,Yoda, Chikako,Itazaki, Masumi,Osakada, Kohtaro
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p. 1469 - 1480
(2007/10/03)
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- Tetraorganoindates as Nucleophilic Coupling Partners in Pd-Catalyzed Cross-Coupling Reactions
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(Equation presented) In situ generated ate complex In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1°- and 2°-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency.
- Lee, Phil Ho,Lee, Sung Wook,Seomoon, Dong
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p. 4963 - 4966
(2007/10/03)
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- Preparation, structure, and unique thermal [2 + 2], [4 + 2], and [3 + 2] cycloaddition reactions of 4-vinylideneoxazolidin-2-one
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The terminal allene Cα=Cβ bonds of 4-vinylidene-2-oxazolidinone (2) readily undergo [2 + 2] cycloaddition with a wide variety of terminal alkynes, alkenes, and 1,3-dienes irrespective of their electronic nature under strictly thermal activation conditions (70-100°C) and provide 3-substituted (Z)-methylenecyclobutenes 6, 3-substituted methylenecyclobutanes 7 and 8, and 3-vinylmethylenecyclobutanes 9, respectively, in good to excellent yields. Alkenes react with 2 with complete retention of configuration. The [2 + 2] cycloaddition is concluded to proceed via a concerted [(π2s + π2s)allene + π2s] Hueckel transition state on the basis of experimental evidences and quantum mechanical methods. Some highly polarized enones and nitrile oxide, on the other hand, react with 2 selectively at the internal C4=Cα double bonds and give spiro compounds 10 and 11, respectively. The bent allene bonds (173-176°) and the unique reactivity associated with 2 are attributed to a low-lying LUMO (Cα=Cβ) that is substantiated by a through-space σ*(N-SO2)-π*(Cα= Cβ) orbital interaction.
- Horino, Yoshikazu,Kimura, Masanari,Tanaka, Shuji,Okajima, Toshiya,Tamaru, Yoshinao
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p. 2419 - 2438
(2007/10/03)
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- Decarbopalladation of π-allylpalladium intermediates formed from palladium-catalyzed arylations of 3-allen-1-ols
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eqution presented Unusual palladium-catalyzed arylative fragmentations of acyclic 3-allen-1-ols were observed. Oxidative addition of Pd(0) to aryl halides would form the arylpalladium halides, which added to the central carbon of allenes via carbopalladation to form the π-allylpalladium intermediates. The π-allylpalladium intermediates would be reductively eliminated via carbon-carbon cleavage to give the arylated dienes and the α-hydroxyalkylpalladium intermediates, which were further reductively eliminated to the corresponding aldehydes.
- Oh, Chang Ho,Jung, Seung Hyun,Bang, Su Youn,Park, Dai In
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p. 3325 - 3327
(2007/10/03)
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- IMIDAZOLE DERIVATIVES AND PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME
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The present invention provides a novel imidazole derivative having the chemical formula STR1 These compounds are useful for preventing or treating hypertension or congestive heart failure and have high activity, rapid action upon intravenous injection, go
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- 1,2-Hydrogen migration and alkene formation in the photoexcited states of alkylphenyldiazomethanes
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Laser flash photolysis of alkylphenyldiazomethanes in the presence of pyridine produces easily detected ylides. The data indicate that photolysis of alkylphenyldiazomethanes leads to both carbene formation and direct formation of rearrangement products which do not derive from relaxed carbene intermediates.
- ?elebi, Sol,Leyva, Soccoro,Modarelli, David A.,Platz, Matthew S.
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p. 8613 - 8620
(2007/10/02)
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- New Syntheses of Isomerically Pure Allyl and Propargyl Cyanides by Isocyanide-Cyanide Rearrangement
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A new route for the synthesis of isomerically pure allyl and propargyl cyanides has been developed.Allylic amines are synthesized from the corresponding alcohols by Mitsunobu or by Overman reaction.Formylation with formic acid derivatives provides N-substituted formamides, which are dehydrated to isocyanides. 1,2-Sigmatropic rearrangement by flash pyrolysis provides the isomerically pure allyl and propargyl cyanides. Key Words: Isocyanide-cyanide rearrangment / Cyanides, allyl- and propargyl-
- Wolber, Erwin K. A.,Schmittel, Michael,Ruechardt, Christoph
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p. 525 - 532
(2007/10/02)
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- Silicon-Directed Diene Synthesis
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A synthesis of 2-substituted-1,3-dienes is reported which uses silicon as a control element: eight aldehydes were converted into α-silyl ketones by treatment with trimethylsilylmethylmagnesium chloride and rapid Collins oxidation.Addition of vinylmagnesiu
- Brown, Paul A.,Bonnert, Roger V.,Jenkins, Paul R.,Lawrence, Nicholas J.,Selim, Mohammed R.
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p. 1893 - 1900
(2007/10/02)
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- Novel single step preparation of 2- and 2,3-substituted 1,3-dienes
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An efficient method for preparing 2- and 2,3-substituted 1,3-dienes 2, from ketones 1 by treatment with dimethyloxosulfonium methylide in the presence of sodium methylsulfinylmethide is described.
- Yurchenko,Kyrij,Likhotvorik,Melnik,Zaharzh,Bzhezovski,Kushko
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p. 393 - 394
(2007/10/02)
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- The Direct Formation of Functionalized Alkyl(aryl)zinc Halides by Oxidative Addition of Highly Reactive Zinc with Organic Halides and Their Reactions with Acid Chlorides, α,β-Unsaturated Ketones, and Allylic, Aryl, and Vinyl Halides
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Highly reactive zinc, prepared by the lithium naphthalenide reduction of ZnCl2, readily undergoes oxidative addition to alkyl, aryl, and vinyl halides under mild conditions to generate the corresponding organozinc compounds in excellent yields.Significantly, the reaction will tolerate a spectrum of functional groups on the organic halides.Accordingly, this approach can now be used to prepare a wide variety of highly functionalized organozinc compounds.In the presence of Cu(I) salts, the organozinc compounds cross-couple with acid chlorides, conjugatively add to α,β-unsaturated ketones, and regioselectively undergo SN2' substitution reactions with allylic halides.They also cross-couple with aryl or vinyl halides with Pd(0) catalysts.
- Zhu, Lishan,Wehmeyer, Richard M.,Rieke, Reuben D.
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p. 1445 - 1453
(2007/10/02)
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- A SILICON DIRECTED DIENE SYNTHESIS
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A convenient method for the conversion of a series of aldehydes into substituted dienes is reported which uses silicon as a control element.
- Brown, Paul A.,Bonnert, Roger V.,Jenkins, Paul R.,Selim, Mohammed R.
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p. 693 - 696
(2007/10/02)
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- 4-Bromo-2-sulfolenes. Butadienyl Cation Equivalents
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4-Bromo-2-sulfolene and 4-bromo-3-methyl-2-sulfolene react with alkylcuprates to give direct substitution products, with vinyl- or phenylcuprates or sulfur-containing nucleophiles to give allylic substitution products, and with strongly basic nucleophiles to give elimination products.The allylic substitution products and the isomerized direct substitution products are precursors for substituted 1,3-butadienes.Thus, these 4-bromo-2-sulfolenes serve as butadienyl cation equivalents.
- Chou, Ta-shue,Hung, Su Chun,Tso, Hsi-Hwa
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p. 3394 - 3399
(2007/10/02)
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- Studies on the Autoxidation of 1-Phenylbuta-1,3-diene and 2-Phenylbuta-1,3-diene
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Hydrogenation of the polymeric peroxides formed during the autoxidation of 1-phenylbuta-1,3-diene (1) and 2-phenylbuta-1,3-diene (10) at 50 deg C in an autoclave yielded 1-phenylbutane-3,4-diol (5) and 2-phenylbutane-1,4-diol(12), respectively.The LiAlH4 reduction of 1-phenylbuta-1,3-diene oxidate (50 deg C) yielded cinnamyl alcohols (4) as a major product.The oxygen-containing polymeric products formed along with Diels-Alder dimers during the oxidation of the title substances at 140 deg C showed no degradation after subjecting to hydrogenation and are therefore considered as polyethers.
- Blau, K.,Voerkel,V.,Willecke, L.
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- SYNTHESE STEREOSELECTIVE DE DIENES CONJUGUES A PARTIR D'ALCOOLS α-ALLENIQUES
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The reaction of a Grignard reagent with an α-allenic phosphate leads exclusively in every studied case to 1,3-dienes.A high stereoselectivity is observed for the formation of both double bonds; particularly, the organometallic species attacks preferentially in a trans direction from a group located on the terminal allenic carbon.In the case of the esters of secondary alcohols, it is more difficult to determine the factors which govern the stereochemistry of the other double bond.The Z configuration is then favoured in the reaction phosphate + RMgX but the E configuration is predominant in the reaction acetate + R2CuLi.
- Djahanbini, Dariouche,Cazes, Bernard,Gore, Jacques
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p. 3645 - 3656
(2007/10/02)
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- Chemical process
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Novel 2,4-dihydrocarbylspiro[5.5]undeca-1,4,8-trien-3-one compounds are prepared by reacting an N,N-dihydrocarbyl,2,6-dihydrocarbyl-4-aminomethylphenol with a conjugated diene and an alkyl halide in a liquid solvent medium.
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- Synthesis of Chiral Alk-1-ynes containing an α-Phenylethyl Group
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(R)-4-Phenylpent-1-yne, (R)-(1b), and (S)-5-phenylhex-1-yne, (S)-(1c), have been synthesised from the corresponding chiral alk-1-enes (2) by a stereospecific bromination-dehydrobromination procedure.On the other hand, (R)-3-phenylbut-1-yne, (R)-(1a), has
- Caporusso, Anna Maria,Lardicci, Luciano
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p. 949 - 953
(2007/10/02)
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- SYNTHESIS OF CONJUGATED DIENES BY NICKEL-CATALYZED REACTIONS OF 1,3-ALKADIEN-2-YL PHOSPHATES WITH GRIGNARD REAGENTS
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2-Substitued 1,3-alkadienes were prepared in good yields by reactions of diethyl 1-methyl-2-propenyl phosphate and diethyl 1-methylene-3-phenyl-2-propenyl phosphate with various Grognard reagents in the presence of nickel(II) catalysts.
- Sahlberg, Christer,Quader, Abdul,Claesson, Alf
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p. 5137 - 5138
(2007/10/02)
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- COMPLEXES OF TRANSITION METALS IN THE CHEMISTRY OF CONJUGATED SYSTEMS. III. REACTION OF DIENE HYDROCARBONS WITH ORGANOMAGNESIUM COMPOUNDS IN THE PRESENCE OF SALTS AND COMPLEXES OF TRANSITION METALS
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The effect of the structure of the reagents and the nature of the catalyst on the direction and selectivity in the reaction of 1,3-dienes and their derivatives with aromatic Grignard reagents was investigated.It was shown that in the presence of salts and complexes of iron(III) 1,3-alkadienes R1CH=C(R2)C(R3)=CH2 react with arylmagnesium halides to form trans-(E)-1-aryl-1,3-alkadienes, whereas the sterically hindered (R2, R3=CH3) cyclic 1,3-alkadienes and also 1,2-alkadienes give mainly adducts (1:1).Catalysis by the phosphine complexes of nickel(II) leads to the formation of telomeric (2:1) (E)-1-aryl-2,7- and (E,E)-1-aryl-2,6-alkadienes.The results demonstrate the determining role of the stereochemical conditions for the coordination of the diene in the course of the reaction and also the significant contribution from the processes of one-electron reduction of the catalyst.
- Zubritskii, L. M.,Romashchenkova, N. D.,Petrov, A. A.
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p. 2157 - 2167
(2007/10/02)
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- EVIDENCE FOR THE INTERMEDIACY OF 1,1-DIMETHYL-2-PHENYL-1-SILA-1,3-BUTADIENE IN THE PHOTOCHEMISTRY AND PYROLYSIS OF 1,1-DIMETHYL-2-PHENYL-1-SILA-2-CYCLOBUTENE
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Photolysis of 1,1-dimethyl-2-phenyl-1-sila-2-cyclobutene (I) in methanol and methanol-O-d1 yields dimethylmethoxy(1-phenyl-2-propenyl)silane and dimethylmethoxy(1-d1-1-phenyl-2-propenyl)silane, respectively, as major products.These products may be formed by reaction of methanol or methanol-O-d1 with 1,1-dimethyl-2-phenyl-1-sila-1,3-butadiene.Gas phase pyrolysis of I and acetone or formaldehyde have also been studied.
- Tzeng, Dongjaw,Fong, Raymond H.,Soysa, H. S. Dilanjan,Weber, William P.
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p. 153 - 161
(2007/10/02)
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- Flash Vacuum Pyrolysis of N-Allyl-Substituted 1,3,4-Oxadiazolin-5-ones
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The flash vacuum pyrolysis of several N-allyl-substituted 1,3,4-oxadiazolin-5-ones generates nitrile imines which rearrange to diazoalkenes via a 3,3-sigmatropic shift.
- Padwa, Albert,Caruso, Thomas,Nahm, Steven
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p. 4065 - 4067
(2007/10/02)
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