- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
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The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
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supporting information
p. 6207 - 6227
(2021/05/06)
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- Discovery of TAK-981, a First-in-Class Inhibitor of SUMO-Activating Enzyme for the Treatment of Cancer
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SUMOylation is a reversible post-translational modification that regulates protein function through covalent attachment of small ubiquitin-like modifier (SUMO) proteins. The process of SUMOylating proteins involves an enzymatic cascade, the first step of which entails the activation of a SUMO protein through an ATP-dependent process catalyzed by SUMO-activating enzyme (SAE). Here, we describe the identification of TAK-981, a mechanism-based inhibitor of SAE which forms a SUMO-TAK-981 adduct as the inhibitory species within the enzyme catalytic site. Optimization of selectivity against related enzymes as well as enhancement of mean residence time of the adduct were critical to the identification of compounds with potent cellular pathway inhibition and ultimately a prolonged pharmacodynamic effect and efficacy in preclinical tumor models, culminating in the identification of the clinical molecule TAK-981.
- Langston, Steven P.,Grossman, Stephen,England, Dylan,Afroze, Roushan,Bence, Neil,Bowman, Douglas,Bump, Nancy,Chau, Ryan,Chuang, Bei-Ching,Claiborne, Christopher,Cohen, Larry,Connolly, Kelly,Duffey, Matthew,Durvasula, Nitya,Freeze, Scott,Gallery, Melissa,Galvin, Katherine,Gaulin, Jeffrey,Gershman, Rachel,Greenspan, Paul,Grieves, Jessica,Guo, Jianping,Gulavita, Nanda,Hailu, Shumet,He, Xingyue,Hoar, Kara,Hu, Yongbo,Hu, Zhigen,Ito, Mitsuhiro,Kim, Mi-Sook,Lane, Scott Weston,Lok, David,Lublinsky, Anya,Mallender, William,McIntyre, Charles,Minissale, James,Mizutani, Hirotake,Mizutani, Miho,Molchinova, Nina,Ono, Koji,Patil, Ashok,Qian, Mark,Riceberg, Jessica,Shindi, Vaishali,Sintchak, Michael D.,Song, Keli,Soucy, Teresa,Wang, Yana,Xu, He,Yang, Xiaofeng,Zawadzka, Agatha,Zhang, Ji,Pulukuri, Sai M.
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supporting information
p. 2501 - 2520
(2021/04/02)
-
- Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols
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The treatment of 2-(2-vinylphenyl)acetaldehydes or 3-(2-vinylphenyl)propanals with BF3·Et2O results in an intramolecular Prins reaction affording intermediary benzyl carbenium ions, which are then trapped by a variety of electron-ric
- Meng, Shuyu,Wang, Quanrui,Zheng, Jie
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supporting information
p. 1481 - 1489
(2021/07/02)
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- Enantioselective Construction of Spiro Quaternary Carbon Stereocenters via Pd-Catalyzed Intramolecular α-Arylation
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We herein report the development of a sterically hindered and electron-rich P-chiral monophosphorus biaryl ligand that has enabled a general and efficient enantioselective intramolecular α-arylation, providing access to a wide series of [4.4], [4.5], and [4.6]-spirocycles with chiral benzylic quaternary carbons in high yields with good to excellent enantioselectivities. A pronounced water effect on enantioselectivity is observed.
- Wu, Ting,Kang, Xuehua,Bai, Heng,Xiong, Wenrui,Xu, Guangqing,Tang, Wenjun,Tang, Wenjun
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supporting information
p. 4602 - 4607
(2020/06/29)
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- Substitution-Controlled Selective Formation of Hexahydrobenz[ e]isoindoles and 3-Benzazepines via In(OTf)3-Catalyzed Tandem Annulations
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A dramatic N-substituent controlled tandem annulation of 2-(2-(2-bromoethyl)phenyl)-1-sulfonylaziridines with 1,3-dicarbonyl compounds has been developed. When the N-substituent was a 4-methylbenzenesulfonyl group (Ts), sequential ring opening of aziridin
- Xing, Siyang,Gu, Nan,Wang, Xin,Liu, Jingyi,Xing, Chunyan,Wang, Kui,Zhu, Bolin
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supporting information
p. 5680 - 5683
(2018/09/25)
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- Highly diastereoselective synthesis of tetralin-fused spirooxindoles via lewis acid-catalyzed C(sp3)H bond functionalization
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A highly diastereoselective synthesis of tetralin-fused spirooxindole derivatives was described. Treatment of benzylidene oxindoles with a catalytic amount of Sc(OTf)3 in refluxing hexane afforded the target compounds in good chemical yields with excellent diastereoselectivities (up to >20:1). Detailed investigation of the reaction mechanism revealed that both interconversion of the two diastereomers and their solubility difference in reaction medium were the key to achieving excellent diastereoselectivities.
- Machida, Mizuki,Mori, Keiji
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supporting information
p. 868 - 871
(2018/07/03)
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- Reliably Regioselective Dialkyl Ether Cleavage with Mixed Boron Trihalides
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A protocol for the regioselective cleavage of unsymmetrical alkyl ethers to generate alkyl alcohol and alkyl bromide products is described. A mixture of trihaloboranes triggers this conversion and exhibits improved reactivity profiles (regioselectivity and yield) compared with BBr3 alone. Additionally, this procedure allows the efficient synthesis of (B-Cl) dialkyl boronate esters. There are limited methods to generate acyclic dialkoxyboryl chlorides, and these intermediates constitute important synthons in main-group chemistry.
- Atienza, Bren Jordan P.,Truong, Nam,Williams, Florence J.
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p. 6332 - 6335
(2018/10/09)
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- Antiproliferative activity and SARs of caffeic acid esters with mono-substituted phenylethanols moiety
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A series of CAPE derivatives with mono-substituted phenylethanols moiety were synthesized and evaluated by MTT assay on growth of 4 human cancer cell lines (Hela, DU-145, MCF-7 and ECA-109). The substituent effects on the antiproliferative activity were systematically investigated for the first time. It was found that electron-donating and hydrophobic substituents at 2′-position of phenylethanol moiety could significantly enhance CAPE's antiproliferative activity. 2′-Propoxyl derivative, as a novel caffeic acid ester, exhibited exquisite potency (IC50?=?0.4?±?0.02 & 0.6?±?0.03?μM against Hela and DU-145 respectively).
- Xie, Jin,Yang, Fengzhi,Zhang, Man,Lam, Celine,Qiao, Yixue,Xiao, Jia,Zhang, Dongdong,Ge, Yuxuan,Fu, Lei,Xie, Dongsheng
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p. 131 - 134
(2016/12/27)
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- Triarylphosphine ligands with hemilabile alkoxy groups: Ligands for nickel(II)-catalyzed olefin dimerization reactions. hydrovinylation of vinylarenes, 1,3-dienes, and cycloisomerization of 1,6-dienes
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Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl- and 2-benzyloxymethylphenyldiphenylphosphine (L5 and L6, respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at -55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, affording up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II) complexes of 2- benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl- (L6) and 2-benzyloxyethyldiphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II) complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II) complexes of N-heterocyclic carbene ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions.
- Biswas, Souvagya,Zhang, Aibin,Raya, Balaram,Rajanbabu
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supporting information
p. 2281 - 2292
(2014/07/21)
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- Synthesis of green and blue fluorescent ladder-type conjugated imidazolium compounds
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The synthetic route to ladder-type conjugated imidazolium compounds consisting of Suzuki coupling, chlorination, and intramolecular cyclization reactions was developed. The optical properties of materials and theoretical calculations were investigated to
- Takagi, Koji,Ito, Yohei,Kusafuka, Kazuma,Sakaida, Masanori
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supporting information
p. 2245 - 2248
(2013/04/23)
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- Synthesis of 2,3-dihydro-1-phenylbenzo[b]phosphole (1-phenylphosphindane) and its use as a mechanistic test in the asymmetric appel reaction: Decisive evidence against involvement of pseudorotation in the stereoselecting step
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Racemic 2,3-dihydro-1-phenylbenzo[b]phosphole was obtained by reduction of 1-phenylbenzo[b]phosphole-1-oxide, itself derived by ring-closing metathesis of phenylstyrylvinylphosphine oxide. The title compound was then reoxidized under asymmetric Appel cond
- Carr, Damien J.,Kudavalli, Jaya Satyanarayana,Dunne, Katherine S.,Mueller-Bunz, Helge,Gilheany, Declan G.
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p. 10500 - 10505
(2013/11/06)
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- Facile synthesis of 4,5,6a,7-tetrahydrodibenzo[de,g]chromene heterocycles and their transformation to phenanthrene alkaloids
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Oxa-Pictet-Spengler cyclization and microwave-assisted C-H arylation have been implemented as key steps in the synthesis of new isochroman heterocycles containing a 4,5,6a,7-tetrahydrodibenzo[de,g]chromene motif. These isochromans may be easily transformed to phenanthrene alkaloids via acidic cleavage of the isochroman ring and standard synthetic manipulations thereafter. The route described is attractive in that it provides access to two biologically interesting scaffolds in simple and high yielding synthetic steps.
- Kapadia, Nirav,Harding, Wayne
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p. 8914 - 8920
(2013/09/23)
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- Gold-catalyzed oxidative cyclizations of cis-3-En-1-ynes to form cyclopentenone derivatives
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Golden tendencies: The title reaction for synthesizing cyclopentenone derivatives utilizes a gold complex and 8-methylquinoline oxide as the catalyst system (see scheme; IPr=1,3-bis(diisopropylphenyl)imidazol-2-ylidene). Such products are not attainable using diazocarbonyl reagents, as the gold carbenoids tend to react with C-H bonds. Copyright
- Bhunia, Sabyasachi,Ghorpade, Satish,Huple, Deepak B.,Liu, Rai-Shung
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supporting information; experimental part
p. 2939 - 2942
(2012/05/20)
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- INHIBITORS OF THE RENAL OUTER MEDULLARY POTASSIUM CHANNEL
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This invention relates to compounds having structural Formula I: and pharmaceutically acceptable salts thereof which are inhibitors of the Renal Outer Medullary Potassium (ROMK) channel (Kir1.1). The compounds of Formula I are useful as diuretics and natriuretics and therefore are useful for the therapy and prophylaxis of disorders resulting from excessive salt and water retention, including cardiovascular diseases such as hypertension and chronic and acute heart failure
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Page/Page column 72-73
(2010/11/18)
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- One-pot synthesis of aminoenone via direct reaction of the chloroalkyl enone with NaN3: Rapid access to polycyclic alkaloids
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(Figure presented) A new one-pot procedure for the preparation of aminoenone from chloroalkyl enone and sodium azide was demonstrated. The structure of the presumed triazoline intermediate in this process was confirmed by X-ray analysis for the first time. As the application of this methodology, the synthesis of polycyclic alkaloid hexahydroapoerysopine (1a) was achieved through an efficient synthetic route.
- Zhao, Yu-Ming,Gu, Peiming,Tu, Yong-Qiang,Zhang, Hai-Jun,Zhang, Qing-Wei,Fan, Chun-An
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supporting information; experimental part
p. 5289 - 5295
(2010/10/19)
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- Intramolecular homolytic substitution at the sulfur atom: an alternative way to generate phosphorus- and sulfur-centered radicals
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Two efficient procedures involving tin hydride or thiophenol-mediated intramolecular homolytic substitution at the sulfur atom are reported. They lead to the generation of varied P(V)-centered radicals from the corresponding aryl or alkyne thiophosphorus substrates. The radical formed can be trapped by an olefin via an intermolecular addition, leading to the construction of C-P bonds. Thiophosphination of triple bonds was also achieved using a radical cycloisomerization process. Extension of the methodology to sulfur-containing species was examined.
- Carta, Paola,Puljic, Nicolas,Robert, Carine,Dhimane, Anne-Lise,Ollivier, Cyril,Fensterbank, Louis,Lac?te, Emmanuel,Malacria, Max
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experimental part
p. 11865 - 11875
(2009/04/06)
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- Stereoselective alcohol silylation by dehydrogenative Si-O coupling: Scope, limitations, and mechanism of the Cu-H-catalyzed non-enzymatic kinetic resolution with silicon-stereogenic silanes
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Ligand-stabilized copper(I)hydride catalyzes the dehydrogenative Si-O coupling of alcohols and silanes-a process that was found to proceed without racemization at the silicon atom if asymmetrically substituted. The present investigation starts from this pivotal observation since silicon-stereogenic silanes are thereby suitable for the reagent-controlled kinetic resolution of racemic alcohols, in which asymmetry at the silicon atom enables discrimination of enantiomeric alcohols. In this full account, we summarizeour efforts to systematically examine this unusual strategy of diastereoselective alcohol silylation. Ligand (sufficient reactivity with moderately electron-rich monophosphines), silane (reasonable diastereocontrol with cyclic silanes having a distinct substitution pattern) as well as substrate identification (chelating donor as a requirement) areintroductorily described. With these basic data at hand, the substrate scope was defined employing enantiomerically enriched tert-butyl-substituted 1-silatetraline and highly reactive 1-si-laindane. The synthetic part is complemented by the determination of the stereochemical course at the silicon atom in the Si-O coupling step followed by its quantum-chemical analysis thus providing a solid mechanistic picture of this remarkable transformation.
- Rendler, Sebastian,Plefka, Oliver,Karatas, Betuel,Auer, Gertrud,Froehlich, Roland,Mueck-Lichtenfeld, Christian,Grimme, Stefan,Oestreich, Martin
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supporting information; scheme or table
p. 11512 - 11528
(2009/12/07)
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- Enantio- and diastereotopos differentiation in the palladium(II)-catalyzed hydrosilylation of bicyclo[2.2.1]alkene scaffolds with silicon-stereogenic silanes
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The palladium(II)-catalyzed hydrosilylation of meso-configured bicyclo[2.2.1]alkene scaffolds proved to be an invaluable model reaction for the development of reagent-controlled asymmetric transformations based on silicon-stereogenic silanes as stereoinducers. In the present investigation, the subtle structural requirements of the silane substitution pattern in enantiotopos-differentiating single hydrosilylations of a norbornene-type substrate are disclosed. Extension of this chemistry to a double hydrosilylation of norbornadiene entails a significant increase in stereochemical complexity. Although differentiation of enantiotopic positions by the chiral reagent is demanded in the first hydrosilylation, the same reagent must then differentiate diastereotopic positions in the second. Remarkably high stereocontrol was found in this double hydrosilylation with several silanes first used in the hydrosilylations of the norbornene-type system. Depending on the enantiomeric purity of the silane, C2- and Cs-symmetric adducts, respectively, were obtained. The identity of the key quaternary silanes was revealed by crystallographic analysis. By this method, the relative and absolute configurations were also assigned, which, in turn, imply that all enantiospecific substitutions at silicon proceed with stereoretention. On the basis of these solid-state structures, we also discuss the structural implications of silane substitution for the diastereoselectivity-determining step of this palladium(II)-catalyzed hydrosilylation reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Rendler, Sebastian,Froehlich, Roland,Keller, Manfred,Oestreich, Martin
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supporting information; experimental part
p. 2582 - 2591
(2009/04/05)
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- Effect of chain length on radical to carbanion cyclo-coupling of bromoaryl alkyl-linked oxazolines: 1,3-Areneotropic migration of oxazolines
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(Chemical Equation Presented) 2-Halophenylalkyl-2-oxazolines with alkyl chain spacers of two to six C atoms (n = 0-4) were prepared and their S RN1-type reactions with several base systems examined. The best conditions to promote cyclocoupling to the corresponding benzocycloalkane derivatives involved use of LDA in THF. The precursors with 3-C-atom and 4-C-atom spacers gave good yields of 2-(1′-phenylindan-1′-yl)-2- oxazolines and 2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR spectroscopy showed the intermediates of the LDA-promoted reactions to be radical anions of the product benzocycloalkanes. This supported an SRN1-type chain mechanism involving initial production of aryl radicals connected to azaenolate ions via the spacer groups. Intramolecular radical to carbanion coupling then generated ring-closed benzocycloalkane radical anions that transferred an electron to more precursor. Diastereoselective radical to carbanion cyclo-coupling reactions were carried out with 2-bromophenylpropyl precursors containing chiral 2-oxazolines. The diastereoselectivity achievable was modest, but the product diastereoisomeric Indane derivatives were easily separable by chromatography.
- Marshall, Laura J.,Roydhouse, Mark D.,Slawin, Alexandra M. Z.,Walton, John C.
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p. 898 - 911
(2007/10/03)
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- Indium-catalyzed cycloisomerization of ω-alkynyl-β-ketoesters into six- to fifteen-membered rings
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(Chemical Equation Presented) Many different sizes of rings available: Heating ω-alkynyl-β-ketoesters in the presence of In(NTf 2)3 (Tf=trifluoromethanesulfonyl) produces six- to fifteen-membered ring products in good yields. The reaction features low catalyst loading and moderately dilute conditions, and the formation of medium-sized rings is sometimes faster than that for the corresponding six-membered rings. A synthesis of (±)-muscone is also reported.
- Tsuji, Hayato,Yamagata, Ken-Ichi,Itoh, Yoshimitsu,Endo, Kohei,Nakamura, Masaharu,Nakamura, Eiichi
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p. 8060 - 8062
(2008/09/18)
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- Discovery of a new boron-containing antifungal agent, 5-fluoro-1,3-dihydro- 1-hydroxy-2,1-benzoxaborole (AN2690), for the potential treatment of onychomycosis
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A structure-activity relationship investigation for a more efficacious therapy to treat onychomycosis, a fungal infection of the toe and fingernails, led to the discovery of a boron-containing small molecule, 5-fluoro-1,3-dihydro- 1-hydroxy-2,1-benzoxaborole (AN2690), which is currently in clinical trials for onychomycosis topical treatment.
- Baker, Stephen J.,Zhang, Yong-Kang,Akama, Tsutomu,Lau, Agnes,Zhou, Huchen,Hernandez, Vincent,Mao, Weimin,Alley,Sanders, Virginia,Plattner, Jacob J.
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p. 4447 - 4450
(2007/10/03)
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- Radical-carbanion cyclo-coupling in armed aromatics: Overriding steric hindrance to ring closure
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ω-(2-Halophenyl)alkyl-2-oxazolines were prepared and reacted via base promoted intramolecular coupling of radical with carbanionic centres to yield 1-phenyl-1-oxazolino-indan and -tetralin derivatives containing quaternary C-atoms. The Royal Society of Chemistry 2005.
- Roydhouse, Mark D.,Walton, John C.
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p. 4453 - 4455
(2007/10/03)
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- Esterification of aldehydes and alcohols with pyridinium hydrobromide perbromide in water
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The direct esterification of aldehydes and alcohols was carried out with pyridinium hydrobromide perbromide in water at room temperature. A variety of aldehydes were converted to respective ester derivatives with alcohols such as methanol, 1,2-ethanediol, 1,3-propanediol. Further, a variety of aliphatic alcohols were also converted to the corresponding Tishchenko-like dimeric esters in good yields under the same reaction conditions.
- Sayama, Shinsei,Onami, Tetsuo
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p. 2739 - 2745
(2007/10/03)
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- Synthesis, radiosynthesis and preliminary in vivo evaluation of [ 123I]-(4-fluorophenyl) {1-[2-(2-iodophenyl)ethyl]piperidin-4-yl} methanone, a potential 5-HT2A-antagonist for SPECT brain imaging
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Many people suffer from psychiatric illnesses like depression and anorexia. Relevant to these diseases is amongst others a malfunctioning of brain 5-HT2A-receptors. To allow in vivo quantification of these receptors with Single Photon Emission
- Blanckaert,Vandecapelle,Staelens,Burvenich,Dierckx,Slegers
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p. 591 - 598
(2007/10/03)
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- Amine- and ether-chelated aryllithium reagents - Structure and dynamics
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Chelation and aggregation in phenyllithium reagents with potential 6- and 7-ring chelating amine (2, 3) and 5-, 6-, and 7-ring chelating ether (4, 5, 6) ortho substituents have been examined utilizing variable temperature 6Li and 13C NMR spectroscopy, 6Li and 15N isotope labeling, and the effects of solvent additives. The 5- and 6-ring ether chelates (4, 5) compete well with THF, but the 6-ring amine chelate (2) barely does, and 7-ring amine chelate (3) does not. Compared to model compounds (e.g., 2-ethylphenyllithium 7), which are largely monomeric in THF, the chelated compounds all show enhanced dimerization (as measured by K = [D]/[M]2) by factors ranging from 40 (for 6) to more than 200 000 (for 4 and 5). Chelation isomers are seen for the dimers of 5 and 6, but a chelate structure could be assigned only for 2-(2-dimethylaminoethyl)phenyllithium (2), which has an A-type structure (both amino groups chelated to the same lithium in the dimer) based on NMR coupling in the 15N, 6Li labeled compound. Unlike the dimer, the monomer of 2 is not detectably chelated. With the exception of 2-(methoxymethyl)phenyllithium (4), which forms an open dimer (12) and a pentacoordinate monomer (13), the lithium reagents all form monomeric nonchelated adducts with PMDTA.
- Reich, Hans J.,Goldenberg, Wayne S.,Sanders, Aaron W.,Jantzi, Kevin L.,Tzschucke, C. Christoph
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p. 3509 - 3521
(2007/10/03)
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- Catalyst for aromatic C—O, C—N, and C—C bond formation
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The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.
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- Air stable, sterically hindered ferrocenyl dialkylphosphines for palladium-catalyzed C-C, C-N, and C-O bond-forming cross-couplings
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Pentaphenylferrocenyl di-tert-butylphosphine has been prepared in high yield from a two-step synthetic procedure, and the scope of various cross-coupling processes catalyzed by complexes bearing this ligand has been investigated. This ligand creates a remarkably general palladium catalyst for aryl halide amination and for Suzuki coupling. Turnovers of roughly 1000 were observed for aminations with unactivated aryl bromides or chlorides. In addition, complexes of this ligand catalyzed the formation of selected aryl ethers under mild conditions. The reactions encompassed electron-rich and electron-poor aryl bromides and chlorides. In the presence of catalysts containing this ligand, these aryl halides coupled with acyclic or cyclic secondary alkyl- and arylamines, with primary alkyl- and arylamines, and with aryl- and primary alkylboronic acids. These last couplings provide the first general procedure for reaction of terminal alkylboronic acids with aryl halides without toxic or expensive bases. The ligand not only generates highly active palladium catalysts, but it is air stable in solution and in the solid state. Palladium(0) complexes of this ligand are also air stable as a solid and react only slowly with oxygen in solution.
- Kataoka, Noriyasu,Shelby, Quinetta,Stambuli, James P.,Hartwig, John F.
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p. 5553 - 5566
(2007/10/03)
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- Mapping the melatonin receptor. 6. Melatonin agonists and antagonists derived from 6H-isoindolo[2,1-a]indoles, 5,6-dihydroindolo[2,1- a]isoquinolines, and 6,7-dihydro-5H-benzo[c]azepino[2,1-a]indoles
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6H-Isoindolo[2,1-a]indoles (5, 7, 10, 13), 5,6-dihydroindolo[2,1- a]isoquinolines (20, 21), and 6,7-dihydro-5H-benzo[c]azepino[2,1-a]indoles (23, 25, 27, 30) have been prepared as melatonin analogues to investigate the nature of the binding site of the me
- Faust, Rüdiger,Garratt, Peter J.,Jones, Rob,Yeh, Li-Kuan,Tsotinis, Andrew,Panoussopoulou, Maria,Calogeropoulou, Theodora,Teh, Muy-Teck,Sugden, David
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p. 1050 - 1061
(2007/10/03)
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- Heterocyclic compounds for the treatment of CNS and cardiovascular disorders
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Novel aromatic bicyclic amines of formula (I) STR1 are useful in treating central nervous system disorders and cardiac arrhythmias and cardiac fibrillation.
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- Prostaglandin analogs
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Thromboxane receptor antagonist activity is exhibited by compounds of the formula STR1 wherein: V is --(CH 2) m --, --O--, or STR2 but if V is --O--or STR3 R 3 and R 4 must complete an aromatic ring; W is --(CH 2) 2 --, --CH CH-- or phenylene;X is a single bond, --CH CH--, --(CH 2) n --, or --O--(CH 2) n --; or X is branched alkylene or --O--branched alkylene wherein W is linked to Y through a chain n carbon atoms long;Y is --CO 2 H, --CO 2 alkyl, --CO 2 alkali metal, --CH 2 OH, --CONHSO 2 R 5, --CONHR 6, or --CH 2 -5-tetrazolyl;Z is O or NH;R 3 and R 4 are each independently hydrogen or alkyl or R 3 and R 4 together complete a ring optionally substituted through a ring carbon with a halo, lower alkyl, phenyl, halo (lower alkyl), halophenyl, oxo or hydroxyl group; and the remaining symbols are as defined in the specification.
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- Intramolecular palladium-catalyzed aryl amination and aryl amidation
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Upon treatment with a palladium catalyst and a suitable base, aromatic halides undergo intramolecular substitution to form five, six, and seven-membered rings. In a similar fashion aryl halides with pendant amides or sulfonamides are cyclized to form five and six-membered rings.
- Wolfe, John P.,Rennels, Roger A.,Buchwald, Stephen L.
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p. 7525 - 7546
(2007/10/03)
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- Substrate regulation of product distribution in the reactions of aryl chromium carbene complexes with alkynes
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The reactions of arylcarbene complexes with alkynes were examined for six of the nine possible substitution patterns for mono- and dioxygenated aryl substituents of the carbene carbon. The product distributions were found to be highly dependent on a numbe
- Bos, Mary Ellen,Wulff, William D.,Miller, Ross A.,Chamberlin, Steven,Brandvold, Timothy A.
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p. 9293 - 9319
(2007/10/02)
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- Molecular clefts 2. An analogue of Kagan's ether as a molecular cleft: Synthesis and clathrate formation with ethyl acetate
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A convenient synthesis of 5α,8α, 14α, 17α-5,6,8,9,14,15,17,18 - octahydro-5,17:8,14-diepoxydibenzo[e,e′]benzo[1,2-a:4,5-a′ dicyclooctene (2) is described. This molecular cleft represents the parent of a new class of chiral molecular tweezers. It forms a clathrate with ethyl acetate which is stable even after 12 hours at 0.1 Tort. The structure of 2 was established by spectral and X-ray data. A convenient synthesis of 5a,8a,14a,17a-5,6,8,9,14,15,17,18-octahydro-5,17:8,14-diepoxydibenzo[e, e′]benzo[1,2-a:4,5-a′]icyclooctene (2) is described. It forms a clathrate with ethyl acetate which is stable even after 12 hours at .1 Torr. (Chemical Equation Presented).
- Harmata, Michael,Barnes, Charles L.
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p. 1825 - 1828
(2007/10/02)
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- The Geometry of Displacements at Nonstereogenic Atoms: The Formal Displacement of Alkoxide from Alkoxyamines by Organolithium Reagents
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Amination of organolithium regents can be achieved by reaction with methyllithium-alkoxyamines.Details of the methodology and analysis of the reaction mechanism are presented.Reactions of methyl-, ethyl-, n-butyl-, sec-butyl-, tert-butyl-, phenyl-, and (o-methoxyphenyl)lithium with methyllithium-methoxyamine give the corresponding amines, isolated as the benzamides, in yields of 71-97percent.Lower yields are obtained with o-lithio-N,N-diisopropylbenzamide, 4-lithiodibenzothiophene, n-butylmagnesium bromide, and phenylmagnesium bromide.Reactions of n-butyl, sec-butyl-, tert-butyl-, and phenyllithium with methyllithium-N-methylmethoxyamine provide the corresponding N-methyl-amines, isolated as the benzamides, in yields of 30-70percent.Retention of the N-methyl group in these reactions is considered to rule out a nitrene intermediate.Involvement of a lithium alkoxyamide is suggested by the formation and substitution of that species by two different routes.Dilithiation of N-methoxy-N-amine (17) gives, after an intramolecular reaction and addition of acetyl chloride, N-acetylindoline, in 78percent yield.Dilithiation of N-methyl-N-amine (19) gives N-methyl-N-acetamide (20), after rection with acetyl chloride.The nitrogen transfer in this conversion is shown by a double labeling experiment to be intermolecular.This results is taken to suggest that the bond angles required for displacement cannot be achieved in a six-membered ring, and the mechanism of the reaction involves a complex in which displacement occurs via an SN2-like transition state.The exocyclic-endocyclic intramolecular-intermolecular test is noted to provide a general approach for determination of the geomatry of reactions at nonstereogenic centers.
- Beak, Peter,Basha, Anwer,Kokko, Bruce,Loo, DeKai
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p. 6016 - 6023
(2007/10/02)
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- Synthesis of Biological Markers in Fossil Fuels. 2. Synthesis and 13C NMR Studies of Substituted Indans and Tetralins
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Unambiguous syntheses of all possible methyl, ethyl, n-propyl, and n-butyl derivatives of indan and tetralin were developed using the Kumada coupling procedure involving the reaction of aryl or vinyl halides with Grignard reagents in the presence of nickel(II) chloride.An analysis of the 13C NMR spectra of these compounds was also completed.
- Adamczyk, Maciej,Watt, David S.,Netzel, Daniel A.
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p. 4226 - 4237
(2007/10/02)
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- 1,2-Dihydro-2-imino-1-(bromophenylalkyl)pyrimidines
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Compounds of the formula SPC1 Exhibit central nervous system stimulating properties and act as muscle relaxants.
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