- Diastereoselective Synthesis of the ABCD Ring System of Rubriflordilactone B
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A novel nine-step diastereoselective route to the ABCD ring system of the natural product rubriflordilactone B is reported. Use of an α-substituted butenolide derived from maleic anhydride facilitated a 1,4-conjugate addition to provide a diene. The order in which a ringclosing metathesis and enolate oxidation were performed on this compound dictated the relative stereochemistry of the target. The final product exhibited anisotropic effects during roomerature NMR studies, requiring elevatederature experiments to confirm its identity.
- Roth, Hudson G.,Nicewicz, David A.
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- Copper-Catalyzed Modular Amino Oxygenation of Alkenes: Access to Diverse 1,2-Amino Oxygen-Containing Skeletons
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Copper-catalyzed alkene amino oxygenation reactions using O-acylhydroxylamines have been achieved for a rapid and modular access to diverse 1,2-amino oxygen-containing molecules. This transformation is applicable to the use of alcohols, carbonyls, oximes, and thio-carboxylic acids as nucleophiles on both terminal and internal alkenes. Mild reaction conditions tolerate a wide range of functional groups, including ether, ester, amide, carbamate, and halide. The reaction protocol allows for starting with free amines as the precursor of O-benzoylhydroxylamines to eliminate their isolation and purification, contributing to broader synthetic utilities. Mechanistic investigations reveal the amino oxygenation reactions may involve distinct pathways, depending on different oxygen nucleophiles.
- Hemric, Brett N.,Chen, Andy W.,Wang, Qiu
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supporting information
p. 1468 - 1488
(2019/01/25)
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- Enantioselective Copper-Catalyzed Desymmetrization of 1,3-Diketones Involving Borylation of Styrenes
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A copper-catalyzed intramolecular enantioselective and diastereoselective borylative coupling of styrenes and ketones was achieved by merging desymmetrization strategy and olefin difunctionalization. The reaction proceeds through an initial enantioselective borylcupration of styrenes, followed by a highly selective direct addition to 1,3-diketones. The bicyclic scaffolds with three chiral carbon centers, including two tetrasubstituted carbons, were generated in excellent yields, diastereoselectivities, and enantioselectivities. This catalytic tandem reaction has great potential for further synthetic application of the chiral polycyclic compounds, because of the versatility of the functional groups in the products.
- Zheng, Purui,Han, Xiaoyu,Hu, Jiao,Zhao, Xiaoming,Xu, Tao
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p. 6040 - 6044
(2019/08/27)
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- Direct Wittig Olefination of Alcohols
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A base-promoted transition metal-free approach to substituted alkenes using alcohols under aerobic conditions using air as the inexpensive and clean oxidant is described. Aldehydes are relatively difficult to handle compared to corresponding alcohols due to their volatility and penchant to polymerize and autoxidize. Wittig ylides are easily oxidized to aldehydes and consequently form homo-olefination products. By the strategy of simultaneously in situ generation of ylides and aldehydes, for the first time, alcohols are directly transferred to olefins with no need of prepreparation of either aldehydes or ylides. Thus, the di/monocontrollable olefination of diols is accomplished. This synthetically practical method has been applied in the gram-scale synthesis of pharmaceuticals, such as DMU-212 and resveratrol from alcohols.
- Li, Qiang-Qiang,Shah, Zaher,Qu, Jian-Ping,Kang, Yan-Biao
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p. 296 - 302
(2018/02/19)
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- Stable Zero-Valent Nickel Nanoparticles in Glycerol: Synthesis and Applications in Selective Hydrogenations
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Small (mean diameter, ca. 1.2 nm) and well-dispersed zero-valent nickel nanoparticles (NiNPs) stabilized by cinchona-based alkaloids and TPPTS (tris(3-sulfophenyl)phosphine trisodium salt), were synthesized from the organometallic precursor [Ni(cod)2] in neat glycerol under hydrogen pressure. NiNPs were fully characterized ((HR)-TEM, EDX, XPS, XRD, IR, magnetization), both at solid state and directly from the corresponding colloidal solutions in glycerol due to its negligible vapour pressure. NiNPs dispersed in glycerol were applied in hydrogenation reactions, in particular in semihydrogenation of alkynes to give (Z)-alkenes under satisfactory conditions (3 bar H2, 1 mol% Ni, 100 °C), showing remarkable activity and selectivity. The catalytic phase was recycled at least ten times without loss of activity, affording in each case metal-free organic products. Other functional groups such as nitro, nitrile and formyl groups were efficiently hydrogenated to the corresponding anilines, benzylamines and benzylalcohols respectively (77–95% yields). (Figure presented.).
- Reina, Antonio,Favier, Isabelle,Pradel, Christian,Gómez, Montserrat
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supporting information
p. 3544 - 3552
(2018/08/01)
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- Synthesis of Phthalans Via Copper-Catalyzed Enantioselective Cyclization/Carboetherification of 2-Vinylbenzyl Alcohols
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Enantiomerically enriched phthalans were synthesized efficiently via an enantioselective copper-catalyzed alkene carboetherification reaction. In this reaction, 2-vinylbenzyl alcohols enantioselectively cyclize then couple with vinylarenes. The utility of the method was demonstrated by the enantioselective synthesis of (R)-fluspidine, a σ1 receptor ligand.
- Chen, Dake,Chemler, Sherry R.
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supporting information
p. 6453 - 6456
(2018/10/24)
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- C- ARYL GLYCOSID DERIVATIVES, PHARMACEUTICAL COMPOSITION, PREPARATION PROCESS AND USES THEREOF
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This invention relates to a kind of C-aryl glycoside derivatives, its pharmaceutical compositions, preparation methods, and uses thereof. The preparation method comprises: method 1: in a solvent, deprotecting the acetyl protecting groups of compound 1-f in the presence of a base; method 2: 1) compound 2-g reacts with via Mitsunobu reaction; 2) deprotecting the acetyl protecting groups of compound 2-f obtained from step 1; method 3: 1) compound 2-g reacts with via nucleophilic substitution reaction; 2) deprotecting the acetyl protecting groups of compound 3-f obtained from step 1. The pharmaceutical composition comprises a kind of C-aryl glycoside derivatives; it's pharmaceutically acceptable salts and/or prodrugs thereof and excipient thereof. This invention further relates to a kind of C-aryl glycoside derivatives, it's pharmaceutically acceptable salts or pharmaceutical compositions thereof for the use in preparation of a SGLT inhibitor. The C-aryl glycoside derivatives of this invention provides a new direction for the study of SGLT inhibitors.
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- Enantioselective allylation of selected ortho-substituted benzaldehydes: A comparative study
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We report a systematic study of the allylation of ortho-substituted benzaldehydes under catalysis of a Lewis base (N, Ndioxide), a Lewis acid (Keck allylation), and a Bronsted acid. ortho-Halobenzaldehydes were used as the aldehydic substrates, and specia
- Hessler, Filip,Betk, Robert,Kadlkov, Aneta,Belle, Roman,Kotora, Martin
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supporting information
p. 7245 - 7252
(2015/01/09)
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- Endo-selective pd-catalyzed silyl methyl heck reaction
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A palladium (Pd)-catalyzed endo-selective Heck reaction of iodomethylsilyl ethers of phenols and aliphatic alkenols has been developed. Mechanistic studies reveal that this silyl methyl Heck reaction operates via a hybrid Pd-radical process and that the silicon atom is crucial for the observed endo selectivity. The obtained allylic silyloxycycles were further oxidized into (Z)-alkenyldiols.
- Parasram, Marvin,Iaroshenko, Viktor O.,Gevorgyan, Vladimir
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supporting information
p. 17926 - 17929
(2015/03/04)
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- Flow Chemistry Syntheses of Styrenes, Unsymmetrical Stilbenes and Branched Aldehydes
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Two tandem flow chemistry processes have been developed. A single palladium-catalysed Heck reaction with ethylene gas provides an efficient synthesis for functionalised styrenes. Through further elaboration the catalyst becomes multi-functional and performs a second Heck reaction providing a single continuous process for the synthesis of unsymmetrical stilbenes. In addition, the continuous, rhodium-catalysed, hydroformylation of styrene derivatives with syngas affords branched aldehydes with good selectivity. Incorporation of an in-line aqueous wash and liquid-liquid separation allowed for the ethylene Heck reaction to be telescoped into the hydroformylation step such that a single flow synthesis of branched aldehydes directly from aryl iodides was achieved. The tube-in-tube semi-permeable membrane-based gas reactor and liquid-liquid separator both play an essential role in enabling these telescoped flow processes.
- Bourne, Samuel L.,O'Brien, Matthew,Kasinathan, Sivarajan,Koos, Peter,Tolstoy, Paeivi,Hu, Dennis X.,Bates, Roderick W.,Martin, Benjamin,Schenkel, Berthold,Ley, Steven V.
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p. 159 - 172
(2013/03/13)
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- Remarkable improvement achieved by imidazole derivatives in ruthenium-catalyzed hydroesterification of alkenes using formates
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Imidazole derivatives are revealed to be effective ligands in the Ru-catalyzed hydroesterification of alkenes using formates, affording one-carbonelongated esters in high yields. Further, intramolecular hydroesterification was successfully performed to give lactones for the first time. Imidazole derivatives can contribute to promote the reaction as well as to suppress the undesired decarbonylation of formate. Toxic CO gas, a directing group, and large excess alkenes are not required.
- Konishi, Hideyuki,Muto, Takashi,Manabe, Kei,Ueda, Tsuyoshi
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supporting information
p. 4722 - 4725,4
(2012/12/12)
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- Selective iron-catalyzed transfer hydrogenation of terminal alkynes
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A novel iron-catalyzed transfer hydrogenation of alkynes to the corresponding alkenes applying formic acid as a hydrogen donor is reported. An in situ combination of Fe(BF4)2·6H2O and tetraphos allows for highly selective hydrogenation of a broad range of aromatic and aliphatic alkynes tolerating different functional groups.
- Wienhoefer, Gerrit,Westerhaus, Felix A.,Jagadeesh, Rajenahally V.,Junge, Kathrin,Junge, Henrik,Beller, Matthias
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supporting information; experimental part
p. 4827 - 4829
(2012/06/04)
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- The continuous-flow synthesis of styrenes using ethylene in a palladium-catalysed heck cross-coupling reaction
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We report a palladium-catalysed ethylene Heck reaction for the vinylation of aryl iodides using a tube-in-tube gas-liquid reactor. The flow process afforded various styrenes in short reaction times, employing moderate ethylene pressure. Georg Thieme Verlag Stuttgart · New York.
- Bourne, Samuel L.,Koos, Peter,Obrien, Matthew,Martin, Benjamin,Schenkel, Berthold,Baxendale, Ian R.,Ley, Steven V.
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scheme or table
p. 2643 - 2647
(2011/12/04)
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- A rapid and convergent synthesis of the integrastatin core
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The tetracyclic core of the integrastatin natural products has been prepared in a convergent and rapid manner. Our strategy relies upon a palladium(ii)-catalyzed oxidative cyclization to form the central [3.3.1]-dioxabicycle of the natural product core. Overall, the core has been completed in only 4 linear steps from known compounds.
- Tadross, Pamela M.,Bugga, Pradeep,Stoltz, Brian M.
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p. 5354 - 5357
(2011/09/13)
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- Preparation of conformationally constrained α2 antagonists: The bicyclo[3.1.0]hexane approach
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The aim of the research was to discover antagonists at α2 receptor subtypes potentially more selective than known compounds. We focused on new, conformationally restricted analogues of atipamezole. The key step in the synthetic sequences leading to target compounds relied on a rhodium-catalyzed intramolecular cyclopropanation reaction, the outcome of which varied with the nature of the diazo styrene precursor. Thus, depending on the substitution pattern of the double bond and the electronic properties of the diazo precursors, the cyclopropanes 2 or 7, naphtalenes 8, or pyrazolines 17 were formed. The byproducts 8 and 17 originated from different, nonoverlapping mechanisms. Among the racemates synthesized, three compounds (1a, 22a, and 22b) showed increased selectivity for α2A vs. α2B and α2C receptor subtypes, and consequently were prepared in enantiomerically pure form. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Bonnaud, Bernard,Funes, Philippe,Jubault, Nathalie,Vacher, Bernard
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p. 3360 - 3369
(2007/10/03)
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- Low-coordinated diphosphinidenecyclobutene ligands: A new entry for Stille cross-coupling of aryl bromides
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A sterically protected diphosphinidenecyclobutene/palladium system has been used to mediate the catalytic cross-coupling of aryl bromides with organostannanes. An air- and moisture-stable diphosphinidenecyclobutene ligand proved the efficiency and generality of this class of ligand for cross-coupling reactions.
- Gajare, Anil S.,Jensen, Rader S.,Toyota, Kozo,Yoshifuji, Masaaki,Ozawa, Fumiyuki
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p. 144 - 148
(2007/10/03)
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- Determining the scope of the lanthanide mediated, sequential hydroamination/C-C cyclization reaction: Formation of tricyclic and tetracyclic aromatic nitrogen heterocycles
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The scope of the lanthanide mediated, sequential hydroamination/C-C cyclization reaction was determined for the formation of tricyclic and tetracyclic aromatic nitrogen heterocycles. An array of ring sizes was explored to determine the diastereoselectivity. The electronic characteristics of the aromatic ring was also varied to determine how it affected the cascade reaction. It was found that the benzo[a]quinolizine and the pyrido[2,1,a]isoindolizine ring systems formed with the highest diastereoselectivity (>20:1), regardless of the electronic characteristics of the aromatic ring. Additionally, a tetracyclic indole nitrogen heterocycle was formed with a 2.3:1 diastereomeric ratio. A novel procedure for substrate preparation is also presented.
- Molander, Gary A.,Pack, Shawn K.
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p. 10581 - 10591
(2007/10/03)
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- Palladium-catalyzed coupling reaction of alkenylgalliums with aryl halides
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Treatment of aryl halides with alkenylgallium dichloride, prepared from GaCl3 and alkenylmagnesium bromide, in the presence of a catalytic amount of palladium provided cross-coupling products in good yields.
- Mikami, Satoshi,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1137 - 1139
(2007/10/03)
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- Palladium-Catalyzed Cross-Coupling Reaction of Organoindiums with Aryl Halides in Aqueous Media
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(matrix presented) Diaryl-, divinyl-, and dialkylindium proved to be stable in aqueous media and to undergo a palladium-catalyzed cross-coupling reaction with aryl halides in aqueous THF. Treatment of 3-iodophenol with diphenylindium compound, generated from indium trichloride and two equimolar amounts of a phenyl Grignard reagent, in aqueous media under palladium catalysis provided the corresponding coupling product in excellent yield. Divinyl- and diethlindium can be used for the coupling reaction in the presence of water. A wide range of functional groups, including a hydroxy group and a formyl group, are compatible with this reaction.
- Takami, Kazuaki,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
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p. 1997 - 1998
(2007/10/03)
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- Palladacycles as Precatalysts in Heck and Cross-Coupling Reactions
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A variety of pallaclacycles are shown to catalyze Heck alkenylations with similar efficiencies. The new oxapalladacycle 1 was shown to insert and transmetalate under mild conditions with n-butyl acrylate and vinyltributylstannane, respectively. This palladacycle acts as an active (pre)catalyst for cross-coupling and Heck reactions.
- Mu?oz, M. Paz,Martín-Matute, Belén,Fernández-Rivas, Carolina,Cárdenas, Diego J.,Echavarren, Antonio M.
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p. 338 - 342
(2007/10/03)
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- The conversion of 4-oxa-5-hexenyllithiums to 4-alken-1-ols: A novel [1,4]-wittig rearrangement
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4-Oxa-5-hexenyllithiums (2), which may be prepared from the corresponding 3-iodoalkyl vinyl ethers (1) by low-temperature lithium - iodine exchange, rearrange in high yield to 4-alken-1-ols (4) when warmed to room temperature. This transformation, which constitutes a [1,4]-Wittig rearrangement, is mediated by 5-exo-trig closure of 2 to a (2-tetrahydrofuranyl)methyllithium (3) followed by spontaneous ring opening to give 4.
- Bailey, William F.,Zarcone, Lyn M. J.
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p. 4425 - 4426
(2007/10/02)
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- Synthesis of spirononane system present in fredericamycin A
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Two different approaches for the construction of spirononane system present in fredericamycin A (1) have been reported.In the first approach (2-(β-haloethyl)phenyl)-indane-1,3-dione-methyl enolate (17) was subjected to trimethylsilyliodide reaction
- Rao, A. V. Rama,Rao, B. Venkateswara,Reddy, D. Reddappa
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p. 723 - 727
(2007/10/02)
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