- Selectivity in the cycloadditions of carbonyl ylides with glyoxylates: An approach to the zaragozic acids-squalestatins
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Reaction of diazodiketoester 8 with glyoxylates in the presence of catalytic rhodium(n) acetate generates 6,8-dioxabicyclo[3.2.1]octanes 9 and 11 in good yield. Elaboration of 9 provides a suitable alcohol 25 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 26 of the zaragozic acids-squalestatins. More substituted diazodiketoesters 36 and 40 also undergo highly regio- and diastereoselective cycloaddition with glyoxylates to give the cycloadducts 41,43 and 44. The Royal Society of Chemistry 2000.
- Hodgson, David M.,Bailey, James M.,Villalonga-Barber, Carolina,Drew, Michael G. B.,Harrison, Timothy
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Read Online
- Three-component reactions of tetranitromethane with olefins
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Three-component reactions of tetranitromethane with two different olefins taken in equimolar amounts are procedures fit for preparation of 3,3-dinitroisoxalidines of a mixed composition.
- Averina,Budynina,Ivanova,Grishin, Yu. K.,Gerdov,Kuznetsova,Zefirov
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Read Online
- Gas-phase reactions of nopinone, 3-Isopropenyl-6-oxo-heptanal, and 5-Methyl-5-vinyltetrahydrofuran-2-ol with OH, NO3, and Ozone
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In the troposphere, α-pinene, β-pinene, limonene, and linalool are mainly oxidized to pinonaldehyde, nopinone, 3-isopropenyl-6-oxoheptanal (IPOH), and 5-methyl-5-vinyltetrahydrofuran-2-ol (MVT), respectively. The rate constant of the reactions of nopinone, IPOH, and MVT with OH, NO3, and O3 were determined by long path FT-IR spectroscopy, and the oxidation products from the reactions between the OH radical and pinonaldehyde, nopinone, IPOH, and MVT were investigated using GC-MS and HPLC. The reaction rate constants (k) for the reactions have been determined at 740 ± 5 Torr and 298 ± 5 K, and a number of reaction products were identified. The rate constants obtained for the reactions with nopinone were kOH = (1.7 ± 0.2) x 10-11, kNO3 -15, and kO3, -21; for the reactions with IPOH were kOH = (1.1 ± 0.3) x 10-10, kNO3 = (2.6 ± 0.8) x 10-13, and kO3, = (8.3 ± 2.2) x 10-18; and for the reactions with MVT were kOH = (7.4 ± 0.9) x 10-11, kNO3 = (2.0 ± 0.9) x 10-14, and kO3, = (3.8 ± 0.8) x 10-18 (all units are in cm3 molecule-1 s-1, and uncertainties are given as two σ on the experimental data). From the results obtained in this investigation and previous studies, it was concluded that a typical atmospheric lifetime with respect to chemical reactions was only a few hours for pinonaldehyde, IPOH, and MVT but was much longer·for nopinone with a lifetime of about 10 h.
- Calogirou, Aggelos,Jensen, Niels R.,Nielsen, Claus J.,Kotzias, Dimitrios,Hjorth, Jens
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Read Online
- A Convenient Synthesis of 4-Oxoalkanals
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4-Oxoalkanals(γ-Ketoaldehydes), which are important intermediates for the syntheses of jasmonoids and pheromones, are prepared from the Michael reaction of nitroalkanes with acrolein catalyzed by tributylphosphine, followed by an electrochemical oxidative Nef reaction of the resultant 4-nitroalkanal ethylene acetals.
- Miyakoshi, Tetsuo
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Read Online
- Solvent effect on the rate and direction of furfural transformations during hydrogenation over the Pd/C catalyst
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The rate and directions of transformations during the liquid-phase hydrogenation of furfural with molecular hydrogen in the presence of the 5%Pd/C catalyst (at 423 K, 3 MPa) depend substantially on the chemical nature of the solvent. The main products of
- Belskaya, O. B.,Likholobov, V. A.,Mironenko, R. M.
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- Discovery of novel positive allosteric modulators of the α7 nicotinic acetylcholine receptor: Scaffold hopping approach
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The paper focuses on the scaffold hopping-based discovery and characterization of novel nicotinic alpha 7 receptor positive modulator (α7 nAChR PAM) ligands around the reference molecule (A-867744). First, substantial efforts were carried out to assess th
- Ledneczki, István,Tapolcsányi, Pál,Gábor, Eszter,Visegrády, András,Vass, Márton,éles, János,Holm, Patrik,Horváth, Anita,Pocsai, Anikó,Mahó, Sándor,Greiner, István,Krámos, Balázs,Béni, Zoltán,Kóti, János,Káncz, Anna E.,Thán, Márta,Kolok, Sándor,Laszy, Judit,Balázs, Ottilia,Bugovits, Gyula,Nagy, József,Vastag, Mónika,Szájli, ágota,Bozó, éva,Lévay, Gy?rgy,Lendvai, Balázs,Némethy, Zsolt
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- Atroposelective Synthesis of Axially Chiral N-Arylpyrroles by Chiral-at-Rhodium Catalysis
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A transformation of fluxional into configurationally stable axially chiral N-arylpyrroles was achieved with a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral-at-metal rhodium Lewis acid. Specifically, N-arylpyrroles were alkylated with N-acryloyl-1H-pyrazole electrophiles in up to 93 percent yield and with up to >99.5 percent ee, and follow-up conversions reveal the synthetic utility of this new method. DFT calculations elucidate the origins of the observed excellent atroposelectivity.
- Chen, Shuming,Han, Feng,Houk, K. N.,Ivlev, Sergei,Meggers, Eric,Xie, Xiulan,Ye, Chen-Xi
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supporting information
p. 13552 - 13556
(2020/06/05)
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- Synthesis of Two Key Fragments of the Complex Polyhalogenated Marine Meroterpenoid Azamerone
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A concise route toward two advanced fragments in the context of the total synthesis of the unique natural product azamerone is reported. Key synthetic features include the enantioselective synthesis of an epoxysilane and its Lewis-acid-induced cyclization and the installation of the pyridazine ring via a formylation/condensation sequence. This route provides strategic insights into the chemistry of phthalazinediols, facilitating synthetic approaches toward this class of natural products.
- Schnell, Simon D.,Linden, Anthony,Gademann, Karl
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supporting information
p. 1144 - 1147
(2019/05/16)
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- Domino Carbopalladation/C-H Activation as a Quick Access to Polycyclic Frameworks
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A new type of domino reaction for synthesis of heterocycles fusing the important bioactive cores, such as oxindole, indoline, and isoquinoline, is presented. Upon exposure to the very common palladium catalyst, the conceptually designed N-alkenyl iodobiaryls undergo a sequential carbopalladation/C-H activation to build polycyclic frameworks. These novel unique frameworks may provide structure sources in fragment-based drug discovery.
- Saha, Nemai,Wang, Haiwen,Zhang, Shengyi,Du, Yongliang,Zhu, Daqian,Hu, Yumin,Huang, Peng,Wen, Shijun
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supporting information
p. 712 - 715
(2018/02/09)
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- NOVEL PROCESS FOR PREPARING SYNTHESIS INTERMEDIATES USING PRODUCTS OF NATURAL ORIGIN AND USE OF THE INTERMEDIATES OBTAINED
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Disclosed is a process for preparing a product of formula I: wherein the reaction is catalyzed both by thiamine or a thiamine salt and by ascorbic acid in a form which is free or salified or an organic acid salt of an alkaline metal, preferably sodium acetate, potassium tartrate, sodium succinate, or a reductone, preferably 2-hydroxypropanedial or 2,3-dihydroxycyclopent-2-ene-1-one in an organic solvent.
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Paragraph 0231
(2017/12/15)
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- Proline-Catalyzed Knoevenagel Condensation/[4+2] Cycloaddition Cascade Reaction: Application to Formal Synthesis of Averufin
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A remarkable proline-catalyzed method for the construction of biologically interesting oxygen-bridged tricyclic ketal skeletons was uncovered by starting from a variety of readily available cyclic 1,3-diketones and either 1,4- or 1,5-dicarbonyl substrates. The approach, which mimics a biosynthetic Knoevenagel condensation/[4+2] cycloaddition sequence, establishes a viable synthetic strategy for the efficient formal synthesis of averufin. A remarkable proline-catalyzed Knoevenagel condensation/[4+2] cycloaddition cascade reaction was uncovered for the construction of biologically interesting tricyclic ketal skeletons. This approach mimics a biosynthetic sequence and establishes a viable synthetic strategy for the efficient formal synthesis of averufin.
- Tan, Haibo,Chen, Xinzheng,Chen, Huiyu,Liu, Hongxin,Qiu, Shengxiang
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supporting information
p. 4956 - 4963
(2015/08/03)
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- Efficient and Selective Cu/Nitroxyl-Catalyzed Methods for Aerobic Oxidative Lactonization of Diols
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Cu/nitroxyl catalysts have been identified that promote highly efficient and selective aerobic oxidative lactonization of diols under mild reaction conditions using ambient air as the oxidant. The chemo- and regioselectivity of the reaction may be tuned by changing the identity of the nitroxyl cocatalyst. A Cu/ABNO catalyst system (ABNO = 9-azabicyclo[3.3.1]nonan-N-oxyl) shows excellent reactivity with symmetrical diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl) displays excellent chemo- and regioselectivity for the oxidation of less hindered unsymmetrical diols. These catalyst systems are compatible with all classes of alcohols (benzylic, allylic, aliphatic), mediate efficient lactonization of 1,4-, 1,5-, and some 1,6-diols, and tolerate diverse functional groups, including alkenes, heterocycles, and other heteroatom-containing groups.
- Xie, Xiaomin,Stahl, Shannon S.
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supporting information
p. 3767 - 3770
(2015/04/14)
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- Fukuyama reduction and integrated thioesterification/fukuyama reduction of thioesters and acyl chlorides using continuous flow
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Fukuyama reduction of thioesters has been achieved using a polymer-supported Pd[0] catalyst (Pd/XAD-4), and continuous flow conditions. The generality of this reaction is good with a range of aldehydes prepared in excellent yields. In addition, an integrated multistep thioesterfication/ Fukuyama reduction has been developed that allows acyl chlorides to be directly converted to the corresponding aldehydes. Integral to this process is the use of polymer-supported amine and isocyanate reagents to achieve thioesterification and scavenge unreacted thiol. In addition, catch-and-release purification has been employed to enable isolation of the aldehyde from silylthioether byproducts without the need for chromatographic purification.
- Asadi, Mousa,Bonke, Shannon,Polyzos, Anastasios,Lupton, David W.
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p. 2070 - 2074
(2014/06/24)
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- A catalytic enantioselective tandem allylation strategy for rapid terpene construction: Application to the synthesis of pumilaside aglycon
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Catalytic enantioselective 1,2-diboration of 1,3-dienes followed by cascade allylborations with dicarbonyls provides rapid entry into carbocyclic reaction products. The stereochemical course of this reaction was studied along with its application in the synthesis of pumilaside aglycon.
- Ferris, Grace E.,Hong, Kai,Roundtree, Ian A.,Morken, James P.
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supporting information
p. 2501 - 2504
(2013/03/29)
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- Monoenomycin: A simplified trienomycin A analogue that manifests anticancer activity
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Macrocyclic natural products are a powerful class of leadlike chemical entities. Despite commonly violating Lipinski's "rule of 5", these compounds often demonstrate superior druglike physicochemical and pharmacokinetic attributes when compared to their acyclic counterparts. However, the elaborate structural architectures of such molecules require rigorous synthetic investigation that complicates analogue development and their application to drug discovery programs. To circumvent these limitations, a conformation-based approach using limited structure-activity relationships and molecular modeling was implemented to design simplified analogues of trienomycin A, in which the corresponding analogues could be prepared in a succinct manner to rapidly identify essential structural components necessary for biological activity. Trienomycin A is a member of the ansamycin family of natural products that possesses potent anticancer activity. These studies revealed a novel trienomycin A analogue, monoenomycin, which manifests potent anticancer activity.
- Brandt, Gary E. L.,Blagg, Brian S. J.
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supporting information; experimental part
p. 735 - 740
(2011/12/02)
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- The gas-phase ozonolysis of α-humulene
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α-Humulene contains three double bonds (DB), and after ozonolysis of the first DB the first-generation products are still reactive towards O 3 and produce second- and third-generation products. The primary aim of this study consisted of identifying the products of the three generations, focusing on the carboxylic acids, which are known to have a high aerosol formation potential. The experiments were performed in a 570 litre spherical glass reactor at 295 K and 730 Torr. Initial mixing ratios were 260-2090 ppb for O3 and 250-600 ppb for α-humulene in synthetic air. Reactants and gas-phase products were measured by in situ FTIR spectroscopy. Particulate products were sampled on Teflon filters, extracted with methanol and analyzed by LC-MS/MS-TOF. Using cyclohexane (10-100 ppm) as an OH-radical scavenger and by monitoring the yield of cyclohexanone by PTR-MS, an OH-yield of (10.5 ± 0.7)% was determined for the ozonolysis of the first DB, and (12.9 ± 0.7)% of the first-generation products. The rate constant of the reaction of O3 with α-humulene is known as k0 = 1.17 × 10-14 cm3 molecule-1 s-1 [Y. Shu and R. Atkinson, Int. J. Chem. Kinet., 1994, 26, 1193-1205]. The reaction rate constants of O3 with the first-generation products and the second-generation products were, respectively, determined as k1 = (3.6 ± 0.9) × 10-16 and k2 = (3.0 ± 0.7) × 10-17 cm3 molecule-1 s -1 by Facsimile-simulation of the observed ozone decay by FTIR. A total of 37 compounds in the aerosol phase and 5 products in the gas phase were tentatively identified: 25 compounds of the first-generation products contained C13-C15 species, 9 compounds of the second-generation products contained C8-C11 species, whereas 8 compounds of the third-generation products contained C4-C6 species. The products of all three generations consisted of a variety of dicarboxylic-, hydroxy-oxocarboxylic- and oxo-carboxylic acids. The formation mechanisms of some of the products are discussed. The residual FTIR spectra indicate the formation of secondary ozonides (SOZ) in the gas phase, which are formed by the intramolecular reaction of the Criegee moiety with the carbonyl endgroup. These SOZ revealed to be stable over several hours and its formation was shown not to be affected by the addition of Criegee-radical scavengers such as HCOOH or H2O. This suggests that in the ozonolysis of α-humulene at atmospheric pressures the POZ will decompose rapidly, and that a large fraction of the formed exited Criegee Intermediate will be stabilized to form stable SOZ, while the formation of OH-radicals via the hydroperoxide channel will be a minor process. the Owner Societies.
- Beck,Winterhalter,Herrmann,Moortgat
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experimental part
p. 10970 - 11001
(2012/01/02)
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- B-alkylcatecholborane-mediated tandem radical conjugated addition-aldol cyclization
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Image Presented A one-pot procedure involving radical conjugate addition of B-alkylcatecholboranes to enones followed by intramolecular aldol reaction is reported. Application to the stereoselective synthesis of monocyclic and bicyclic products with up to
- Beauseigneur, Alice,Ericsson, Cecilia,Renaud, Philippe,Schenk, Kurt
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supporting information; experimental part
p. 3778 - 3781
(2011/02/28)
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- Supported gold nanoparticles as a reusable catalyst for synthesis of lactones from diols using molecular oxygen as an oxidant under mild conditions
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The oxidative lactonization of various diols using molecular oxygen as a primary oxidant can be efficiently catalyzed by hydrotalcite-supported Au nanoparticles (Au/HT). For instance, lactonization of 1,4-butanediol gave γ-butyrolactone with an excellent turnover number of 1400. After lactonization, the Au/HT can be recovered by simple filtration and reused without any loss of its activity and selectivity.
- Mitsudome, Takato,Noujima, Akifumi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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experimental part
p. 793 - 797
(2010/04/23)
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- Organocatalytic enantioselective total synthesis of (-)-arboricine
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The tetracyclic indole alkaloid (-)-arboricine has been prepared using an asymmetric organocatalytic Pictet - Spengler reaction as the key step followed by a diastereoselective Pd-catalyzed iodoalkene/enolate cyclization. The absolute stereochemistry was unequivocally proven by X-ray crystallographic analysis and appeared to be opposite to the published structure in the original paper.
- Wanner, Martin J.,Boots, Rowan N.A.,Eradus, Bram,De Gelder, Rene,Van Maarseveen, Jan H.,Hiemstra, Henk
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supporting information; scheme or table
p. 2579 - 2581
(2009/10/23)
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- Sunlight oxidation of alkyl aryl tellurides to the corresponding carbonyl compounds: A new carbonyl precursor
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Alkyl aryl tellurides were efficiently transformed to the corresponding carbonyl compounds by photo-oxidation with sunlight without affecting various functional groups in the alkyl moiety. The tellurides can be used as a new carbonyl precursor, and the photolysis can be conducted without special equipment for light sources.
- Ouchi, Akihiko,Hyugano, Takeshi,Liu, Chuanxiang
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supporting information; experimental part
p. 4870 - 4873
(2010/01/06)
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- Facile photochemical transformation of alkyl aryl selenides to the corresponding carbonyl compounds by molecular oxygen: Use of selenides as masked carbonyl groups
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(Chemical Equation Presented) Alkyl aryl selenides with and without functional groups on the alkyl group were transformed efficiently into the corresponding carbonyl compounds, particulary primary alkyl aryl selenides in good yields, by a simple photolysis in the presence of air or oxygen. This transformation can be conducted without protection of functional groups. The yield of carbonyl compounds was much affected by the solvent viscosity, reaction temperature, concentration of dissolved oxygen in the solvents, wavelength of light, and structure of the aryl substituents. The present study indicates that aryl selenides can be considered as a masked carbonyl group that can be easily converted to a carbonyl group by very mild reaction conditions even in the presence of various unprotected functional groups. Therefore, this functional group transformation can be used as an important tool in organic synthesis due to its simplicity and mild reaction condition.
- Hyugano, Takeshi,Liu, Suyou,Ouchi, Akihiko
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supporting information; scheme or table
p. 8861 - 8866
(2009/04/05)
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- AZAINDOLE COMPOUNDS AND USE THEREOF AS PHOSPHOLIPASE-A2 INHIBITORS
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Indole and indole-related compounds, compositions and methods are disclosed. The compounds of the invention are useful as phospholipase inhibitors. The compounds and compositions of the invention are useful for treatment of phospholipase-related conditions, such as insulin-related, weight-related and/or cholesterol-related conditions in an animal subject.
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Page/Page column 85
(2008/06/13)
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- PHOSPHOLIPASE INHIBITORS, INCLUDING MULTI-VALENT PHOSPHOLIPASE INHIBITORS, AND USE THEREOF, INCLUDING AS LUMEN-LOCALIZED PHOSPHOLIPASE INHIBITORS
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The present invention provides methods and compositions for the treatment of phospholipase-related conditions. In particular, the invention provides a method of treating insulin-related, weight-related conditions and/or cholesterol-related conditions in an animal subject. The method generally involves the administration of a non-absorbed and/or effluxed phospholipase A2 inhibitor that is localized in a gastrointestinal lumen.
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Page/Page column 229
(2010/11/27)
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- Multivalent indole compounds and use thereof as phospholipase-A2 inhibitors
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Indole and indole-related compounds, compositions and methods are disclosed. The compounds of the invention are useful as phospholipase inhibitors. The compounds and compositions of the invention are useful for treatment of phospholipase-related conditions, such as insulin-related, weight-related and/or cholesterol-related conditions in an animal subject.
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Page/Page column 122-123
(2010/11/27)
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- Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: Synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles
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N-Alkylation of 4,5-dihydroimidazoles with alkene-containing bromomethyl ketones and treatment of the so-formed 4,5-dihydroimidazolium ions with DBU gives rise to an intramolecular 1,3-dipolar cycloaddition reaction that affords (via a reaction cascade involving eliminative ring-opening, recyclisation and prototropic tautomerism) unexpected hexahydropyrrolo[1,2,3-de]quinoxaline products. Steric bulk in both the dihydroimidazole and the dipolarophile allows isolation of an imidazo[1,2-a]indole, the initial product of cycloaddition. When the bromomethyl ketone contains no other functionality, or when cycloaddition is inhibited due to steric constraints, the dihydroimidazolium ion undergoes ring-opening hydrolysis followed by recyclization of the exposed amino ketone to afford either 3-alkyl-1-formylpiperazine-2-ones or 3-aryl-1-formyl-1,4,5,6- tetrahydropyrazines. The Royal Society of Chemistry 2006.
- Lory, Pedro M.J.,Jones, Raymond C.F.,Iley, James N.,Coles, Simon J.,Hursthouse, Michael B.
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p. 3155 - 3165
(2008/03/12)
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- Dual molecules containing a peroxide derivative, synthesis and therapeutic applications thereof
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The invention relates to dual molecules formed from coupling products complying with the formula wherein A represents a residue of molecule with anti-malarial activity, Y1 and Y2, represent a linear or ramified alkylene chain at C1 t
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Page/Page column 12
(2008/06/13)
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- The samarium(II)-mediated intermolecular couplings of ketones and β-alkoxyacrylates: A short asymmetric synthesis of an antifungal γ-butyrolactone
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The samarium(II) iodide-mediated coupling of ketones with β-alkoxyacrylates gives β-hydroxy-γ-butyrolactones in moderate yield. The process has been applied to the asymmetric synthesis of an antifungal, γ-butyrolactone natural product.
- Kerrigan, Nessan J.,Upadhyay, Tejas,Procter, David J.
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p. 9087 - 9090
(2007/10/03)
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- Borane-mediated aldol cycloreduction of monoenone monoketones: Diastereoselective formation of quaternary centers
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Exposure of monoenone monoketones to catecholborane in THF at ambient temperature results in tandem 1,4-reduction-aldol cyclization. For aromatic and heteroaromatic enones, six-membered cyclic aldol products are formed in excellent yield with high levels of syn diastereoselectivity. Five-membered ring formation proceeds less readily, but the yield of cyclized product is improved through introduction of Rh(I) salts.
- Huddleston, Ryan R.,Cauble, David F.,Krische, Michael J.
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- Switching between Novel Samarium(II)-Mediated Cyclizations by a Simple Change in Alcohol Cosolvent
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(Equation Presented) γ,δ-Unsaturated ketones undergo two very different stereoselective cyclization reactions mediated by samarium(II) iodide depending upon the alcohol cosolvent used in the reaction. Switching between an unprecedented aldol spirocyclizat
- Hutton, Thomas K.,Muir, Kenneth W.,Procter, David J.
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p. 4811 - 4814
(2007/10/03)
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- Direct hydrogenation of carboxylic acids to corresponding aldehydes catalyzed by palladium complexes
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A variety of carboxylic acids can be directly hydrogenated into the corresponding aldehydes in high yields by using homogeneous catalysts such as [Pd(PPh3)4] or combination of Pd(OAc)2 with tertiary phosphines in the presence of an excess amount of 2,2-dimethylpropionic anhydride (pivalic anhydride). As a typical example, octanoic acid can be convened into octanal in 99% yield in 3 h at 80 °C under 3.0 MPa of H2 in acetone in the presence of pivalic anhydride and a catalyst system composed of Pd(OAc)2 + 5P(p-tol)3. Such hydrogenation is widely applicable to various aliphatic, aromatic, and heterocyclic carboxylic acids as well as to di- and tribasic carboxylic acids. The process allows the presence of other functional groups such as ketonic carbonyl, nitrile, and ester groups and even internal C=C bonds. Heterogeneous palladium catalyst such as palladium on carbon also showed some catalytic activities.
- Nagayama,Shimizu,Yamamoto
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p. 1803 - 1815
(2007/10/03)
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- Gas-Phase Reactions of 1,2-Dimethylcyclopentene and of 2,6-Heptanedione with Ozone: Unprecedented Formation of an Ozonide by Ozone Treatment of a Diketone
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Gas-phase ozonizations of 1,2-dimethylcyclopentene (1) and of 2,6-heptanedione (5) afforded in each case dimethylcyclopentene ozonide (2) in low yields. In the ozonization of 1, diketone 5 was formed as the single major product, along with nine "abnormal" ozonolysis products which were formed by oxidative cleavage of carbon-carbon single bonds.
- Griesbaum, Karl,Miclaus, Vasile,Jung, Chan,Quinkert, Ralf-Olaf
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p. 627 - 629
(2007/10/03)
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- Sequenced Reactions with Samarium(II) Iodide. Domino Epoxide Ring-Opening/Ketyl Olefin Coupling Reactions
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A new sequential reductive coupling process promoted by samarium(II) iodide is described. Cascade epoxide ring opening and ketyl radical olefin cyclization leads to a variety of cis-1,3-cyclopentanediols and cis-1,3-cyclohexanediols in good yields and with high diastereoselectivity.
- Molander, Gary A.,Losada, Carlos Del Pozo
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p. 2935 - 2943
(2007/10/03)
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- Oxidation of alcohols by quinolinium chlorochromate
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Quinolinium chlorochromate (QCC) is shown to be an efficient reagent for the selective oxidation of primary and secondary alcohols to aldehydes and ketones respectively.
- Srinivasan,Ramesh,Madhulatha,Balasubramanian
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p. 480 - 481
(2007/10/03)
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- Kinetics and products of the gas-phase reactions of 6-methyl-5-hepten-2-one and trans-cinnamaldehyde with OH and NO3 radicals and O3 at 296 ± 2 K
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6-methyl-5-hepten-2-one is an atmospheric reaction product of the biogenic emission linalool, and trans-cinnamaldehyde is a model compound for dicarbonyls formed from the OH radical-initiated reaction of naphthalene. These carbonyl compounds react in the atmosphere, and photoloysis and the gas-phase reactions with OH radicals, NO3 radicals, and O3 have been investigated. Using relative rate methods, the respective rate constants were obtained for the OH radical, NO3 radical, and O3 reactions.
- Smith,Rigler,Kwok,Atkinson
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p. 1781 - 1785
(2007/10/03)
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- 4-Isopropyl-2-oxazolin-5-one anion as masked umpoled synthon for both formyl and hydroxycarbonyl anions: Generation, reactivity and synthetic applications
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The anion of the title compound, simply generated in the presence of catalytic amount of triethylamine, reacts with both common electrophilic olefins and aldehydes to give moderate to good yield of Michael or aldol adducts respectively. Mild acid treatment of these adducts at ambient temperature serves to demask the aldehyde function, allowing one to consider the anion of 1 as a nucleophilic acylating equivalent of formaldehyde. On the other hand, the same anion of 1 may act as a masked umpoled synthon for a hydroxycarbonyl anion since its aldol adducts with aldehydes undersent concomitant isomerization and ring cleavage under mild basic conditions producing dipeptides which could be hydrolyzed to give the corresponding carboxylic acids. Synthetic applications of this chemistry in the area of sugar, aminosugar and non-proteinogenic aminoacid derivatives are discussed.
- Barco, Achille,Benetti, Simonetta,De Risi, Carmela,Pollini, Gian P.,Spalluto, Giampiero,Zanirato, Vinicio
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p. 4719 - 4734
(2007/10/03)
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- A general synthesis of (+)-γ-substituted γ-butyrolactones using a kinetic alkylation-ozonolysis procedure
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A synthesis of (±)-γ-substituted γ-butyrolactones is described in which the key intermediates, γ-ketoesters, are prepared from the readily available 6-methyl-5-hepten-2-one using a kinetic alkylation-ozonolysis procedure; the method allows terminal ester and Z-alkene groups to be incorporated into the side-chain and thus can be used for the synthesis of (+)-γ-jasmolactone as well as other naturally occurring lactones.
- Gavin,Geraghty
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p. 1351 - 1361
(2007/10/02)
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- Synthesis of New Chiral Phosphinephosphites Having 2-Diphenylphosphinobiphenyl-2'-yl Backbone and Their Use in Rh(I)-Catalyzed Asymmetric Hydroformylations
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New chiral phosphinephosphites (R)-(5,5'-dichloro-2-diphenylphosphino-4,4',6,6'-tetramethylbiphenyl-2'-yl)(S)-1,1'-binaphthalen-2,2'-diyl)phosphite and its enantiomer (S,R)-BIPHEMPHOS have been synthesized from 5,5'-dichloro-4,4',6,6'-tetramethyl-2,2'-biphenyldiol in enantiomerically pure form.Their Rh(I) complexes have been shown to be highly efficient catalysts for asymmetric hydroformylations of a variety of olefinic substrates.The corresponding phosphinephosphites derived from 2,2'-biphenyldiol were also tested as ligands for asymmetric hydroformylation.
- Higashizima, Takanori,Sakai, Nozomu,Nozaki, Kyoko,Takaya, Hidemasa
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p. 2023 - 2026
(2007/10/02)
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- Synthesis of Two 2-(Oxoalkyl)-3-methyl-2-cyclopentenones
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Reported here are the preparations of 2-(2-oxopropyl)-3-methyl-2-cyclopentenone and the 2,2-dimethyl-1,3-propanediol ketal of 2-(3-oxobutyl)-3-methyl-2-cyclopentenone.A reagent for the convenient preparation of such cyclic ketals is described.
- Sant, Milind P.,Smith, William B.
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p. 5479 - 5481
(2007/10/02)
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- Neighboring group participation in Lewis acid-promoted [3 + 4] and [3 + 5] annulations. The synthesis of oxabicyclo[3.n.1]alkan-3-ones
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Lewis acids are employed as catalysts in the annulation of 1,4- and 1,5-dicarbonyl dielectrophiles with bis(trimethylsilyl) end ethers of β-diketones and β-keto esters. A variety of 2-(alkoxycarbonyl)-m-oxabicyclo[3.n.1]alkan-3-ones can be constructed by this process in which two new carbon-carbon bonds are generated. Unusually high regiocontrol is observed, and good to excellent stereochemical control can be achieved at virtually every position on the new carbocycles. Intramolecular neighboring group participation is proposed to explain the unusually high selectivities attained in the annulation reaction.
- Molander, Gary A.,Camera, Kimberly O.
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p. 830 - 846
(2007/10/02)
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- 4-Isopropyl-2-oxazolin-5-one anion as a new convenient formyl anion equivalent for conjugate addition and aldol reactions
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The anion of the title compound, simply generated in the presence of catalytic amount of triethylamine, acts as nucleophilic acylating equivalent of formaldehyde reacting with both common electrophilic olefins or aldehydes to give moderate to good yield of Michael or aldol adducts respectively, which are easily hydrolized by dilute acid at ambient to temperature to afford the corresponding aldehydes.
- Barco, Achille,Benetti, Simonetta,De Risi, Carmela,Pollini, Gian P.,Spalluto, Giampiero,Zanirato, Vinicio
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p. 3907 - 3910
(2007/10/02)
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- Marschalk reaction approaches for the synthesis of (+/-)-4-demethoxydaunomycinone
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Marschalk reaction on leucoquinizarin (10) with the appropiate aldehydes 6 or 8 affords the alkylated quinizarin derivatives 11b and 13b respectively which are succesfully elaborated to 4-demethoxy-7,9-dideoxydaunomycinone (4) Marschalk reaction of 10 with bromoaldehyde 9, directly gives 4. 2-Formylquinizarin (21) and levulinic aldehyde 7 under the Marschalk reaction gives 8-acetyl-6,11-dihydroxy-9,10-dihydro-5,12-naphthacenedione (22), a useful intermediate for the asymmetric synthesis of (-)-4-demethoxy-7-deoxydaunomycinone.
- Ayyangar, N R,Argade, A B,Mehendale, A R,Deshpande, V H
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- A new route to trans 2,5-dialkylpyrrolidines
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Benzylic amines 8 react with ketoenoates 7 yielding, after reduction of the primary adducts, 2,5-dialkylpyrrolidines 9 (trans isomer predominating). This reaction has been applied to the synthesis of trans 2-heptyl-5-ethylpyrrolidine, a component of the venom of fire ant (Solenopsis punctaticeps).
- Dumas, Franoise,D'Angelo, Jean
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p. 2005 - 2008
(2007/10/02)
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- Reaction of Carbonyl Compounds with Ethyl Lithiodiazoacetate. Studies Dealing with the Rhodium(II)-Catalyzed Behavior of the Resulting Adducts
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The carbenoid intermediate derived by treating ethyl 2-diazo-4-phthalimidobutyrate with rhodium(II) octanoate undergoes transannular cyclization onto the adjacent imido carbonyl group.The resulting cyclic carbonyl ylide diploe was trapped with several dipolarophiles.In an attempt to prepare related substrates for cyclization studies, the reaction of ethyl lithiodiazoacetate with various aldehydes and ketones was studied.Treatment of the α-diazo-β-hydroxy ester derived from acetone or cyclopentanone with rhodium(II) octanoate gave rise to a β-keto ester.The exclusive phenyl shift encountered with acetophenone is in keeping with migration to an electron-deficient center.The reaction works well with acrolein, leading to high yields of 3-oxo-4-pentenoate.The 1,2-hydrogen shift pathway was found to proceed much faster than intramolecular cyclopropanation.Dehydration of the α-diazo-β-hydroxy esters generates vinyl diazo esters, which readily cyclize to 1H-pyrazoles on thermolysis.
- Padwa, Albert,Kulkarni, Yashwant S.,Zhang, Zhijia
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p. 4144 - 4153
(2007/10/02)
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- PALLADIUM(0) CATALYZED REACTIONS OF 1,4-EPIPEROXIDES
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The Pd(PPh3)4 catalyzed reaction of 2,3-saturated and 2,3-unsaturated 1,4-epiperoxides proceeds by courses markedly different from those of the previously reported transition metal catalyses.The Pd(0)-promoted reaction of 2,3-saturated epiperoxides gives the corresponding 4-hydroxy ketones and 1,4-diols as the major products.From 2,3-dedihydroepiperoxides are formed the corresponding 4-hydroxy enones, syn-1,2;3,4-diepoxides, and 1,4-diols.The results are interpreted in terms of competing Pd(0)/Pd(II) exchange mechanisms.Exposure of prostaglandin (PG) H2 methyl esterto Pd(PPh3)4 produces a mixture of methyl esters of PGD2, PGE2, PGF2α, and (5Z,8E,10E,12S)-12-hydroxy-5,8,10-heptadecatrienoic acid.
- Suzuki, Masaaki,Oda, Yoshihisa,Hamanaka, Nobuyuki,Noyori, Ryoji
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p. 517 - 535
(2007/10/02)
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- Ozonolyses of 1-Methylcyclopentene, 1-Methylcyclobutene, 5-Hexen-2-one, and Natural Rubber in the Presence of Methanol
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Ozonolyses of 1-methylcyclopentene (8a) and of 1-methylcyclobutene (8b) in methanol proceeded in each case in the two possible directions.The resulting methoxyperoxides 13 and 14 afforded the corresponding peroxyhemiacetals 15 and 19 by intramolecular reactions of the OOH with the corresponding carbonyl groups.Ozonolysis of 1-methylcyclobutene (8b) additionally gave the corresponding ozonide 17b and 2-hydroperoxy-5-methoxy-2-methyl- as well as 5-hydroperoxy-2-methoxy-2-methyltetrahydrofuran (16b and 18b).The mode of formation of these hydroperoxy compounds has been elucidated by ozonolyses of 5-hexen-2-one (25) and of natural rubber (28) in the presence of methanol. - Keywords: Cycloalkenes, 1-methyl- / Ozonolysis / Peroxyhemiacetals, cyclic / Rubber, natural / Tetrahydrofurans, 2-hydroperoxy-
- Griesbaum, Karl,Kiesel, Gilbert
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p. 145 - 150
(2007/10/02)
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- 1,4-Ketoaldehydes via Michael-Addition of deprotonated Aldimines to 2-(N-Methylanilino)-acrylonitrile
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A new method for the synthesis of the title compounds by a one-pot three component coupling reaction is described.It consists of the reaction of an enolateanion- and an enolcation-equivalent with subsequent alkylation of an acylanion-equivalent.
- Ahlbrecht, Hubertus,Daacke, Axel von
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- Anhydrous Iron(III) Chloride Dispersed on Silica Gel; III. A Convenient and Mild Reagent for Deacetalization in Dry Medium
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Acetals of various structures are conveniently cleaved under mild conditions by anhydrous iron(III) chloride dispersed on silica gel in the absence of any solvent.
- Fadel, Antoine,Yefsah, Ramdane,Salauen, Jacques
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- OZONOLYSIS OF ALKENES AND REACTIONS OF POLYFUNCTIONAL COMPOUNDS. XXIX. SYNTHESIS OF ACYCLIC (Z)-1,5-POLYENE ISOPRENOID KETO ACETALS
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A convenient method was developed for the synthesis of acyclic (Z)-1,5-polyene isoprenoid keto acetals on the basis of the partial ozonolysis of regular (Z)-1,4-polyisoprene with subsequent reduction of the peroxides to ω-acetylaldehydes and selective protection of the formyl group.The individual dimethyl acetals of (Z)-1,5-polyene isoprenoid ω-acetylaldehydes with 1-5 (Z)-isoprene units were isolated by vacuum distillation of the mixture of isoprenologs.
- Odinokov, V. N.,Ignatyuk, V. K.,Krivonogov, V. P.,Tolstikov, G. A.
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p. 848 - 851
(2007/10/02)
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