- Silver-Catalyzed Three-Component 1,1-Aminoacylation of Homopropargylamines: α-Additions for Both Terminal Alkynes and Isocyanides
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The reaction of secondary homopropargylamines, isocyanides, and water in the presence of a catalytic amount of silver acetate and subsequent purification by chromatography on silica gel afforded substituted proline amides in good to excellent yields. Primary homopropargylamines underwent a cyclizative Ugi–Joullié three-component reaction with isocyanides and carboxylic acids to afford functionalized N-acyl proline amides. High diastereoselectivity was observed in the synthesis of 4-alkoxy and 4,5-disubstituted proline derivatives. This work represents the first examples of a three-component cyclizative 1,1-aminoacylation of terminal alkynes.
- Tong, Shuo,Piemontesi, Cyril,Wang, Qian,Wang, Mei-Xiang,Zhu, Jieping
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supporting information
p. 7958 - 7962
(2017/06/27)
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- Azo-coupling and reduction of cyclopropanediazonium ions in the reactions with polyhydroxyarenes and aminophenols
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A reaction of cyclopropanediazonium ion, generated by decomposition of N-cyclopropyl-N-nitrosourea upon treatment with potassium or cesium carbonates, with various poly-hydroxyarenes and aminophenols has been studied. The reaction of azo-coupling proceeds with phloroglucinol, resorcinol, 3-methoxy- and 3-aminophenol giving rise to mono-, bis-, and tris(cyclopropylazo)arenes as the major products. Oxidizable phenols such as hydro-quinone, 2-methoxy-, 4-amino-, and 2-aminophenol give products of radical transformations with participation of cyclopropyl radical.
- Shulishov,Klimenko,Korolev,Kostyuchenko,Okonnishnikova,Tomilov
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experimental part
p. 1703 - 1711
(2011/04/23)
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- Palladium-mediated intramolecular C-N bond formation involving allyl substituted pyridines. Application to a novel strategy for the synthesis of the skeleton of berberinium derivatives
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The insertion of allenes in the Pd-C σ bond of cyclopalladated pyridine derivatives afforded (η3-allyl) Pd complexes. The ideally located imine unit reacted selectively with the allyl functionality to yield a series of new cationic heterocycles. The process opened the route to a novel strategy for the synthesis of berberiniums, a class of molecules of pharmacological interest.
- Chengebroyen, Jaganaiden,Linke, Myriam,Robitzer, Mike,Sirlin, Claude,Pfeffer, Michel
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p. 313 - 321
(2007/10/03)
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- IMIDAZOLE DERIVATIVES AND MEDICINAL COMPOSITION THEREOF
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An imidazole derivative represented by the following general formula (I), a salt thereof, a hydrate thereof or a solvate thereof. (Symbols in the formula have the following meanings. A: a lower alkylene group unsubstituted or substituted with a hydroxyl group, an aryl group, a lower alkylidene group or an oxo group (=O), X: a methylene group or a group represented by a formula -NR2-, R1: a hydrogen atom, a lower alkyl group or an aralkyl group, R2: a hydrogen atom or a lower alkyl group). The compounds have a steroid 17-20 lyase inhibiting activity and is useful in treating and preventing diseases such as prostate cancer, benign prostatic hyperplasia, breast cancer, mastopathy, hysteromyoma, endometriosis and the like.
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- Synthetic Microbial Chemistry, XXVI. - Absolute Configuration of (+)-Xanthocidin as Determined by the Synthesis of Its Enantiomers of Known Stereochemistry
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The absolute configuration of the antibiotic (+)-xanthocidin (4,5-dihydroxy-5-isopropyl-4-methyl-2-methylene-3-oxocyclopentane-1-carboxylic acid, 1) was shown to be 1R,4S,5S by the synthesis of its enantiomers.Lipase AK (Amano) was used for the key resolution step, and the absolute configuration of the resolved intermediate (+)-16 was determined by X-ray analysis of its (1S)-camphanic ester (+)-20. - Key Words: Antibiotics / Asymmetric acylation / Lipases / Streptomyces xanthocidicus / Xanthocidin
- Mori, Kenji,Horinaka, Akio,Kido, Masaru
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p. 817 - 826
(2007/10/02)
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- Kinetic Investigation of the Reactions of Methyl Radicals with But-2-yne
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The reactions of methyl radicals with but-2-yne have been studied in a greaseless static vessel in the temperature range 543...583 K.The methyl radicals were generated by thermolysis of azomethane (initial pressures 2.66 kPa and 3.19 kPa) in mixtures with the alkyne (initial pressures 0...7.8 kPa).The primary steps are H-abstractions producing 3-methylpropargyl radicals and additions to the triple bond forming trimethylvinyl radicals.Both radicals were stabilized by hydrogen abstraction from the parent compounds and by combination processes. The temperature dependence of the rate constant k2 for the addition reactio n can be expressed by the equation k2 = 108.65+/-0.20exp(-40300 +/- 1300)Jmol-1/RT M-1s-1 For the rate constant of hydrogen abstraction a value of k1 = 1.65 . 105 M-1s-1 at 573 K was estimated.Therefore the H-abstraction proceeds about two times faster than the addition reaction.
- Claus, P.,Marquardt, M.,Trung, Tran Kim,Scherzer, K.
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p. 533 - 539
(2007/10/02)
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- LA PHOTOCHIMIE DE L'ISOPRENE GAZEUX DANS LA REGION DE L'ULTRAVIOLET TRES LOINTAIN
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Yields of various products have been measured in the photolysis of isopropene at 184.9, 213.8, and 228.8 nm and at pressures between 1 and 400 Torr.At each wavelength, the major process is the rupture of a C-CH3 bond, which leads to the formation of methyl and CH2=C=CHCH2.The quantum yield for this process is 0.83 +/- 0.08 at 213.8 nm.The lifetime of the intermediate involved in this process is 20 ns at 184.9 nm.Similar quantities of ethylene and C3H4 (φ >/= 0.050) and propene and acetylene (φ >/= 0.023) are measured.All the measured yields decrease with an increase in the pressure.In addition to these fragmentation processes, isomerization reactions are also observed, particularly at 228.8 nm.They lead to the formation of 1,3- and 1,4-pentadiene as well as 3-methyl-1,2-butadiene.The Stern-Volmer plot for each isomer different and each plot shows a strong negative curvature, indicating the coplexity of the reaction process.The lifetime of each intermediate is 2 ns or less.
- Deslauriers, Helene,Dufour, Sylvain,Collin, Guy J.
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p. 1513 - 1519
(2007/10/02)
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- Gas-phase Kinetics of Pyrolysis of 1,2-Dimethylcyclopropene
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The pyrolysis of 1,2-dimethylcyclopropene has been studied in the temperature range 260-300 oC.The sole product is isoprene and material recovery was complete to within +/- 3.5percent.The reaction obeyed first-order kinetics and appeared to be homogeneous in a hexamethyldisilazane-conditioned Pyrex reactor, although surface catalysis could not be eliminated in a packed vessel.At 12 Torr (close to the high-pressure limit) rate constants fitted the Arrhenius equation (i).This study provides further evidence for the log(k/s-1) = (13.63 +/- 0.19) - (183.7 +/- 2.0kJmol-1)/RTln10 (i) deactivating effect of methyl substituents on cyclopropene isomerization.
- Hopf, Henning,Wachholz, Gerhard,Walsh, Robin
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p. 1103 - 1106
(2007/10/02)
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- Isomerisation des radicaux insatures. III. Radicaux α,α,β-, α,β,γ- et α,α,γ-trimethallyles
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α,α,β-, α,β,γ-, and α,α,γ-trimethallyl radicals have been generated in the 147.0-nm gas phase photolysis of 2,3,3-trimethyl-1-butene, 3,4-dimethyl-2-pentene, and 2,4-dimethyl-2-pentene, respectively.Under these conditions, the majority of allyl radicals have an internal energy sufficient for further decomposition: they give rise to the formation of various 1,3-dienes and small amounts of either 1,2- or 2,3-dienes.An internal sigmatropic 1,2-hydrogen atom transfer process is part of the proposed mechanism to explain such products.Moreover, the fragmentation of the trimethyl substituted allyl radicals involves the split of one β(C-C) bond, then one β(C-H), and, to a lesser extent, one central C-CH3 bond.
- Deslauriers, Helene,Collin, Guy J.
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p. 3168 - 3173
(2007/10/02)
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- SYNTHESIS OF ISOCOUMARINS VIA THALLATION-OLEFINATION OF BENZOIC ACIDS
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Benzoic acid and substituted benzoic acids are readily thallated by thallium(III) trifluoroacetate and subsequently reacted with palladium chloride and simple olefins, allylic halides, vinyl halides, or vinyl esters to give isocoumarins.The organic halide reactions are catalytic in palladium. 1,2- and 1,3-dienes also react catalytically to afford 4-alkylidene- and 3-vinyl-3,4-dihydroisocoumarins, respectively.Vinylcyclopropanes also afford 3-vinyl-3,4-dihydroisocoumarins.This highly convenient thallation-olefination approach appears quite general for the synthesis of isocoumarins.
- Larock, R. C.,Varaprath, S.,Lau, H. H.,Fellows, C. A.
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p. 5274 - 5284
(2007/10/02)
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- Cyclizations of ω-Allenyl Radicals
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Allenyl halides of structure (CH3)2C=C=CH(CH2)nX with n=3-6 have been prepared and reacted with n-Bu3SnH to generate the corresponding radicals for examination of the cyclization reactions of these reactive intermediates.The observed hydrocarbon products indicate that cyclization occurs for the n=3,4, and 5 radicals but not for the n=6 species.The n=3 radical isomerizes very efficiently by intramolecular addition to the sp carbon of the allene group.The n=5 intermediate reacts relatively slowly by attack at the near sp2 carbon.Both cyclization modes are observed for the n=4 species.The details of these radical cyclizations are discussed.
- Apparu, Marcel,Crandall, Jack K.
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p. 2125 - 2130
(2007/10/02)
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- Radical-Chain Addition of Benzenethiol to Allenes. Analysis of Steric Effects and Reversibility
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The radical-chain addition of benzenethiol to the monoalkylallenes 1a-e and the 1,1-dialkylallenes 6 and 8 has been studied.Attack by the benzenethiyl radical occurs at C2 and C3 of 1b-e in a ratio of 83:17.Increased attack (25percent) at C3 occurs with tert-butylallene (1a).The 1,1-dialkylallenes undergo attack only at C2.Deuterium-labeling studies indicate that the thiyl radical addition step is not detectably reversible under the reaction conditions.The internal alkene adducts 2, 3, 9 and 10 are the kinetically favored products.Rapid and reversible addition of the thiyl radical to the adducts results in complete stereochemical equilibration during the course of the reaction.The hydrogen atom abstraction step is reversible under the reaction conditions with 1a and 8 but not with 6 or the other monoalkylallenes.Treatment of the adducts derived from 1a and 8 with a catalytic quantity of iodine results in isomerization to the more thermodynamically stable adducts 4 and 11.The kinetics and thermodynamics of these reactions are discussed, and steric strain energies for the CH3...SC6H5 and t-Bu...SC6H5 interactions have been estimated to be 0.8-0.9 and 3.9-4.0 kcal/mol, respectively.
- Pasto, Daniel J.,Warren, Steven E.,Morrison, Marjorie A.
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p. 2837 - 2841
(2007/10/02)
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- Photolysis of Gaseous Tetramethylethylene between 185 and 230 nm
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The far-UV photolysis of gaseous tetramethyletylene was carried out at 184.9 (mercury line), 202,4-213.8 (zinc lines), and 214.4-228.8 nm (cadmium lines).The photoproducts may be divided int two groups.In the first one, the quantum yield of each product decreases with increase in the total pressure.The proposed mechanism involves the α(C-CH3) or the β(C-H) fragmentation of the photoexcited molecule.Excited (CH3)2CC(CH3)CH2* radicals decompose further at 184.9 nm, and 2,3-dimethyl-1,3-butadiene and 3-methyl-1,2-butadiene are the products.Excited (CH3)2C=CCH3* radicals decompose further, and 2-butyne and isoprene are the products.Isomers 2,3-dimethyl-1-butene, 1,1,2-trimethylcyclopropane, and 3,3-dimethyl-1-butene are products of the second group; its quantum yield increases with an increase in the total pressure.The results support a collisionally induced preisomerization mechanism.Finally, it seems that both groups of products are formed from a different set of excited states
- Collin, Guy J.,Deslauriers, Helene,Wieckowski, Andrzej
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p. 944 - 949
(2007/10/02)
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