- Synthesis of functionalized polycarbosilanes via one-pot ADMET polymerization-macromolecular substitution
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Three substituted unsaturated polycarbosilanes were prepared from the same parent using a two-step, one-pot ADMET polycondensation-nucleophilic substitution route. Condensation metathesis of di(4-pentenyl)dichlorosilane using Schrock's [Mo] catalyst produces a polymer backbone containing two reactive silicon-chlorine bonds per unit. Replacement of these bonds with stable alkyl moieties was performed using an excess of alkyllithium reagent without undesirable main chain alkylation or cross-linking. Upon functionalization, moisture-stable polymers were synthesized, indicating quantitative substitution was achieved. All of the resulting polymers are amorphous, elastomeric materials. Variation of the two pendant groups from phenyl to methyl resulted in a Tg change of over 85°C.
- Church, A. Cameron,Pawlow, James H.,Wagener
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- The preparation of HfC/C ceramics via molecular design
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Polymer derived ceramics have received lots of attention throughout the last few decades. Unfortunately, only a few precursor systems have been developed, focusing on silicon based polymers and ceramics, respectively. Herein, the synthesis of novel hafniu
- Inzenhofer, Kathrin,Schmalz, Thomas,Wrackmeyer, Bernd,Motz, Guenter
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- PIKFYVE KINASE INHIBITORS
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The present invention relates to compounds useful as inhibitors of phosphatidylinositol-3-phosphate 5-kinase (PIKfyve) as well as their use for treating diseases and disorders associated with PIKfyve.
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Page/Page column 263-264
(2021/08/20)
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- Synthesis of 1-azaspiro[4.4]nonan-1-oxyls via intramolecular 1,3-dipolar cycloaddition
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Sterically shielded nitroxides of the pyrrolidine series have shown the highest resistance to reduction. Here we report the synthesis of new pyrrolidine nitroxides from 5,5-dialkyl-1-pyrroline N-oxides via the introduction of a pent-4-enyl group to the nitrone carbon followed by an intramolecular 1,3-dipolar cycloaddition reaction and isoxazolidine ring opening. The kinetics of reduction of the new nitroxides with ascorbate were studied and compared to those of previously published (1S,2R,3′S,4′S,5′S,2″R)-dispiro[(2-hydroxymethyl)cyclopentan-1,2′-(3′,4′-di-tert-butoxy)pyrrolidine-5′,1″-(2″-hydroxymethyl)cyclopentane]-1′-oxyl (1).
- Khoroshunova, Yulia V.,Morozov, Denis A.,Taratayko, Andrey I.,Gladkikh, Polina D.,Glazachev, Yuri I.,Kirilyuk, Igor A.
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supporting information
p. 2036 - 2042
(2019/09/30)
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- Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
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The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
- Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
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supporting information
p. 17305 - 17313
(2019/11/03)
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- A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins
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A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.
- Boukattaya, Fatma,Caillé, Julien,Ammar, Houcine,Rouzier, Florian,Boeda, Fabien,Pearson-Long, Morwenna S. M.,Bertus, Philippe
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p. 906 - 916
(2016/03/12)
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- MACROCYCLIC AND BICYCLIC INHIBITORS OF HEPATITIS C VIRUS
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Compounds of formula (I):or pharmaceutically acceptable salts thereof, wherein the various substituents are defined herein, methods of using said compounds, and pharmaceutical compositions containing said compounds.
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Page/Page column 94
(2014/09/29)
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- Synthesis of a platform to access bistramides and their analogues
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The platform C14-C40, which can be used to prepare bistramide C and 39-oxobistramide K, was synthesized in 19 steps with an overall yield of 6.2%. Furthermore, the chemoselective reduction of the ketone at C-39 was performed giving an easy access to bistramides A, B, D, K, and L. Finally, the versatility of the synthesis of the C14-C40 fragment can allow the preparation of a large variety of stereoisomers to produce bistramide analogues.
- Commandeur, Malgorzata,Commandeur, Claude,Cossy, Janine
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supporting information; scheme or table
p. 6018 - 6021
(2011/12/16)
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- l , l , 3-TRI0X0-l , 2 , 5-THIADIAZ0LIDINES AND THEIR USE AS PTP-ASES INHIBITORS
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Compounds of the formula are inhibitors of protein tyrosine phosphatases (PTPases) and, thus, may be employed for the treatment of conditions mediated by PTPase activity. The compounds of the present invention may also be employed as inhibitors of other e
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Page/Page column 71
(2010/11/27)
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- 6R-(3,6-DIDEOXY-L-ARABINO-HEXOPYRANOSYLOXY)HEPTANOIC ACID, PREPARATION PROCESS FOR THE SAME AND DAUER EFFECT THEREOF
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The present invention relates to a determination of a stereochemistry, a synthesis and dauer effect of 6R-(3,6-dideoxy-L-arabino-hexopyranosyloxy) heptanoic acid as a pheromone isolated from the Caenorhabditis elegance related to suppress of aging and
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Page/Page column 6; 13-14
(2008/06/13)
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- A concise synthesis of an advanced Clerodin intermediate through a Vaultier tandem reaction
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A highly functionalised precursor of the antifeedant natural product Clerodin has been synthesised with good diastereo-control. Key steps include a three-component version of the Vaultier tandem sequence, and an oxidative decarboxylation with a simple experimental procedure.
- Lallemand, Jean-Yves,Six, Yvan,Ricard, Louis
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p. 503 - 513
(2007/10/03)
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- Reagents and methods for the detection and quantification of testosterone in fluid samples
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A Position 1 immunogen having the following formula: STR1 wherein: (a) P represents an immunogenic carrier material (b) X represents a linking moiety wherein --X--P is attached to a testosterone derivative (c) n is from 1 to 10, inclusive (d) the degree of substitution of P by the testosterone derivative is from 1 to 100%, inclusive.
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- Chemoselective Carbonyl Reduction Mediated by Low-valent Titanium
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Utilizing the rate difference in alkoxy alkyl radical formation from aldehydes versus ketones with low-valent titanium, aldehydes are preferentially reduced with tributyltin hydride.The difference in reactivity allows aldehydes to be reduced in the presence of ketones without laborious protection-deprotection steps.
- Adams, Christopher M.,Schemenaur, John E.
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p. 2359 - 2364
(2007/10/02)
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- Rearrangement of the Grignard reagent from 1-methylcyclobutylmethyl bromide: origins of the methyl substituent effect
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1-Methyl substitution leads to a small decrease (ca. 0.45) in the rate of the ring cleavage rearrangement of cyclobutylmethylmagnesium bromide.Comparison with literature data for 3- and 5-membered rings indicates that the methyl substituent shifts the equilibrium in the direction of ring cleavage, mostly by stabilization of the double bond of the open isomer, and possibly partly by destabilization of the organometallic function of the cyclic isomer.The reaction rate is decreased in both directions, probably because of increased transition state steric repulsions.
- Hill, E. Alexander,Hallade, Marc W.
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p. 263 - 272
(2007/10/02)
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