- α-Lithioalkoxysilanes: Applications to alkene synthesis
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α-Lithioalkoxysilanes [RO(Me2)Si]CH(Li)(X), where R=Me or Et and X=H or SiMe3, react with carbonyl compounds in hydrocarbon solution to produce alkenes in moderate to high yield via Peterson-type reactions. For X=SiMe3, the corresponding vinylsilanes are isolated directly following work-up. The reaction is regiospecific and shows fair stereoselectivity. When the carbonyl substrates are cyclic ketones in six- or seven-membered rings, the products are exocyclic alkenes. For X=H, the initial product is a β-hydroxysilane, which is then efficiently converted to the corresponding terminal alkene by heating with sodium acetate in acetic acid. Both types of α-lithioalkoxysilane reagents are amenable to reaction with enolizable carbonyl compounds.
- Bates, Tim F.,Dandekar, Sushama A.,Longlet, Jon J.,Thomas, Ruthanne D.
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- Antimalarial analogs of artemisinin
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Polyoxoheterocyclic tetracycles related to the Chinese antimalarial natural product qinghaosu (artemisinin) are disclosed. These materials have a STR1 core structure with an oxygen (carbonyl or alkyl ether) at position 12 and in some cases one or two alkyl or aralkyl substituents at position 11. These materials have antimalarial properties.
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- Carbocycle Formation via Intramolecular Insertion of Alkynes into Titanium-Carbon Bonds
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Treatment of alkyl titanocene chloride complexes with the Lewis acids EtAlCl2 or Me2AlCl resulted in intramolecular insertion of a tethered alkyne into the Ti-C bond.Regioselective alkyne insertion produced exocyclic trisubstituted alkene products resulting from four-, five-, and six-membered ring formation.In the case of cyclohexane formation, the alkyne was found to insert with syn stereoselectivity.
- Harms, Arthur E.,Stille, John R.
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p. 6565 - 6568
(2007/10/02)
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- A New Alkyllithium Reagent for the Direct Conversion of Aldehydes and Ketones to Vinylsilanes
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lithium (1), which is readily formed in hydrocarbon solvent from silane 2 and tert-butyllithium, reacts with carbonyl compounds to yield the corresponding alkenylsilanes 3 via a Peterson-type reaction.
- Bates, Tim F.,Thomas, Ruthanne D.
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p. 1784 - 1785
(2007/10/02)
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- Highly Stereoselective Synthesis of Vinylsilanes from Carbonyl Compounds
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The in situ generated (chlorolithiomethyl)trimethylsilane reacts at -60 deg C to -45 deg C with different aldehydes or ketones 1 to afford, after lithation with lithium naphthalenide at -78 deg C to 20 deg C, vinylsilanes 5a-h in a stereoselective manner.
- Barluenga, Jose,Fernandez-Simon, Jose L.,Concellon, Jose M.,Yus, Miguel
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p. 234 - 236
(2007/10/02)
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- BIS(BROMOMAGNESIO)TRIMETHYLSILYLMETHANE
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The reaction of Me3SiCH(MgBr)2 with magnesium amalgam in diisopropyl ether furnished the di-Grignard reagent Me3SiCH(MgBr)2 in 70 percent yield.Derivatization with Me3SnCl gave Me3SiCH(SnMe3)2 (6,94percent).Witting type reaction occured readily with benzophenone (80percent), but the yield was low with cyclohexanone (13percent).
- Heisteeg, B. J. J. van de,Schat, G.,Tinga, M. A. G. M.,Akkerman, O. S.,Bickelhaupt, F.
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p. 6123 - 6124
(2007/10/02)
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- Pyrolysis of 1-(Trimethylsilyl)-1-alkanols. New Carbene Precursors of Silylcarbene and Phenylcarbene
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Pyrolysis of bis(trimethylsilyl)phenylmethanol gave (trimethylsilyl)phenylcarbene by the elimination of trimethylsilanol and the products were compared with those of (trimethylsilyl)phenyldiazomethane.Alkylsilylcarbenes obtained from the pyrolyses of 1,1-bis(trimethylsilyl)-1-alkanols afforded vinyltrimethylsilanes in high yields. (Trimethylsilyl)phenylmethanols were found to be excellent precursors of phenylcarbenes and their intramolecular reactions were also studied.
- Sekiguchi, Akira,Ando, Wataru
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p. 5286 - 5290
(2007/10/02)
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