- A Novel Synthesis of (E)-gem-Dimetalloalkenes Containing Boron and Silicon: An Easy Access to Alkyl Trimethylsilyl Ketones
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A simple, novel synthesis of (E)-gem-dimetalloalkenes containing boron and silicon based on (Z)-1-bromo-1-alkenyl-boronate esters is developed. 1-Bromo-(Z)-1-alkenylboronate esters readily available from literature procedures smoothly undergo a reaction with trimethylsilyllithium (easily generated from hexamethyldisilane with methyllithium in hexamethylphosphoramide) to provide the corresponding 'ate' complexes. These 'ate' complexes undergo intramolecular nucleophilic substitution reaction to provide the corresponding (E)-1-alkenylboronate esters containing trimethylsilyl moiety in good isolated yields (72-85%). The carbon skeletons present in these intermediates are confirmed by oxidation to the corresponding alkyl trimethylsilyl ketones with sodium acetate and hydrogen peroxide.
- Bhat, Narayan G.,Tamm, Amanda,Gorena, Amanda
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- Efficient Generation and Synthetic Applications of Alkyl-Substituted Siloxycarbenes: Suppression of Norrish-Type Fragmentations of Alkanoylsilanes by Triplet Energy Transfer
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Acylsilanes have been known to undergo isomerization to siloxycarbenes under photoirradiation and the thus generated carbenes can be utilized for various synthetic reactions. But this carbene formation is not necessarily efficient with some alkanoylsilanes because Norrish-type fragmentations compete, which limit the synthetic utility of alkanoylsilanes as carbene precursors. In this study, generation of siloxycarbenes from alkanoylsilanes by visible-light-induced energy transfer was examined by using an Ir complex, [Ir{dF(CF3)ppy}2(dtbpy)]PF6, and was successfully applied to the C?C coupling reactions with boronic esters or aldehydes. This methodology efficiently suppressed undesired Norrish-type reactions and broadened synthetic utility of alkanoylsilanes.
- Abe, Manabu,Hagiwara, Chihiro,Ishida, Kento,Kusama, Hiroyuki,Yamazaki, Hokuto
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supporting information
p. 1249 - 1253
(2020/02/04)
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- α-Substituted acylsilanes via a highly selective [1,4]-Wittig rearrangement of α-benzyloxyallylsilane
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α-Benzyloxyallylsilane undergoes efficient [1,4]-Wittig rearrangement to generate an enolate intermediate that can be trapped with various electrophiles, thereby providing a new synthetic approach to substituted acylsilanes. The Royal Society of Chemistry
- Onyeozili, Edith N.,Maleczka Jr., Robert E.
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p. 2466 - 2468
(2008/09/16)
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- Studies on the deprotonation and subsequent [1,4]-Wittig rearrangement of α-benzyloxyallylsilanes
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Upon exposure to s-BuLi, benzyloxyallylsilane undergoes an unusually rapid and efficient [1,4]-Wittig rearrangement. Herein we describe efforts aimed at trapping the intermediate α-carbanion with an electrophile prior to rearrangement. The results of thes
- Onyeozili, Edith N.,Maleczka Jr., Robert E.
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p. 6565 - 6568
(2007/10/03)
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- Rhodium-catalyzed acylation of vinylsilanes with acid anhydrides
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A catalytic acylation of vinylsilane with acid anhydride is accomplished by the use of [RhCl(CO)2]2, in which the transmetalation between vinylsilane and rhodium(I) carbonyl complex plays a key role. The application of this acylation reaction to (1-acyloxyvinyl)silanes provides synthetic methods for α-acyloxy enones, α-diketones, and their derivatives.
- Yamane, Motoki,Uera, Kazuyoshi,Narasaka, Koichi
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p. 477 - 486
(2007/10/03)
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- Evaluation of C-trialkylsilyl enol and thioenol ethers as intermediates in the synthesis of acylsilanes
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C-silyl enol ethers or thioenol ethers have been prepared by a Peterson reaction, as intermediates for acylsilane synthesis. Bis(trialkylsilyl)(methoxy) - or -(methylsulfanyl)methanes bearing identical or different trialkylsilyl groups were used as starting materials in order to assess the selectivity of the Peterson elimination step. A good selectivity was observed only with ethers bearing the TMS and TBDMS groups. However, there is no practical interest to use such reagents owing to the difficulty to obtain them in correct yields. Bis(trimethylsilyl)(methylsulfanyl)methane proved to be a good reagent for the preparation of C-silyl thioenol ethers, which are hydrolyzed under classical acid conditions to give acylsilanes in fair overall yields. This convenient procedure was extended to the synthesis of bis(acylsilanes). Graphical Abstract.
- Hammaecher, Catherine,Ouzzane, Imad,Portella, Charles,Bouillon, Jean-Philippe
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p. 657 - 663
(2007/10/03)
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- Methyllithium-promoted Wittig rearrangements of α-alkoxysilanes
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(matrix presented) The Wittig rearrangements of α-alkoxysilanes, promoted by the action of methyllithium were studied. Depending on both the substrate and reaction conditions employed, [2,3]-, [1,2]-, or [1,4]-Wittig rearrangements can be realized. These rearrangements were shown to be initiated by either Si/Li exchange or deprotonation a to the silane. Furthermore the sigmatropic shifts can often be followed by other synthetically useful in situ chemical events.
- Maleczka Jr., Robert E.,Geng, Feng
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p. 1115 - 1118
(2008/02/09)
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