- Synthesis and reactivity of functional 1-methyl-silacyclopentenes
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The silylenes MeSiCl, MeSiOMe and MeSiNMe2 can be thermally generated from disilanes and trapped by butadiene, isoprene and 2,3-dimethylbutadiene to give functionally-substituted silacyclopentenes.Some examples of cycloadditions to heterodienes are includ
- Heinicke, J.,Gehrhus, B.,Meinel, S.
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- Synthesis of unsaturated silyl heterocycles via an intramolecular silyl-heck reaction
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We report the synthesis of unsaturated silacycles via an intramolecular silyl-Heck reaction. Using palladium catalysis, silicon electrophiles tethered to alkenes cyclize to form five- and six-membered silicon heterocycles. The effects of alkene substitution and tether length on the efficiency and regioselectivity of the cyclizations are described. Finally, through the use of an intramolecular tether, the first examples of disubstituted alkenes in silyl-Heck reactions are reported.
- Reid, William B.,McAtee, Jesse R.,Watson, Donald A.
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p. 3796 - 3803
(2019/10/11)
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- Enantioselective Synthesis of Silacyclopentanes
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A variety of functionalized silacyclopentanes were synthesized by highly enantioselective β-eliminations of silacyclopentene oxides followed by stereospecific transformations. The reaction mechanism of the β-elimination was elucidated by DFT calculations. An in vitro biological assay with an oxy-functionalized silacyclopentane showed substantial binding to a serotonin receptor protein.
- Igawa, Kazunobu,Yoshihiro, Daisuke,Abe, Yusuke,Tomooka, Katsuhiko
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p. 5814 - 5818
(2016/05/09)
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- 1: 2-Adducts from Silylenes and 1,3-butadiene
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Photochemical generation of dimethylsilylene, methyl(phenyl)silylene and diphenylsilylene in the presence of high concentrations of 1,3-butadiene leads to the formation of 1-sila-3,4-divinylcyclopentanes as major products in addition to the anticipated 1-silacyclopent-3- enes.Also obtained are the ene-reaction products from the silenes, formed by formal 1,3-silyl shifts in the bis(trimethylsilyl)arylsilanes that are employed as the photochemical precursors of MePhSi: and Ph2Si:.Evidence is presented that both the divinylsilacyclopentanes and the silacyclopent-3-enes arise from vinylsilirane intermediates that can be trapped by acetone, yielding stable 3,3-dimethyl-4-vinyl-1- sila-2-oxolanes.Keywords: Silicon; Silylene
- Bobbitt, Kevin L.,Gaspar, Peter P.
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- DIORGANOSILACYCLOPENT-3-ENE DERIVATIVES FROM DIORGANODICHLOROSILANES AND BUTADIENEMAGNESIUM: EVIDENCE FOR CROTYL-GRIGNARD INTERMEDIATES
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Reactions of substituted dichlorosilanes, R1R2SiCl2 (R1=CH3, R2=Ph, vinyl), with butadienemagnesium yield methoxybutenylsilane derivatives and silacyclopent-3-enes after treatment with methanol at -70 deg C.For R=vinyl, a substituted cyclodeca-3,8-diene is formed in addition to the 1,4-disilylated butenylic species.The nature of the range of products suggests that silyl-substituted crotyl-Grignard compounds are the major intermediates.
- Richter, Wolf Juergen
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- PHOTOLYSIS OF ORGANOPOLYSILANES. THE REACTION OF PHOTOCHEMICALLY GENERATED METHYLPHENYLSILYLENE WITH CONJUGATED DIENES
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Photolysis of 2-phenylheptamethyltrisilane (I) in the presence of acyclic and cyclic conjugated dienes has been investigated using both a high-pressure mercury lamp with a quartz filter and a low-pressure mercury lamp with a Vycor filter.Irradiation of I in the presence of 1,3-butadiene, isoprene or 2,3-dimethylbutadiene with a high-pressure mercury lamp gave a product arising from photochemical isomerization of a silacyclopropane derivative and a compound apparently formed by 1,4-silylene addition, along with a 1/1 "ene" adduct of the diene to a photo-rearranged intermediate containing the silicon-carbon double bond.Irradiation of I in the presence of the conjugated diene with a low-pressure mercury lamp, followed by treatment of the product with methanol, afforded a methoxysilane arising from methanolysis of the corresponding silacyclopropane, together with the isomerization product, silacyclopentene and rearranged addition product.Irradiation of I in the presence of cyclopentadiene with a high-pressure mercury lamp produced methylphenylsilylcyclopentadiene, while irradiation of a similar mixture with a low-pressure mercury lamp followed by treatment with methanol gave 4-(methoxymethylphenylsilyl)-1-cyclopentene.With 1,3-cyclooctadiene, the photochemically generated methylphenylsilylene afforded many types of addition product.Photolysis of I in the presence of 1,3-cyclohexadiene, however, afforded none of the silylene addition products.
- Ishikawa, Mitsuo,Nakagawa, Ken-Ichi,Enokida, Ryuichi,Kumada, Makoto
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p. 151 - 163
(2007/10/02)
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