- The β-effect of silicon in the orthogonal geometry
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The inductive contribution to the β-effect of silicon has been investigated through the preparation of 1-(trimethylsilyl)bicyclo[2.2.2]octan-2-ol (5-OH) and its sulfonate derivatives. The dihedral relationship in 5 between the trimethylsilyl group and the
- Lambert, Joseph B.,Liu, Xiaoyang
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p. 203 - 210
(2007/10/03)
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- Use of Protected β-Bromocyclopentenones and β-Bromocyclohexenones as β-Acylvinyl Anion Equivalents
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Ethylene glycol ketals of the 3-bromocyclohex-2-en-1-one as well as its 2-methyl, 2-n-propyl, and 5,5-dimethyl derivatives have been prepared, and their reactions with butyllithium were studied.The organolithium reagents derived from the above compounds react with a variety of electrophiles to afford after acid hydrolysis the corresponding 3-substituted cyclohexenones.Attempts to prepare the ethylene glycol ketal of 2-methyl-3-bromocyclopent-2-en-1-one gave a low yield of the bromoketal.However, dithioketals of 3-bromocyclopent-2-en-1-one and its 2-methyl derivativecould be prepared in good yield.The metalation chemistry of the dithioketals in both the five- and six-membered-ring series was examined.The functionalization chemistry of the resulting organolithium compounds afforded after dithioketal hydrolysis 3-functionalized cyclohex-2-en-1-ones and cyclopent-2-en-1-ones.Several limitations of the chemistry using allyl bromide and cyclohexenone as electrophiles are noted.
- Shih, Chuan,Swenton, John S.
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p. 2825 - 2832
(2007/10/02)
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- An Efficient and Simple β-Acylvinyl Anion Equivalent for Cyclohexenones
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Dilithio species available from treatment of Δ3,4-3-bromocyclohexenone ketals with two equivalents of n-butyllithium serve as one-pot equivalents of β-vinyl-carbanions of cyclohexenones.These former ketals are available in good yield from the corresponding β-bromocyclohexenone by direct ketalization under controlled conditions.
- Shih, Chuan,Swenton, John S.
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p. 4217 - 4220
(2007/10/02)
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