- Allylation with Pummerer-generated Subtituted Vinylthionium Ions
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Pummerer-derived substituted vinylthionium ions (allyl phenyl sulfoxide, TMSOTf, EtN(i-Pr)2, CH2Cl2, -78 deg C) with a β-trimethylsilylmethyl (2), γ-phenyl (14), or γ-phenylthio (15) group allylate the enol silyl ethers of acetophenone (3) and cyclohexanone (4) in good yield.Allylation with (14) and (15) required slow addition of base in order to limit the rate of production of intermediate, and thus avoid unwanted sila-Pummerer type products.Huenigs's base conjugate addition was not observed in these cases.Both the (E)- and (Z)- forms of allyl sulfoxide (15) were shown to equilibrate to the (E)-transoid conformer prior to allylation resulting in exclusive (E)-vinyl sulfide formation.Blocking of the γ-position resulted in preferential α-attack.
- Hunter, Roger,Michael, Joseph P.,Simon, Clive D.,Walter, Daryl S.
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p. 9365 - 9376
(2007/10/02)
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- Selenium-Stabilized Carbanions. Synthesis of Enals and Silyl Enones Using 1,3-Bis(phenylseleno)propene
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The utility of 1,3-bis(phenylseleno)propene (4) as a propenone synthon having n3 (1) or n1 and n3 (3) reactivity has been examined.Deprotonation of 4 with lithium diisopropylamine in THF at -78 deg C proceeds to give a lit
- Reich, Hans J.,Clark, Mark C.,Willis, W.W.
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p. 1618 - 1623
(2007/10/02)
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