Cyclization by Intramolecular Carbolithiation of Alkyl- and Vinyllithiums Prepared by Reductive Lithiation: Surprising Stereochemistry in the Lithium Oxyanion Accelerated Cyclization
作者:Kai Deng、Ahlem Bensari、Theodore Cohen
DOI:10.1021/ja027988c
日期:2002.10.1
yield cyclopentylmethyllithiums by unconjugated organolithiums is greatly increased (1) by generating the organolithiums by reductive lithiation of phenyl thioethers with aromatic radical anions and (2) by using allylic or homoallylic alcohol groups on the receiving alkene. This type of reductive lithiation allows virtually any kind of organolithium to be generated, usually in a connective manner.
Cyclization by Intramolecular Carbolithiation of Alkyl- and Vinyllithiums Prepared by the Action of Aromatic Radical Anions on Phenyl Thioethers. High Stereoselectivity in the Cyclization Accelerated by an Allylic Lithium Oxyanion<sup>1</sup>
The reductivelithiation of alkyl and vinyl phenyl thioethers by aromaticradicalanions is shown to be the most general method yet known for preparing organolithiums capable of intramolecular carbometalation of unactivated alkenes to produce five-membered rings and in one case a four-membered ring (in a far higher yield than known cases). The relative rates of cyclization for alkyllithiums are secondary
A general preparative method for carbonyl-protected γ-lithioketones via reductive lithiation. Synthetic uses of the bishomoenolate equivalents
作者:Theodore Cohen、Birong Zhang、John P. Cherkauskas
DOI:10.1016/s0040-4020(01)85652-0
日期:1994.1
react with aldehydes to yield alcohols. The vinyllithiums react with N,N-dimethylformamide to produce an enal containing a protected ketone group. The mixed cuprates, formed upon treatment of the organolithiums with cuprous bromide - dimethyl sulfide complex, undergo allylation with allyl bromide, conjugateaddition to enals and enones in the presence of trimethylsilylchloride to produce monoprotected