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

The Journal of Organic Chemistry
Kai DengTheodore Cohen

Abstract

The reductive lithiation of alkyl and vinyl phenyl thioethers by aromatic radical anions 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 > tertiary > primary, and the yields are very high. In the secondary case, the stereoselectivity is extremely high, producing a cyclopentylmethyllithium with a trans-2-alkyl substituent. A remarkable finding is that for all of the organolithiums a lithium oxyanionic group in the proximal allylic position to the alkene greatly accelerates the cyclization and leads almost exclusively to a trans relationship between the CH(2)Li group and the OLi group, the opposite relationship from that observed in intramolecular carbolithiations by allyllithiums. A mechanistic rationale for this divergence is discussed. One of the two types of proximal homoallylic lithium oxyanions exerts an analogous effect. An intriguing limitation, even occurring with the highly reactive secondary organolithium and in the presence of an allylic oxyanionic gro...Continue Reading

References

Aug 30, 2003·Organic & Biomolecular Chemistry·Iain ColdhamRichard E Rathmell

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Citations

Nov 21, 2008·Chemical Society Reviews·Francisco Foubelo, Miguel Yus
Aug 30, 2008·Chemical Communications : Chem Comm·Anne-Marie L Hogan, Donal F O'Shea
May 24, 2018·Organic & Biomolecular Chemistry·Qian ChenYanping Huo
Jul 24, 2018·Science Advances·Guillaume PoviePhilippe Renaud
Aug 15, 2008·Organic Letters·Robert J Bahde, Scott D Rychnovsky
Jun 9, 2021·The Journal of Organic Chemistry·Stefano NejrottiCristina Prandi
Sep 10, 2020·The Journal of Organic Chemistry·Feng ZhuMaciej A Walczak
Nov 26, 2013·Organic Letters·Laurent DebienSamir Z Zard

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