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Metalated nitriles: SNi' cyclizations with a propargylic electrophile.

ABSTRACT: A rare 5-exo-dig SNi' cyclization with magnesiated and lithiated nitriles affords a cis-fused hydrindane bearing an exocyclic allene. The cyclization of the dilithiated nitrile pits a stereoelectronic preference for a trans-hydrindane against a cyclization through a less strained transition structure to the corresponding cis-hydrindane. Computational modeling suggests that the dilithiated nitrile cyclizes to a cis-hydrindane because the preferred transition structure positions the lithium cation in a cone of electron density that bridges the nitrile-bearing carbon, an alkoxide, and an electron-rich alkyne functionality.

SUBMITTER: Lu P

PROVIDER: S-EPMC4480775 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Metalated nitriles: SNi' cyclizations with a propargylic electrophile.

Lu Ping P Pakkala Venkata S VS Evanseck Jeffrey D JD Fleming Fraser F FF

Tetrahedron letters 20150601 23

A rare 5-exo-dig SNi' cyclization with magnesiated and lithiated nitriles affords a cis-fused hydrindane bearing an exocyclic allene. The cyclization of the dilithiated nitrile pits a stereoelectronic preference for a trans-hydrindane against a cyclization through a less strained transition structure to the corresponding cis-hydrindane. Computational modeling suggests that the dilithiated nitrile cyclizes to a cis-hydrindane because the preferred transition ...[more]

PMID: 26120212

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