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Selective Boryl-Anion Migration in a Vinyl sp2 -sp3 Diborane Induced by Soft Borane Lewis Acids.

ABSTRACT: An intramolecular 1,2-boryl-anion migration from boron to carbon has been achieved by selective activation of the ??system in [(vinyl)B2 Pin2 )]- using "soft" BR3 electrophiles (BR3 =BPh3 or 9-aryl-BBN). The soft character is key to ensure 1,2-migration proceeds instead of oxygen coordination/B-O activation. The BR3 -induced 1,2-boryl-anion migration represents a triple borylation of a vinyl Grignard reagent using only B2 Pin2 and BR3 and forms differentially protected 1,1,2-triborylated alkanes. Notably, by increasing the steric bulk at the ??position of the vinyl Grignard reagent used to activate B2 Pin2 , 1,2-boryl-anion migration can be suppressed in favor of intermolecular {BPin}- transfer to BPh3 , thus enabling simple access to unsymmetrical sp2 -sp3 diboranes.

SUBMITTER: Fasano V

PROVIDER: S-EPMC6221116 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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