An intramolecular 1,2-boryl-anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B2Pin2)]− 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 B2Pin2 and BR3 and forms differentially protected 1,1,2-triborylated alkanes. Notably, by increasing the steric bulk at the β position of the vinyl Grignard reagent used to activate B2Pin2, 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.

Selective Boryl-Anion Migration in a Vinyl sp2−sp3 Diborane Induced by Soft Borane Lewis Acids / V. Fasano, J. Cid, R.J. Procter, E. Ross, M.J. Ingleson. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - 57:40(2018 Oct 01), pp. 13293-13297. [10.1002/anie.201808216]

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

V. Fasano
Primo
;
2018

Abstract

An intramolecular 1,2-boryl-anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B2Pin2)]− 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 B2Pin2 and BR3 and forms differentially protected 1,1,2-triborylated alkanes. Notably, by increasing the steric bulk at the β position of the vinyl Grignard reagent used to activate B2Pin2, 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.
1,2-migration; boranes; borylation; Grignard reagents; Lewis acids
Settore CHIM/06 - Chimica Organica
1-ott-2018
13-ago-2018
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/952297
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