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Selective Boryl‐Anion Migration in a Vinyl sp 2 −sp 3 Diborane Induced by Soft Borane Lewis Acids
Author(s) -
Fasano Valerio,
Cid Jessica,
Procter Richard J.,
Ross Emily,
Ingleson Michael J.
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201808216
Subject(s) - borane , chemistry , intramolecular force , steric effects , medicinal chemistry , diborane , reagent , boranes , boron , electrophile , stereochemistry , organic chemistry , catalysis
An intramolecular 1,2‐boryl‐anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B 2 Pin 2 )] − using “soft” BR 3 electrophiles (BR 3 =BPh 3 or 9‐aryl‐BBN). The soft character is key to ensure 1,2‐migration proceeds instead of oxygen coordination/B−O activation. The BR 3 ‐induced 1,2‐boryl‐anion migration represents a triple borylation of a vinyl Grignard reagent using only B 2 Pin 2 and BR 3 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 B 2 Pin 2 , 1,2‐boryl‐anion migration can be suppressed in favor of intermolecular {BPin} − transfer to BPh 3 , thus enabling simple access to unsymmetrical sp 2 −sp 3 diboranes.