om5b00857_si_003.cif (13.76 kB)
Facile Arylation of Four-Coordinate Boron Halides by Borenium Cation Mediated Boro-desilylation and -destannylation
dataset
posted on 2015-12-28, 00:00 authored by Daniel
L. Crossley, Jessica Cid, Liam D. Curless, Michael L. Turner, Michael J. InglesonThe addition of AlCl3 to four-coordinate boranes of
the general formula (C–N-chelate)BCl2 results in
halide abstraction and formation of three-coordinate borenium cations
of the general formula [(C–N-chelate)BCl]+. The
latter react with both arylstannanes and arylsilanes by boro-destannylation
and -desilylation, respectively, to form arylated boranes. Catalytic
quantities of AlCl3 were sufficient to effect high-yielding
arylation of (C–N-chelate)BCl2. Boro-destannylation
is more rapid than boro-desilylation and leads to double arylation
at the boron center, whereas in reactions with arylsilanes either
single or double arylation occurs dependent on the nucleophilicity
of the arylsilane and on the electrophilicity of the borenium cation.
The electrophilicity of the borenium cation derived from 2-phenylpyridine
was greater than that of the benzothiadiazole analogues, enabling
the boro-desilyation of less nucleophilic silanes and the direct electrophilic
borylation of 2-methylthiophene.