Non-biaryl Atropisomerism at the C-B Bond in Sterically Hindered Aminoarylboranes

Sterically hindered aminoarylboranes featuring atropisomerism about the C-B bond were prepared by addition of organomagnesium species onto readily accessible dialkylamine-borane complexes. Some of these aminoarylboranes, isosteres of vinyl styrene derivatives, were resolved by HPLC on the chiral stationary phase. They are the first examples of a non-biaryl type system which display slow rotation about a C-B bond.