Scope and selectivity of B(C6F5)3-catalyzed reactions of the disilane (Ph2SiH)2

• New functionalized disilanes result from borane-catalyzed Si-H activation chemistry.
• Substrate bulk and its tendency to bind the catalyst affect selectivity and activity.
• Strategies emerge for the preparation of unsymmetrically substituted disilanes.

The diverse catalytic activity of the electrophilic borane B(C6F5)3 in reactions of silanes with organic substrates has been exploited extensively in studies that mostly focus on very particular, useful functional group transformations in organic synthesis. This study examines the potential for harnessing the collective, broad scope of these transformations in the preparation of new oligosilane derivatives. Borane-catalyzed hydrosilation, heterodehydrogenative coupling, and dealkylative coupling reactions of a wide range of substrates with the disilane (Ph2SiH)2 were investigated. These allowed new mono- and disubstituted disilanes to be prepared that contain SiO, SiS, and SiC linkages. Challenges and opportunities are described that arise from competing “over-reduction” chemistry, and the sensitivity of the catalysis to both the Lewis basicity and steric bulk of the substrates is examined.

Borane-catalyzed SiH activation reactions can allow the selective functionalization of a simple disilane, but obtaining the disubstituted product can be challenging for bulky substrates. This opens the door for mixing and matching bulky and small functional groups in the synthesis of new, unsymmetrically disubstituted disilanes.Figure optionsDownload as PowerPoint slide