Improved scope and diastereoselectivity of C–H activation in an expanded supramolecular host

<p>Chiral Ga<sub>4</sub>L<sub>6</sub> assembly Ga<sub>4</sub>(L<sup>N</sup>)<sub>6</sub> encapsulates cationic iridium half-sandwich complexes that activate aldehyde C–H bonds to form chiral, strongly bound piano-stool complexes. Herein, we report the expanded scope of the larger Ga<sub>4</sub>(L<sup>P</sup>)<sub>6</sub> host in mediating this transformation. The larger assembly significantly improves both the scope and the diastereoselectivity of this organometallic transformation generally, while substrate-specific interactions demonstrate that host size is an important, but not definitive, factor in determining diastereoselectivity.</p>