High enantioselectivity was achieved in the copper-catalyzed hydroboration of bicyclic alkenes. Using (R,R)-taniaphos as a chiral ligand and pinacolborane (pinBH) as the hydroborating reagent, we obtained (R)-hydroborated products with high enantioselectivities up to &gt;99% ee for diverse bicylic alkenes including oxa- and azabicyclic alkenes. On the other hand, the same chiral ligand–copper precusor afforded (S)-hydroborated products in the presence of bis(pinacolato)diboron (B<sub>2</sub>pin<sub>2</sub>) and MeOH as the borylating reagent. Thus, the enantioselectivity switch in the copper-catalyzed asymmetric boron addition of bicyclic alkenes was first observed using different borylating reagents with the same chiral copper–ligand combination.

Enantioselectivity switch in the copper(I)-catalyzed boron additions

250th National Meeting (2015)

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