Catalytic Asymmetric Carbene Insertion Reactions into B−H Bonds Using a Ru(II)‐Pheox Complex

The Ru(II)‐Pheox catalyzed B−H bond insertion reactions of α‐methyl diazoesters with phosphine‐ and amine‐borane adducts were successfully developed. A unique α‐methyl diazoester (dinaphthylenyl diazopropionate) with triphenylphosphine‐borane afforded the highest enantioselectivity (up to 98 % ee ). Moreover, a unique dinaphthylenyl diazophenylacetate was newly synthesized, leading to improved yield and enantioselectivity of the carbene transfer B−H insertion reaction.