Chiral ruthenium complex/Ph2P(2-furyl)-catalyzed asymmetric nucleophilic addition of aryl aldehyde hydrazones to simple ketones.

An efficient synthesis of chiral tertiary alcohols through asymmetric nucleophilic addition reaction of aldehyde hydrazones to simple ketones (especially aryl/methyl ketones) has been well established. Aryl aldehydes could be used as latent benzyl carbanion equivalents via reductive polarity reversal. The key to the success of the asymmetric reaction was the combination of an achiral monophosphine ligand Ph2P(2-furyl) with a chiral diamine derivative, which enhanced the enantioselectivity and reactivity. Density functional theory calculations revealed the hydrogen bond interactions between the chiral diamine derivative, the achiral monophosphine ligand, and the base anion, which combined to induce the desired enantioselectivity. Moreover, further synthetic transformation of tertiary alcohols with high chirality transfer was also demonstrated.