Asymmetric Transfer Hydrogenation of Secondary Allylic Alcohols

Abstract

Abstract Racemic secondary allylic alcohols were transformed into optically active secondary alcohols by a combined Ru‐catalyzed isomerization/asymmetric transfer‐hydrogenation reaction. The catalyst was generated in situ in isopropyl alcohol from di‐μ‐chlorobis[( p ‐cymene)chlororuthenium(II)], the chiral ligand (1 S ,2 S )‐ N ‐( p ‐tolylsulfonyl)‐1,2‐diphenylethylenediamine, and K 2 CO 3 , and the products were afforded in yields up to 97 % with up to 93 % enantiomeric excess without the use of hydrogen gas. A Hammett study revealed that the reaction rate was enhanced with electron‐withdrawing aryl substituents. The reaction supports the recent work published by Adolfsson et al. as new methodology for the synthesis of chiral compounds from allylic alcohols.