Abstract
The quest for general and highly efficient and enantioselective catalytic route to
chiral alcohols remains a formidable challenge in asymmetric synthesis. Here, we highlight
our recent work of asymmetric transfer hydrogenation (ATH) of N-methyliminodiacetyl (MIDA) acylboronates, showcasing a versatile platform for the
efficient synthesis of enantiomerically enriched secondary alcohols. Acyl-MIDA-boronates
harboring diverse (het)aryl, alkyl, alkynyl, alkenyl, and carbonyl substituents can
be hydrogenated, yielding various α-borylated alcohols with high ee values. Crucially,
the boron moiety can be easily transformed into other groups, allowing access to previously
unattainable carbinols adorned with two structurally similar substituents. The enantioselectivity-directing
role of BMIDA is elucidated by computational analyses, which stems from the CH–O electrostatic
attraction between the η6-arene-CH of the catalyst and the σ-bonded oxygen atoms within BMIDA. This work represents
the first asymmetric transformation on acylboronates and expands the domain of asymmetric
transfer hydrogenation.
Key words
asymmetric transfer hydrogenation - BMIDA - acylboronate - dicarbonyl boronate - α-boryl
alcohol