Transforming Racemic Compounds into Two New Enantioenriched Chiral Products via Intermediate Kinetic Resolution

Converting
racemic compounds to enantioenriched products
is an
important and economic approach for accessing enantioenriched chiral
molecules. A common method is kinetic resolution. Herein, we present
a mode of kinetic resolution that transforms racemic compounds into
enantioenriched products, in which the kinetic resolution of reaction
intermediates is the key. Catalyzed by a single Ru complex, racemic
allylic alcohols are shown to react with a glycine-derived Schiff
base to afford two chiral compounds, a δ-carbonyl product and
a δ-hydroxy variant, with good yields and stereoselectivities
(up to >20:1 dr, 99% ee, 920 s factor). Mechanistic studies suggest
that multiple hydrogen transfer events exist in the reaction: a dehydrogenative
coupling process, which leads to a pair of racemic intermediates,
and a transfer hydrogenation-enabled kinetic resolution process that
resolves the intermediates, alongside H2 release at the
catalyst.