Multiple
Absolute Stereocontrol in Cascade Lactone
Formation via Dynamic Kinetic Resolution Driven by the Asymmetric
Transfer Hydrogenation of Keto Acids with Oxo-Tethered Ruthenium Catalysts
A straightforward
asymmetric construction of chiral fused γ-
and δ-lactones containing multiple contiguous stereocenters
was successfully developed by either (1) the dynamic kinetic resolution–asymmetric
transfer hydrogenation (DKR-ATH) reaction using oxo-tethered Ru(II)
complexes followed by syn-selective lactonization
or (2) the tandem DKR-ATH/lactonization in combination with asymmetric
hydrogenation catalyzed by Ru–chiral diphosphine complexes.
The expedient protocol is applicable to the enantioselective synthesis
of natural wine lactone and a biologically active benzo-fused lactone
with an unprecedented level of diastereo- and enantioselectivity.