Chiral-Anion-Dependent
Inversion of Diastereo- and
Enantioselectivity in Carbonyl Crotylation via Ruthenium-Catalyzed
Butadiene Hydrohydroxyalkylation
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Abstract
The ruthenium catalyst generated in situ from H<sub>2</sub>Ru(CO)(PPh<sub>3</sub>)<sub>3</sub>, (<i>S</i>)-SEGPHOS,
and a TADDOL-derived
phosphoric acid promotes butadiene hydrohydroxyalkylation to form
enantiomerically enriched products. Notably, the observed diastereo-
and enantioselectivity is the opposite of that observed using BINOL-derived
phosphate counterions in combination with (<i>S</i>)-SEGPHOS,
the same enantiomer of the chiral ligand. Match/mismatch effects between
the chiral ligand and the chiral TADDOL-phosphate counterion are described.
For the first time, single-crystal X-ray diffraction data for a ruthenium
complex modified by a chiral phosphate counterion are reported