Readily Accessible and Easily Modifiable Ru-Based
Catalysts for Efficient and Z‑Selective Ring-Opening
Metathesis Polymerization and Ring-Opening/Cross-Metathesis
posted on 2016-02-19, 03:26authored byR. Kashif
M. Khan, Sebastian Torker, Amir H. Hoveyda
Rationally
designed Ru-based catalysts for efficient Z-selective
olefin metathesis are featured. The new complexes contain
a dithiolate ligand and can be accessed in a single step from commercially
available precursors in 68–82% yield. High efficiency and exceptional Z selectivity (93:7 to >98:2 Z:E) were achieved in ring-opening metathesis polymerization
(ROMP) and ring-opening/cross-metathesis (ROCM) processes; the transformations
typically proceed at 22 °C and are operationally simple to perform.
Complete conversion was observed with catalyst loadings as low as
0.002 mol %, and turnover numbers of up to 43 000 were achieved
without rigorous substrate purification or deoxygenation protocols.
X-ray data and density functional theory computations provide support
for key design features and shed light on mechanistic attributes.