1 research outputs found
Rational and Then Serendipitous Formation of Aza Analogues of Hoveyda-Type Catalysts Containing a Chelating Ester Group Leading to a Polymerization Catalyst Family
Analogues
of the well-known Hoveyda–Grubbs catalyst bearing
both a chelating ester function and a chelating nitrogen atom were
obtained. These complexes behave differently depending on the character
of the chelating amine. Complexes containing a secondary amine underwent
unexpected spontaneous oxidation of the amine group, leading to the
Schiff base analogues. In contrast, complexes containing a tertiary
amine were prone to intramolecular cyclization in the presence of
a base (Et<sub>3</sub>N). Probing the activity of such (pre)catalysts
in ring-closing metathesis reactions (RCMs) revealed their dormant
character and excellent thermo-switchability. In particular, complexes
bearing an iminium nitrogen fragment were found to be very useful
in a delayed ring-opening metathesis polymerization (ROMP) and were
therefore commercialized