Latent Olefin Metathesis Catalysts Featuring Chelating Alkylidenes

The synthesis of a series of ruthenium-based metathesis catalysts featuring imine donors chelated through
the alkylidene group is described. The relative placement of the imine carbon−nitrogen double bond
(exocyclic vs endocyclic) has a major impact on the initiation behavior. When used in metathesis
applications, catalysts with an endocyclic imine bond show latent behavior and a high degree of tunability.
The incorporation of additional donor atoms is an additional strategy for controlling initiation behavior.
These latent catalysts could be useful in high-temperature applications.