Synthesis And Property Study Of New Ruthenium Olefin Metathesis Complexes

Olefin metathesis is a unique carbon skeleton rearrangement in which unsaturated carbon-carbon bonds are rearranged in the presence of metal carbene complexes. Recently, Ru-based olefin metathesis catalysts are widely used in organic synthesis. However, these currently available ruthenium carbene complexes face some problems, such as low TON （turn over number）, poor heat resistance and catalytic selectivity. In order to solve these problems, a series of new ruthenium olefin metathesis catalysts with high activity and selectivity were designed and synthesized.In this paper, the following aspects have been included.1. A series of ruthenium carbene catalysts containing carbonyl groups were developed, and their catalytic activities were carefully investigated for the olefin metathesis reactions. Catalytic study showed that the catalytic activity of these ruthenium carbene catalysts containing carbonyl groups was significantly increased, giving important evidence for the designation of high performance catalysts for olefin metathesis in the future.2. A two-core ruthenium carbene complex {[RuCl（=CHPCy₃）（PCy₃）]₂ （μ-Cl）₃}⁺·[BF₄]^- was designed and synthesized. Further study shows that this two-core ruthenium complex is a selective catalyst for RCM （ring-closing metathesis） of unsubstituted terminal dienes. More importantly, no isomerized byproduct was observed for N- and O-substrates when the two-core ruthenium complex was used as catalyst at elevated temperature （137℃）, indicating that the complex is a chemo-selective catalyst for RCM reactions.3. A cationic ruthenium carbyne complex [（H₂IMes）RuCl₂（≡CPh）（PCy₃）]⁺·[I₅]^- was prepared and was found to be able to initiate the RCM reactions with moderate to good activities. More importantly, no isomerized byproduct was observed for N- and O-substrates when the ruthenium carbyne complex was used as catalyst at elevated temperature （137℃）, which lights a new insight on designation of high temperature sustained catalyst for RCM reactions.4. Using the olefin metathesis catalyst RuCl₂（=CHPh）（PCy₃）₂, a tandem RCM-Hydrogenation raction was achieved in which dienes substrates were converted into saturated carbon ring compounds, representing an important carbon-carbon transport method.