Synthesis and reactivity of oxygen chelated ruthenium carbene metathesis catalysts

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• 作者：Yiran Zhang^a ; Mingbo Shao^b ; Huizhu Zhang^a ; Yuqing Li^a ; Dongyu Liu^a ; Yu Cheng^a ; Guiyan Liu^a ; ^{guiyanliu2013@163.com" class="auth_mail} ; Jianhui Wang^b ; ^{wjh@tju.edu.cn" class="auth_mail}
• 关键词：Olefin metathesis ; Ruthenium ; N-Heterocyclic carbenes ; Homogeneous catalysis
• 刊名：Journal of Organometallic Chemistry
• 出版年：15 April, 2014
• 年：2014
• 卷：756
• 期：Complete
• 页码：1-9
• 全文大小：1544 K

文摘

The rate of initiation of Hoveyda catalysts is affected by the electronic and steric effects that act upon the Ru鈰疧 coordination. In order to boost the activity of Hoveyda catalysts, a series of new oxygen chelated ruthenium carbene metathesis catalysts containing an N-heterocyclic carbene (NHC) and a carbonyl group has been developed, and their catalytic activities for olefin metathesis reactions were investigated. The aliphatic end groups of complexes (H₂IMes)(Cl)₂RuC(H)[(C₆H₃X)OCH(Me)(C(O)OEt)(X聽=聽H, OMe, Me, NO₂)] were functionalized by the attachment of a straight-chain ester. The X-ray structures of complex聽(H₂IMes)(Cl)₂RuC(H)[(C₆H₄)OCH(Me)(C(O)NMe₂)] showed that the carbonyl oxygen of the amide and the terminal oxygen of the benzylidene ether are both coordinated to the metal to give an octahedral structure. However, the carbonyl oxygen of complexes (H₂IMes)(Cl)₂RuC(H)[(C₆H₃X)OCH(CH₂C(O)OCH₂)(X聽=聽H, OMe)] does not coordinate to the metal due to the steric effect of the lactone. All these complexes were used as catalysts for olefin metathesis reactions and all exhibited excellent performances for the ring-closing metathesis (RCM) of diethyl diallymalonate at 30聽掳C. The initiation rate of these catalysts was higher than that for the Hoveyda catalyst ((H₂IMes)(Cl)₂RuC(H)(C₆H₄-2-OⁱPr)) and these complexes are also active for cross metathesis (CM).