Synthesis and application of novel ruthenium catalysts for high temperature alkene metathesis

Abstract

Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ruthenium carbene complexes of the Grubbs second generation-type RuCl(H2IMes)(O^N)(=CHPh), where O^N = 1-(2′-pyridinyl)-1,1-diphenyl methanolato, 1-(2′-pyridinyl)-1-(2′-chlorophenyl),1-phenyl methanolato, 1-(2′-pyridinyl)-1-(4′-chlorophenyl),1-phenyl methanolato and 1-(2′-pyridinyl)-1-(2′-methoxyphenyl),1-phenyl methanolato, are synthesized in very good yields. At high temperatures, the precatalysts showed high stability, selectivity and activity in 1-octene metathesis compared to the Grubbs first and second generation precatalysts. The 2-/4-chloro- and 4-methoxy-substituted pyridinyl alcoholato ligand-containing ruthenium precatalysts showed high performance in the 1-octene metathesis reaction in the range 80–110 °C. The hemilabile 4-methoxy-substituted pyridinyl alcoholato ligand improved the catalyst stability, activity and selectivity for 1-octene metathesis significantly at 110 °C