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

Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ruthenium carbene complexes of the Grubbs second generation-type RuCl(H(2)IMes)(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 degrees C. The hemilabile 4-methoxy-substituted pyridinyl alcoholato ligand improved the catalyst stability, activity and selectivity for 1-octene metathesis significantly at 110 degrees C.