Synthesis and application of 1-cycloalkyl-1-(2'-pyridinyl)-methanolato ligand containing ruthenium catalysts for high temperature 1-octene metathesis

Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ligand containing 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-cyclopentyl-1-(2'-pyridinyl)-methanolato, 1-cyclohexyl-1-(2 '-pyridinyl)-methanolato, and 1-cycloheptyl-1-(2'-pyridinyl)-methanolato] were synthesized with very good yield. The precatalysts were tested for their activity and selectivity (60-90 degrees C) and the stability of the precatalysts were compared in 1-octene metathesis reaction. The catalytic performances and stabilities of the precatalysts were also compared with Grubbs first and second generation precatalysts. The precatalysts showed very good selectivity and activity in the temperature range 60-80 degrees C, compared to the Grubbs first and second generation precatalysts, in 1-octene metathesis. The 1-cyclopentyl-1-(2'-pyridinyl)-methanolato and 1-(2'-pyridinyl)-1,1-diphenyl-methanolato ligand containing ruthenium precatalysts showed comparable catalyst activity on 1-octene metathesis reaction at 80 degrees C than the 1-cyclohexyl-, and 1-cycloheptyl-1-(2'-pyridinyl)-methanolato ligand containing precatalysts. The hemilabile 1-cycloalkyl-1-(2'-pyridinyl)-methanolato ligands improved the catalyst activity and selectivity for 1-octene metathesis significantly compared to the PCy3 ligand at 80 degrees C. The catalytic lifetime of the cyclopentyl pyridinyl alcoholato ligand containing precatalyst, however, was shorter than diphenyl, cyclohexyl and cycloheptyl pyridinyl alcoholato ligand containing ruthenium precatalyst.

Automated summary

Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ligand containing ruthenium carbene complexes of the Grubbs second generation-type were successfully synthesized. These precatalysts exhibited good selectivity and activity, especially at temperatures ranging from 60 to 80 degrees Celsius, in the 1-octene metathesis reaction.