Hydrovinylation of Olefins Catalyzed by RuCl₂(MeCN)₂(cod)/organoaluminum System

Abstract

  Codimerization of ethylene with styrene takes place in the presence of the RuCl₂(MeCN)₂(cod)/MAO catalyst at room temperature to yield 3-phenyl-1-butene accompanied by formation of 1,3-diphenyl-1-butene as a by-product. The reaction with molar ratio of [styrene]/[Ru]/[Al] = 10000/1/300 resulted in 83% conversion of styrene and 93% selectivity of 3-phenyl-1-butene after 2 h. RuCl₂(MeCN)₂(cod)/Et₂AlCl also catalyzes the hydrovinylation of styrene, and the reaction produces 3-phenyl-1-butene and 1,3-diphenyl-1-butene in 71:29 ratio after 30 min. ¹H NMR spectroscopy of the reaction mixture for a longer period revealed that 1,3-diphenyl-1-butene, the byproduct, was converted to 3-phenyl-1-butene, probably via Ru-catalyzed metathesis reaction of 1,3-diphenyl-1-butene with ethylene. RuCl₂(MeCN)₂(cod)/MAO also promotes hydrovinylation of norbornene and 1-phenyl-1,3-butadiene to give exo-2-vinylnorbornane and (E)-5-phenyl-3-methyl-1,4-pentadiene, respectively.