Stoichiometric formation of conjugated dienyl ketones from 1,3-dienes and ketenes at a ruthenium(0) centre†
Abstract
A stoichiometric reaction of [Ru(η4-2,3-dimethyl-1,3-butadiene)(η4-1,5-COD)(NCMe)] (1a) with diphenylketene at room temperature produces a new zero-valent complex [Ru(η4-4,5-dimethyl-1,1-diphenylhexa-3,5-diene-2-one)(η4-1,5-COD)(NCMe)] (2aa) in 92% yield. This is the first example of conjugated dienyl ketone formation from 1,3-dienes and ketene. Similarly, the treatment of 1a with ethylphenylketene produces the decarbonylated coupling product (Z)-5-alkyl-2,3-dimethyl-5-phenylhepta-1,4-diene (5) in 77% yields.