ABSTRACT
A remarkable intermolecular dehydrative coupling reaction with the formation of a C-C bond was found for the vinylidene complexâ 2 a, yielding the dinuclear bisvinylidene complexâ 4 a. Complexâ 2 a containing 1-hydroxyindan moiety was first formed from the reaction of o-propynyl benzaldehyde 1 a with [Ru]-Cl ([Ru]=Cp(PPh3 )2 Ru) by a cyclization process. For analogous aldehyde 1 b containing an additional 1,3-dioxolane group on the aryl ring, similar intermolecular coupling yields the dinuclear bisvinylidene complexâ 4 b. However, the fluoro group on the aryl ring in aldehyde 1 c inhibits the coupling reaction, giving only the vinylidene complexâ 2 c. For the reactions of [Ru]-Cl in MeOH with compoundsâ 1 f, 1 g and 1 h, each with a ketone functionality, cyclization gives vinylidene complexesâ 2 f, 2 g and 2 h, respectively. However, no similar intermolecular coupling was observed, instead, the intramolecular dehydration yields 8 f, 8 g and 8 h, respectively. In CDCl3 , catalytic cyclization is observed for the o-propynylphenyl ketone 1 h with [Ru]-Cl at 50 °C giving the isochromene products 14 h. Furthermore, treatment of the o-propynylaryl α,ß-unsaturated ketones 1 k-m and 1 n with [Ru]-Cl in MeOH affords the corresponding vinylidene complexesâ 10 k-m and 11 n each with 1-benzosuberone moiety in the presence of NH4 PF6 . These intramolecular cyclization products were formed by the addition of Cß onto the terminal carbon of the alkene moiety. All these reaction products were characterized by spectroscopic methods. In addition, structures of complexesâ 4 a, and 10 l were confirmed by single crystal X-ray diffraction analysis.