Study on the reactivity of the alkene component in ruthenium-catalyzed [2+2] cycloadditions between an alkene and an alkyne. Part 1

[GRAPHICS] The ruthenium-catalyzed [2 + 2] cycloadditions of 7-substituted norbornadie nes with an alkyne have been investigated. The cycloadditions were found to be highly regio and stereoselective, giving only the anti-exo cycloadducts as the single regio and stereoisomers in good yields. The results on the r elative rate of different 7-substituted norbornadienes in the Ru catalyzed [2 + 2] cycloadditions with an alkyne indicated that the reactivity of the alkene component decreases dramatically as the alkene becomes more electron deficient.