ROM-RCM of cycloalkene-yne

ROM-RCM of cycloalkene-yne 119 having a substituent at the 3-position of the cycloalkene would give a polymer because ruthenium carbene complex XVlll generated in this reaction could react with the starting alkyne. If this reaction is carried out under ethylene gas, the cyclized compound 120 should be formed by the reaction of XVlll with ethylene [Eq. (6.88)]. On the basis of this idea, ROM-RCM-CM of cycloalkene-yne 119 was carried out under ethylene gas " ... 

If ROM-RCM of cycloalkene-yne 123, which has a substituent at the 2-position of cycloalkene, is carried out under ethylene gas, what compound is formed In this reaction, ruthenium carbene XIX would be formed via [2-1-2] cycloaddition of ruthenium methylidene carbene and alkyne as shown in Eq. (6.91). If XIX reacts with an olefin intramolecularly or ethylene, bicyclic compound 124 or triene 125... 

Scheme 23 Plan for ROM-RCM of cycloalkene-yne having a substituent at the 1 -position.

Under an atmosphere of ethylene, the ROM-RCM of cycloalken-ynes, when the cycloalkene bears the alkyne moiety at the olefinic Cl position, produce dimeric and/or bicyclic compounds [22] (Scheme 9). The expected bicyclic product with a cyclooctadiene ring is obtained with a low yield, whereas the dimeric macrocycle is the major compound. 

Ring-Opening Metathesis (ROM)-Ring-Closing Metathesis (RCM) of Cycloalkene-Yne... 

Blechert carried out ROM-RCM-CM of cycloalkene-yne 121 in the presence of alkene instead of ethylene to give 122 ... 

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