In alkene isomerization

OH must help subsequent isomerization, because ( )-30 is stable in the presence of 1, even after 2 d at 70°C. To test whether the bulk of the silyl ether protecting group was responsible for this reactivity difference, compound 32 was allowed to isomerize, forming a high yield of (ii)-33 at room temperature. In this case, heating at 70°C for 15 h does seem to lead to traces of what is tentatively identified as 34, but the second isomerization is clearly much slower than the first. Further studies are planned to elucidate the role of a hydroxyl substituent in alkene isomerization... 

The superbasic catalysts show very high activity in alkene isomerization reactions. The isomerization of 1-pentene and 1-hexene and trans 2-pentene has been examined in the presence of MgO and MgO on to which metallic sodium has been evaporated. 

A second general point about hydrogenation is that the final step, the reductive elimination of the product, is irreversible. This contrasts with the situation in alkene isomerization. In a reversible cycle, the products can equilibrate among themselves and a thermodynamic mixture is always obtained if we wait long enough and if the catalyst retains its activity. This is not the case in hydrogenation, if it were, the R- and S-products would eventually come to equilibrium and the ee would go to zero with time in an asymmetric hydrogenation. Only an... 

The jj -allyl mechanism probably operates also in alkene isomerizations catalysed by bis(benzonitrile)dichloropalladium. 

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