Cross‐Metathesis Reactions of Homoallyl Methyl Malonates with Sterically Hindered Allylic Esters

The methyl malonate esters of 3‐buten‐1‐ol and 2‐methyl‐3‐buten‐1‐ol can be coupled efficiently to different methallylic esters in the presence of the second‐generation Grubbs catalyst to yield trisubstituted olefins by the cross‐metathesis reaction. Product selectivity and yields depend on the relative amounts of reagents and to a minor extent on the methallylic ester functional group. Alkyl substituents at either the allylic or the geminal positions significantly affect the product yields and the E / Z stereoselectivity.