Symmetric acyclic allylic esters

Enantioselective Allylic Substitution of Symmetric Acyclic Allylic Esters... 

Enantioselective allylic substitutions of cyclic allylic esters have been more challenging to develop than enantioselective reactions of symmetrical, acyclic allylic esters. In one set of reactions, racemic allylic esters react to form non-racemic products by addition of carbon or nitrogen nucleophiles in the presence of palladium catalysts. In these cases, attack at the two termini of the allylic intermediate generates the two enantiomers. Only a handful of ligands have generated catalysts that form products from the substitution of aliphatic. 

As described in the previous section, when acyclic and symmetric allylic esters such as l,3-diphenyl-2-propenyl acetate and l,3-dialkyl-2-propenyl esters are used as substrates, high to excellent enantioselective allylic alkylation is performed by using a variety of chiral ligands. In contrast, the number of successful examples of the asymmetric allylic alkylation of acyclic and unsymmetric allylic esters is relatively limited. 

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