Control of the enantioselectivity of alkylation of phenylalanine derivatives by regulation of the aggregate structure of chiral enolate intermediates

Two strategies were introduced for the control of enantioselectivity of alkylation of phenylalanine derivatives by regulation of the aggregate structure of chiral enolate intermediates. Use of amino acid-dimers, 6 and 15, was effective to minimize solvent- and electrophile-dependency of enantioselectivity of the alkylation. α-Allylation of 20 proceeded in improved selectivity of 82-88% ee under the control of aggregation of the intermediary enolate.