Enantioselective alkylation at the α-position of cyclic ketones using a chiral lithium amide as a base in the presence of lithium bromide

An efficient enantioselective alkylation reaction at the α-position of cyclic ketones (1, 2) can be realized in up to 92% enantiometric excess (e.e.) by first forming their lithium enolates using a chiral lithium amide 4 in the presence of lithium bromide, followed by treatment with alkyl halides.