Enantioselective Synthesis of β-Dibenzylamino Alcohols via a Dynamic Kinetic Resolution of α-Halo Acids
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O'Meara, Jeff A.,Gardee, Nizar,Jung, Manfred,Ben, Robert N.,Durst, Tony
p. 3117 - 3119
(2007/10/03)
Stereospecific Amination by Dynamic Kinetic Resolution Utilizing 2-Oxoimidazolidine-4-carboxylate as a Novel Chiral Auxiliary
A novel type of stereospecific amination by dynamic kinetic resolution using (4S)-2-oxoimidazolidine-4-carboxylate (1) as a chiral auxiliary was developed. A reaction of a diastereomeric mixture of (4S)-3--2-oxoimidazolidine-4-carboxylates 4 with an amine in the presence of a base in HMPA predominantly afforded (4S)-3--2-oxoimidazolidine-4-carboxylates (S,R)-7 in good yields.The reaction proceeded by stereospecific SN2 type amination incorporated with rapid interconversion between the substrates (S,S)-4 and (S,R)-4.Mechanistic study suggested that the unique stereoselectivity was induced through the interaction between an amine and the ester group of (S,S)-4 in the transition state.The chiral auxiliary was easily removed with alkoxide anion to afford the α-amino acid synthon in good yields.