Abstract Enantiopure 5, 5-disubstituted t-butyl 2-t-butyl-3-methyl-4-oxoimidazolidine-1- carboxylates readily available by diastereoselective double alkylation of the parent compound (Boc-BMI) can be converted to α-branched α-amino acids with two bulky substituents (PhCH 2/Et, PhCH 2/i-Pr, PhCH 2/CH 2 C 6 H 11) in four simple steps: hydrolysis to the amino acid amides, N-benzoylation, cleavage of the amino acid amide ...