The title compound BDI is prepared on multigram scale, so clean that highly efficient in-situ double alkylations are feasible, in which the sequence of addition of the two either by resolution of the precursor 2-tert-butylimidazolidin-4-one (from glycine amide and pivalaldehyde) through different electrophiles determines the configuration at the newly formed stereogenic center (Scheme 5). In contrast to diastereomeric salts (Scheme 2) or by preparative chromatographic enantiomer separation on a chiral column. derivatives of previously reported chiral glycine reagents, the products from BDI are converted to methyl esters of amino Lithiated BDI derivatives are highly nucleophilic species, combining the structural elements of a Li enaminate, of an acids under mild conditions and without concomitant formation (... and the need for recovery or removal) of a chiral enolether and of an N-Boc-enaminate (E, G). They react with complete diastereoselectivity (NMR analysis) from the face auxiliary; the method is compatible with acid-sensitive side chains in the α-amino acids and α-branched α-amino acids trans to the tert-butyl group. The electrophiles employed are primary and secondary alkyl, allyl, benzyl, and propargyl to be synthesized (Schemes 4 and 6). The addition of Li-BDI to aldehydes furnishes, after hydrolysis, α-amino-β-hydroxy halides (Schemes 3 and 5), enoates (in Michael additions, Scheme 7), as well as aliphatic and aromatic aldehydes (in acids of erythro configuration (allo-threonine analogs, Scheme 8); a model for the stereochemical course of this aldol additions, Scheme 8). When a third, exocyclic, stereocenter is formed in these reactions, there is a high reaction (rel. topicity unlike) is proposed, and compared with the corresponding conversions of analogous oxazolidinone degree of enantiomer differentiation (with rac. sec. halides, products 10-12) and of enantiotopic face differentiation (with and imidazolidinone Li enolates which occur with rel. topicity like. enoates and aldehydes, products 40-50). The reactions are