NEW CHIRAL AUXILIARIES BASED ON CONFORMATION CONTROL, A C-2-SYMMETRICAL 2,2-DIMETHYLIMIDAZOLIDINE AND 4-CHIRAL 2,2-DIALKYLOXAZOLIDINES - SYNTHESIS AND CONFORMATIONAL-ANALYSIS OF ACRYLAMIDE DERIVATIVES

New chirality-controlling auxiliaries, a C2-symmetric 2,2-dimethylimidazolidine and 4-chiral 2,2-dialkyloxazolidines, are readily prepared from a C2-SYMMetriC 1,2-ethanediamine and naturally occurring alpha-amino acids, respectively. Conformational analysis of their N-acryloyl derivatives has been carried out on the basis of dynamic H-1 NMR spectroscopy and molecular mechanics calculations using MM2 program. Proper choice of the substituents at 2-, 4-, and 5-positions, in the oxazolidine cases, leads to the most effective chiral shielding of a diastereotopic acryloyl face.