Synthetic 2-Amino Alcohol Derivatives as Chiral Auxiliaries

Abstract

Both enantiomers of cis-4, 5-disubstituted 2-oxazolidinones, DHAOx (4, 5-(9, 10-dihydroanthraceno)oxazolidin-2-one), DMAOx (4, 5-(9, 10-dihydro-9, 10-dimethylanthraceno)oxazolidin-2-one), CPAOx (4, 5-(1, 4-cyclopentano)oxazolidin-2-one), HMCOx (4, 5-[3, 5-(1, 2, 3, 4, 4, 5-hexamethyl-1, 4-cyclopenteno)]-oxazolidin-2-one) and BPSOx (4, 5-[1, 4(2-terf-butyldiphenylsilyloxy)cyclopenteno] oxazolidine-2-one), which are sterically congested and conformationally fixed by bicyclo [2.2.1] and [2.2.2] ring systems are newly prepared by the Diels-Alder reactions of 2-oxazolone with the cyclic dienes such as anthracenes and cyclopentadienes followed by optical resolution with MAC acid (2-methoxy-1-apocamphanecarboxylic acid). These compounds, particularly DMAOx, HMCOx and BPSOx, serve well as the most powerful 2-oxazolidinone chiral auxiliaries reported so far for the asymmetric reactions such as alkylations, the Diels-Alder reactions, the Michael-type additions and aldol reactions. Sterically congested 2-aminoalcohol derivatives derived from the ringopening of these 2-oxazolidinones are shown to be highly useful auxiliaries for enantioselective additions of diethylzinc to aldehydes and enantiodivergent canversion of meso-dicarboxylic anhydrides to chiral half-esters.