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)]-oxaz olidin-2-one) and BPSOx (4,5-[1,4-(2-tert-butyldiphenylsilyloxy)cyclopenteno]oxazoli dine-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 ring-opening of these 2-oxazolidinones are shown to be highly useful auxiliaries for enantioselective additions of diethylzinc to aldehydes and enantiodivergent conversion of meso-dicarboxylic anhydrides to chiral half-esters.