A versatile and practical route to both enantiomers of a wide variety of 4-substituted 2-oxazolidinones from the parent heterocycle is provided by regioselective substitutions via 4-methoxy derivative followed by chromatographic separation of the diastereomers derived from N-2-exo-methoxy-1-apocamphanecarbonylation.
5-dimethoxy-2-imidazolidinone derivatives, which are readily accessible from simple 1,3-dihydro-2-imidazolone heterocycles, represent good candidates for a newclass of chiral synthons for use in the preparation of optically active threo-diamines such as 2S,3R- and 3S,4S-diamino carboxylic acids.
Enantiomeric [4+2] cycloadduct-based 2-oxazolidinones (3a and4a), newly derived from 9,10-dimethylanthracene and 2-oxazolone, serve as the most effective Evans' auxiliaries so far developed in diastereoselective alkylations and Diels-Alder reactions.
Highly enantioselective transferhydrogenation of ketimines to the corresponding chiral amines was achieved with the chiral Ru(II) complex, prepared from the conformationally rigid and sterically bulky "roofed" cis-1,2-diamine.
The "roofed" chiral 2-thiazolidinones, which are sterically congested and conformational rigid, and which are perpared by the [4+2] cycloaddition of 2-thiazolone to the cyclic dienes, dimethylanthracene and hexamethylcyclopentadiene, followed by optical resolution with (1S, 2R)-2-methyoxy-1-apocamphanecarbonic acid (MAC acid) are of considerable promise for use as chiral auxiliaries for the alkylation of enolates.