Syntheses of highly constrained β-aryl isohexanoic acid derivatives via asymmetric Michael addition

A series of enantiomerically pure highly sterically hindered β-branched isohexanoic acid derivatives have been synthesized with high diastereoselectivity via asymmetric Michael addition. The X-ray crystal structure of (4S,3'S)-3-[3'-(2,6-dimethylphenyl)isohexanyl]-4-phenyl-2-oxazolidinon e demonstrated that the β-configuration was induced from the Si-face, and that the torsional angle χ₂ was restricted by the bulky β-isopropyl group to the range expected from molecular modeling.