Research Information System
SYNLETT, vol.28, no.11, pp.1278-1281, 2017 (SCI-Expanded)
5-Substituted oxazinones provide N-protected beta(2)-amino acid esters upon alcoholytic ring opening. Thus far, this access to enantiopure beta(2)-amino acids has been restricted to the use of enzymes (hydrolases) as catalysts for the kinetic resolution of racemic 5-substituted oxazinones, and branched alkyl or ortho-substituted aryl groups on the substrate oxazinone's 5-position were typically not tolerated. We herein report that certain bifunctional chiral base/squaramide organocatalysts, in particular those derived from cis-1,2-diaminocyclohexane or 9-amino-9-epi-quinine, allow the first organocatalytic kinetic resolution of this 'difficult' class of oxazinone substrates, affording N-protected beta(2)-amino acid esters with selectivity factors up to 43.