Amino acids
Amino acids U 0400Asymmetric Synthesis with 6-tert-Butyl-5-methoxy-6-methyl-3,6-dihydro-2H-1,4-oxazin-2-one as a New Chiral Glycine Equivalent: Preparation of Enantiomerically Pure α-Tertiary and α-Quaternary α-Amino Acids. -The synthetic utility of oxazinone (V) as key intermediate in the synthesis of enantiomerically pure α-amino acids is studied. Oxazinone is prepared from α-hydroxy acid (I), itself obtained in excellent optical purity by optical resolution using (R)-phenylalaninol. Monoalkylation, dialkylation and cyclopropanation reactions of oxazinone (V) proceed with excellent yields and diastereoselectivities. The cyclopropanation reaction with epichlorohydrin enantiomers (XII), however, does not proceed with the expected stereoselectivity and cannot be used to achieve all four possible diastereomers. Further functionalization of the cyclopropane side chain is studied. Hydrolysis conditions for the release of the corresponding α-amino acids from the oxazinones are optimized for each substrate. In contrast to a previously described oxazinone (XXIII), no side reactions due to additional functional groups are possible. -(KOCH, C.-J.; SIMONYIOVA, S.; PABEL, J.; KAERTNER, A.; POLBORN, K.; WANNER*, K. T.; Eur.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.