The range and scope of the oxidative oxazoline-oxazinone rearrangement-hydrogenation sequence (OOOH)--a short, direct asymmetric synthesis of α-amino acids from carboxylic acids--was explored. The highest yet reported diastereoselectivity for hydrogenation of the oxazinone C=N bond (d.r.=>80:1) is disclosed and rationalized with the aid of ab initio molecular calculations.
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