| 摘要 |
An improved process for making chiral, alpha -methylated, alpha -substituted amino acids of the formula I wherein Y is a hydrogen atom and R2 is the residue of a natural or unnatural amino acid, in which process an oxazolidinone of the formula II is formed by reacting a protected amino acid of the formula IA wherein Y is a protecting group, with an aldehyde of the formula RCHO, or an equivalent thereof, in the presence of a chlorinating agent and a Lewis acid. The group R2 is introduced into the oxazolidinone intermediate of formula II in a conventional manner, and subsequent hydrolysis and deprotection, both carried out in a conventional manner, yield the chiral, alpha -methylated, alpha -substituted amino acid.
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