Reaction of a-Halo Acids with Hydroxylamine

The fact that substitution of bromine in compounds of type (127) with hydroxylamine is accompanied by Walden inversion led Noce et al. (158) to the first synthesis of optically active N-hydroxyamino acids L- and D-N-hydroxyleucine (66). The same method was later used to synthesize the aromatic D-amino acids N-hydroxytyrosine (35) and N-hydroxyphenylalanine (34) (159). Reaction of hydroxylamine with a,a -dibromopimelic acid gave l-hydroxy-2,6-piperidine dicarbox-ylic acid (134) (158). Shin (160) studied the reaction of esters (128) and (129) with hydroxylamine in the presence of triethylamine and obtained the ethyl (77) and tert miy (130) esters of N-hydroxyamino acids as oils. 

Anhydrous hydroxylamine which is explosive was used for the synthesis of alanosine (18) 161 N-hydroxylysine (74), N-hydroxyornithine (73) and lower homologues (136,137) 162). The ligand of amava-dine was synthesized as a racemate using this method (57). 

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