4-Amino-1-oxyl-2,2,6,6-tetramethylpiperidine-3-carboxylic acid (β-TOAC), the first spin-labelled, cyclic, chiral β-amino acid resolved in an enantiomerically pure state

Abstract

Amination of 3-carboxymethyl-1-oxyl-2,2,6,6-tetramethyl-4-piperidone with ( R)-α-methylbenzylamine, NaBH 3CN reduction of the resulting enamine and removal of the chiral auxiliary from the separated diastereoisomers, led to enantiomerically pure (3 S,4 S) and (3 R,4 R) methyl 4-amino-1-oxyl-2,2,6,6-tetramethylpiperidine-3-carboxylates.