Inexpensive, multigram-scale preparation of an enantiopure cyclic nitrone via resolution at the hydroxylamine stage.
Résumé
The redn. of the chiral, racemic nitrone MiPNO provides a secondary hydroxylamine. Its O-acylation with O,O'-dibenzoyl-L-tartaric acid anhydride gives two diastereomers, that can be easily sepd. by selective dissoln. in orthogonal solvents. The recovery of the enantiopure nitrone is then carried out in a single step. The process allows the straightforward isolation of (R) and (S)-MiPNO in 57% and 38% yield, resp., from rac-MiPNO.