Selective alkylation/oxidation of N-substituted isoindolinone derivatives: synthesis of N-phthaloylated natural and unnatural ?-amino acid analogues.

ABSTRACT: The interchangeability of the isoindolinone group as a nitrogen protecting group for amino acid intermediates is demonstrated by the preparation of several natural and unnatural ?-amino acid derivatives using a two-carbon N-isoindolinone (phthalimidine) scaffold. Using a selective benzylic oxidation, the N-isoindolinone group is then converted to the N-phthaloyl group for convenient removal (65-98%). For preparation of the isoindolinone products which were to be the substrates for benzylic oxidation, a range of side chains were installed on the isoindolinone-protected glycine equivalent on deprotonation to demonstrate the utility of the N-protected isoindolinone synthon (51-93%). While the ensuing benzylic oxidation is employed successfully for converting the N-isoindolinone group to the N-phthaloyl group in simple substrates, substrates bearing unsaturated or electron-rich side chains respond poorly to the oxidation.

SUBMITTER: Patil PC 

PROVIDER: S-EPMC5722250 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature