Aziridines imino ester synthesis

The key intermediate in the preparation of derivatives suitable for peptide synthesis (Table 3) is the benzyl (25)-7V-tritylaziridine-2-carboxylate, since it is smoothly converted into the N-protected imino acid by catalytic hydrogenolysis.[47] Similarly, the related methyl ester is saponified by lithium hydroxide to produce A-tritylaziridine-2-carboxylateJ83 84 Detrit-ylation to benzyl (2S)-aziridine-2-carboxylate is more difficult, but the dibenzosulfimide salt is found to be perfectly stable on storage as a solid for longer periods of time (see Section 9.2.1.1) J47l In solution, upon addition of bases the benzyl ester is sufficiently stable to allow for peptide syntheses.[47]... 

The memory of chirality concept has been employed in a strategy for the synthesis of chiral a,/ -diamino- and a-amino-/ -hydroxy ester derivatives via asymmetric imino-aldol and aldol reactions, starting from protected aminoesters. The route can 0 be extended to the enantioselective synthesis of aziridines. 

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