Regioselective opening of N-Cbz glutamic and aspartic anhydrides with carbon nucleophiles

Depending on the experimental conditions, aspartic and glutamic anhydrides can be opened regioselectively with Grignard reagents, thus giving access to different isomers of chiral amino-ketoesters.

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(4S)-Methyl 4-(benzyloxycarbonylamino)-5-oxo-5-phenylpentanoateC20H21NO5[α]D20=+29.0 (c 1, CH2Cl2)

(4S)-Methyl 4-(benzyloxycarbonylamino)-5-oxononanoateC18H25NO5[α]D20=+24.4 (c 1, CH2Cl2)

(4S)-Methyl 4-(benzyloxycarbonylamino)-5-(3-methoxyphenyl)-5-oxopentanoateC21H23NO6[α]D20=+23.6 (c 1, CH2Cl2)

(4S)-Methyl 4-(benzyloxycarbonylamino)-5-oxoundecanoateC20H29NO5[α]D20=+13.1 (c 1, CH2Cl2)

(S)-tert-Butyl 2-(benzyloxycarbonylamino)-5-oxo-5-phenylpentanoateC18H25NO5[α]D20=+6.8 (c 0.45, CHCl3)