A Simple Procedure for the Transformation of l-Glutamic Acid into the Corresponding γ-Aldehyde

Abstract

2-Dibenzylamino-5-oxopentanoic acid benzyl ester has been obtained in good yields by complete benzylation of l-glutamic acid in NaOH and Na₂CO₃, selective reduction of the γ-ester into alcohol with DIBAL and further transformation into aldehyde using Swern oxidation. The overall three-step procedure from Glu gave aldehyde in 49% yield.

aldehydes - amino acids - reductions - oxidations - protecting groups

References

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Recent examples:

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Compound 2 has been reported in the reaction schemes of the previously cited paper without any detailed description for its preparation. Also in a more detailed article compound 2 was cited but not described. In these papers, the reference to the preparation of tetrabenzyl glutamic acid 2 reported to a paper where the preparation of the corresponding derivative of aspartic acid was described without any experimental procedure:

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<A NAME="RZ10904SS-8B">8b</A>

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<A NAME="RZ10904SS-12">12</A>

When DIBAL came from a new bottle, 2 equiv were sufficient to obtain good yields. When DIBAL came from a previously opened bottle, we found that it was better to use 3 equiv. It is also possible to make further additions of DIBAL at 0 °C until the starting material disappears.