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A Simple Procedure for the Transformation of l-Glutamic Acid into the Corresponding γ-Aldehyde
21 October 2004 (online)
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
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The use of ionic liquids in reductive amination will be reported elsewhere.12
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.