New Efficient Strategy for the Incorporation of (S)-Isoserine into Peptides

Medicinal Chemistry of α‐Hydroxy‐β‐Amino Acids

“…Then, a primary amine was generated from the b-carboxy group by the Curtius procedure via azide 6 and isocyanate [7]. Burger et al applied hexafluoroacetone as a protecting and activating reagent in the reaction with (S)-malic acid (3b) [8]. To obtain the isocyanate 8 they treated the acid chloride of 7 with trimethylsilyl azide.…”

Synthesis of Ureido-Linked Glycosylated Amino Acids from N α-Fmoc-Asp/Glu-5-oxazolidinones and Their Application to Neoglycopeptide Synthesis

“…[6] This protocol is useful particularly for N a -methyl amino acids, [7] a-hydroxy acids, [8] and amercapto acids. [9] However, it cannot be extended to obtain isocyanates of HFA-protected activated a-amino acids because of intramolecular trapping of the generated x isocyanates by the ÀNH of the oxazolidinone ring.…”

Hexafluoroacetone as protecting and activating reagent: reactions of hexafluoroacetone with α-keto acids

“…o-Activation provides access to libraries of a-amino, a-hydroxy and a-mercapto acids of high structural diversity. Excellent yields are obtained via acid chlorides [12], isocyanates [13], diazo ketones [9,10,14] and bromo ketones [9,10,15] (Scheme 1). Now we report on experiments to apply the hexafluoroacetone protection/activation concept to a-oxo-o-carboxy carboxylic acids with the objective to develop a preparatively simple general access to a-keto acids, which have been used for peptide modification only recently [16].…”