Trifunctional Amino Acids with Two Different Protectors

24 TRIFUNCTIONAL AMINO ACIDS WITH TWO DIFFERENT PROTECTORS 

FIGURE 6.30 Approaches for the synthesis of monosubstituted trifunctional amino acids. (A) Monoesterification of dicarboxylic acids. (B) Aa-Alkoxycarbonylation of lysine through the e-benzylidene derivative [Bezas Zervas, 1963]. (C) SelectiveN -detritylation of ditrityl derivatives.138 (D) A- AI ko x y met hy 1 at 10 n of histidine by displacement of AP-substituents.137 Cbz-His(CH2OR)-OMe are obtained from Cbz-His(xAc)-OMe. = Acylating reagent. 

FIGURE 6.31 Simultaneous protection of the amino and carboxyl groups of an amino acid by reaction (A) with copper(II) basic carbonate133 or acetate,134 giving the copper complex, (B) with triethyl borane giving the boroxazolidone,139 and (C) with dichlorodimethylsilane giving the dimethylsilyl derivative.138141 

A Neuberger, F Sanger. The availability of acetyl derivatives of lysine for growth. (H-Lys(Z)-OH from the copper(II) salt) Biochem J 37, 515, 1943. 

R Ledger, FHC Stewart. The preparation of substituted y-benzyl L-glutamates and 13-benzyl L-aspartates. (copper(II)) Aust J Chem 18, 1477, 1965. 

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