Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

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generation of the enolate and addition of an allcyl halide is followed by decarboxylation
to give the racemic amino acid.
1) Base
m\ -2-
Scheme 1.4
S imilar methodology emplo ys glycine Schiff bases (or a-isoc yanoacetates) whic h
are alkylated to a number of mono- and di-alkylated amino acids obtained in 50-90%
yield from the benzylidene derivative of glycine ethyl ester 1.5 (Scheme 1 S)."
P~CH=N"CO~E~
Scheme 1.5
- 1) LDA or KOBu R ' alkaline
2) R'X hydrolysis R'
rn PhCH= &C02Et
H2
1.2.3 Other Synrhetic Routes to Racemic a-Amino Acids
Numerous specific methods exist for the synthesis of racernic arnino acids as a
survey of the literature, especially pre-1970's, indicates. Included amongst these is the
classic Cunius rearrangement and the many modifications employed to synthesize a large
number of both proteinogenic and non-proteinogenic a-arnino acids."
1.3 Synthesis of Optidy Active a-Amino Acids
Optically active a-amino acids were initially obtained by the resolution of
racemic mixtures, either by crystallization of diastereomeric salts, through derivatization