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

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

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Scheme 4.10<br />

C02Et CO*Et<br />

R=Me, Et, Ph bc b c<br />

R'= H, Me. Et<br />

4.35 4.36 4.37<br />

Both the meso <strong>and</strong> 2R,4R forms <strong>of</strong> pminoglutamic acid have been synthesized<br />

using Garner's aldehyde 1.53 (Scheme 1.24) to generate either an E 4.38 or Z 4.39 olefin<br />

which is subsequently hydrogenated to give almost exclusively one stereoisomer?' In the<br />

case <strong>of</strong> 4.38, a ratio <strong>of</strong> 955 for 4AO:4A1 (Scheme 4.1 1, lefi-h<strong>and</strong> side) <strong>and</strong> for 439, a<br />

ratio <strong>of</strong> 94:6 for 4.41:4.40 (Scheme 4.1 1, right-h<strong>and</strong> side). nreso-2,4-Diaminoglutamic<br />

acid 4.42 was generated in 45% overall yield fiom the aldehyde 1.53 although no overail<br />

yield was given for the 2R,4R derivative.<br />

Scheme 4.11<br />

1 1)<br />

CSA, MeOH. R<br />

2) Jones ortidation<br />

3) C M<br />

4)10 N HCI, A

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