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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 4.16<br />

The first synthesis <strong>of</strong> p,y-dihydroxyglutamic acid 4.9 has only recentiy been<br />

reported." 2S73S,4S-Dihydroxyglutamic acid 4-57 was synthesized from a D-ribose<br />

derivative 4-55 via an aziridino-y-lactone 4.56 in a Iengthy procedure <strong>and</strong> 3% overall<br />

yield (15 steps) (Scheme 4.17). Phannacological studies have shown 4-57 to be an<br />

agonist against mGIu 1 <strong>and</strong> weak agonist <strong>of</strong> mGlu 4?<br />

Scheme 4.17<br />

The synthesis <strong>of</strong> (2S,3S94R)-dihydroxyglutamic acid 4-59 followed shortly<br />

thereafter using a strategy essentially opposite that used for the synthesis <strong>of</strong> the 4S<br />

stereoisomer." An epoxy-pyrrolidinone template 4-58 derived fiom S-pyroglutaminol<br />

(4.48, &OH, R'=CO~H) gave the desired product 4.59 in 50% overall yield over 7 steps.

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