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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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, HO-<br />

OH<br />

Scheme 3.14<br />

, 1) pb(OAc),<br />

2) Jones' reagent<br />

3) N2H4<br />

phthalimide<br />

3.7<br />

PhtN<br />

More recentiy, the same Dmannitol denved aldehyde 331 has been used to<br />

synthesize L-vinylglycine via imine 3.32 which was reacted with vinylmagnesium<br />

bromide to give amine 3.33 as one diastercorner (Scherne 3.25): Subsequent hinctional<br />

group manipulation gave L-vinylglycine in 45% yield over seven steps.<br />

NHBOC<br />

Scheme 3.15<br />

OH<br />

Hf32C-<br />

C<br />

2) Jones Oxidation NH~<br />

As discussed earlier (Section 1.3 A.2, Scheme 1 .Z), Gamer's aldehyde 153<br />

racemizes completely when treated with Ph3P%eBr'/~H.U However, the aldehyde may<br />

be used to generate p,y-unsaturated amino acids by Wittig reactions. Garner's aldehyde<br />

3.7

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