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

Figure 1.1
Figure 1.2
Figure 2.1
Figure 2.2
Figure 3.1
Figure 3.2
Figure 4.1
Figure 4.2
Figure 4.3
Figure 4.4
Figure 4.5
Figure 4.6
Figure 4.7
Figure 4.8
Figure 4.9
Important Serine Aldeh yde Equivalents ................................................... 21
Selected Alanine $-Anion Equivalents ..................................................... 23
p-Hydroxy-a-Amino Acids in Various Biological Compounds ......... . 44
Felkin-Anh Mode1 Predicting re Face Attack on the Side Chain
Carbonyl of 2 4 and 2A7 ......................................................................... 71
Formation of the Oxazolidinone 3.46 ............................. . ............. 119
Assessrnent of enantiomenc purity after ion exchange purification of
L-vinylglycine obtained after deprotection of Cbz-L-Ser(CH2TMS)
OB0 ester 3.45 (left) and Cbz-L-Gly(CH=C&)OBO ester 3.38 ........... 120
Six-member chelated cyclic transition state ............................................ 151
300 MHz 'H-NMR of Cbz-L-Glu(y-Me)(OMe)OBO ester 4.73 ............ 157
X-Ray Crystal structure of Cbz-L-Glu(yMe)(OMe)OBO ester 4.73 ..... 159
3ûû MHz 'H-NMR of W R 4.74 (top) and 2s. 4S 4.73 (bottom)
Cbz-L-Glu(y-Me)(OMe)-OB ester ..................................................... 160
GCMS of 2S.4SCbz.L.Glu(y .CH3)(OMe)OB0 ester 4.73 (top) and
epimerized 2S.4RS .C bz-L-Glu(y-CH3)(OMe)OB O ester 4.73l4.74
(bottom) ................................................................................................... 161
Variable-Temperature 5 0 MHz ' H-NMR studies in toulene-dg
of Cbz-L-Glu(y-Me)(OMe)OBO ester 4.73 ..................... . ................... 164
(a) Anti versus Syn carbarnate isomers (b) Hydrogen bonding in
the Syn conformational isomer of 2s. 4S and 2s. 4R Cbz-L-Glu(y-
Me)(OMe)OBO ester 4.73 and 4.74 ...................................................... 166
X-Ray Crystd structure of Cbz-L-Glu(y-OH)(OMe)OBO ester 4.96 .... 172
Plot of Yield (%) versus Time (minutes) after quenching of
electrophilic azidation of Cbz-Glu(0Me)OBO ester 4.69 with
Tnsyl Azide A105 ........ .................... ....................................................... 176
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