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

3.7, 10.7, 14.5Hz. BCHH), 0.76 (S. 3H, OB0 ester CCH3); I3c NMR (CDCls, 75 MHz) 6
171.1 (Cd), 156.4 (CONH), 136.3 (C~Z-%=), 128.5, 128.2, 128.1 (C~Z-a=), 108.0
(OB0 ester C-O), 72.7 (OB0 ester 0CH2), 67.0 (CbzD20), 59.3 (y-, 52.6 (a--CH),
52.1 (CO=), 32.2 (OB0 ester CCH3), 30.5 (fbW2), 14.2 (OB0 ester CcH3); IR (cast
from CHC13) 3432,2954,2883,2121, 1727,1515,1227, 1048,1016,909; ESI-MS (M +
H+) 421.03. Anal. calcd for Ci9H*4@: C, 54.28; H, 5.75; N, 13.33. Found: C, 54.48;
H, 5.98; N, 13.36.
4.4.37 Metbyl-(2S,AS)4-amin0-2-[(be~10xy)~bonyI]smin011-(4-methyI-2,6,7-
trioxabicycIo-[2.2.2]oct-1-y1)butanoate, Cbz-L-GIu(~NH2)(OMe)-O80 ester, 4.107.
Cbz-L-Glu(y-N3)(0Me)-OB0 ester 4.106 (0.032 g, 0.07 rnmol) was combined with PPh3
(24 mg, 0.09 mmol) and dissolved in dry THF (50 mL) then stirred at ambient
temperature for 24 hours. Distilled water (15 pi) was then aàded and the mixture
refluxed for 3 hours. The solvent was then removed under reduced pressure to give a
white solid which was purified by flash chromatography to give the desired product in
76% yield (21 mg).
TU= (9: 1, Et0Ac:MeOH:O.S % mH). Rf = 0.60; 'H NMR (Acetone-&, 300 MHz) 6
7.36-7.21 (m, 5H, ArH), 5.78 (d, lH, J = 10.4Hz, NH), 5.06 (d, IH, J = 12.7Hz,
CbzCHHO), 4.96 (d, 1 H, J = 12.7Hz, CbzCHHO), 4.1 1 (ôr dd 1 H, J = 3.4. 10.7Hz, y-
225