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

TLC (9: 1, Et0Ac:MeOH 0.5% N'&OH); 'H NMR (Acetone-&, 300 MHz) 6 7.37-7.24
(m, 5H, ArH), 5.64 (d, lH, J = lO.lHz, NH), 5.1 1 (m. 2H, CbzC&O), 4.21-3.75 (m + s,
8H, a-CH, B-CH, OB0 ester CH&)), 3.69 (s, 3H, CO2CH3), 0.83 (s, 3H, OB0 ester
CC&); "C NMR (Acetone-6, 75 MHz) 6 172.3 cd), 156.1 (CONH), 137.4,
(Cbz=C=), 128.3, 127.9, 127.7 (Ch-=), 108.4 (OB0 ester C-O), 72.3 (OB0 ester
- CHtO), 65.8 (Cbz_CD), 59.8 (B-H), 52.3 (a-CH), 51.2 (Corn3), 32.4 (OB0 ester
-
CCH3), 13.6 (OB0 ester CC&); ESI-MS (M + H+) 380.94; And. calcd for Cl&&@:
C, 56.84; H, 6.36; N, 7.36. Found: C, 57.13; H, 6.85; N, 7.42.
5.4.23 (2S)-2,34i~obutanedioie acid, Asp(p-NHz)OH, 5.6.
Same procedure as in section 5.4.14 to give 0.029 g (62%) of 5.5.
1
H NMR m20, 300 MHz) 6 4.09,4.00, 3.75, 3.69 (d, IH, J = 3.4Hz, 8-CH, a-CH); I3c
NMR @20, 75 MHz) 6 174.0 (@O), 173.8 c=0), 62.0,61.5 (a-CH, B-CH); ESI-MS
148.87.