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

duodomethane (0.376 g, 4.67 mmol) and trimethylalurninum (0.47 mL, 0.94 mmol, 2.OM
in hexanes) in dry THF (10 mi,) under Ar. The mixture was stirred at room temperature
for 4 h before cold saturated potassium tartrate (10 mL) was added. The resulting
queous layer was extracted with EtOAc (3 x 40 mL), the organic layers were pooled and
extracted with 3% -1 (2 x 25 mL), IO % NaHC03 (25 mL), saturated NaCl (25 mL)
and dned over MgSQ. The solvent was removed under reduced pressure and the
resulting slightly yellow oil purified by flash chromatography (Et0Ac:Hex 1: 1) to give a
clear oil which was crystallized from Et2Ohexanes to give 0.35 g of 3.38 (76% yield).
mp 73-74°C; [al2O~ = -66.5 (c = 0.9, EtOAc); TLC (1 : 1 EtOAcHex). Rr = 0.48; ' H NMR
(CD% 250 MHz) 6 7.34-7.25 (m. 5& ArH), 5.92 (ddd, lH, J = 5.5, 10.5, 1 7.2Hz, P-
CH), 5.3 1-5.06 (m, 3H, NH, y-C&), 5.12 (S. 2H. CbzCW), 4.43 (br t, 1 H, J = 6.9Hz,
a-CH), 3.89 (s, 6H, OB0 ester CHzO), 0.78 (s, 3H, OB0 ester CCH3); 13c NMR (CDC13,
63 MHz) 6 156.0 (CONH), 136.5 (m), 133.2 (CH=CH2), 128.4, 128.0, 128.0
(Ar=cH), 1 16.7 (CH=w2), 10S.O (OB0 ester C-O), 72.8 (OB0 ester CH20), 67.8
(Cbz-20), 57.1 (a-GH), 30.7 (OB0 ester mH3), 14.3 (OB0 ester CcH3); IR (cast
from CH2C12) 3371,3064, 3033, 2944,2881, 1722, 1646, 1515, 1397, 1336, 1223, 1053
cm-'; ESI-MS (M + HC) 318.91; Anal. Calcd for Ci7H2iNOs: C, 63.94; H, 6.64; N. 4.39.
Found: C, 64.09; H, 6.73; N, 4.36.