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

1.73 (ddd, lH, J = 3.6, 9.3, 14.OHz, B-CHH), 1.16 (d, 3H, J= 6.7Hz, yCH3), 0.82 (s,
3H, OB0 ester CC&); NMR (Acetone*, 75 MHz) 6 176.5 ad), 156.4 (CONH),
137.6 (Cb-), 128.3, 127.7, 127.7 (Cbz===), 108.3 (OB0 ester -O), 72.4 (OB0
ester CHD), 65.8 (CbzCH20), 53.0 (a--H), 50.9 (CW3), 35.8 (y-, 33.3 (OB0
ester CC&), 30.3 (B-m2), 15.9 (ym3), 13.4 (OB0 ester Cw3); IR (cast from CHCI,)
3330, 2958, 2877, 1714, 153 1, 1214, 1061,978,752; HRMS (FAB) calcd for (M +
C20Hd07 394.1 8658, found 394.18465. Anal. calcd for C&N@: C, 6 1 -06; H, 6.84;
N, 3.56. Found: C, 60.87; H, 6.84; N, 3.43.
trio~bi~y~10[2~2.2]0~t-l-yl)pentan01ite, Cbz-L-Glu(pMe)(OMe)-OBO ester, 4.74
Cbz-L-Glu(y-Me)(OMe)OBO ester 4.73 (0.177 g, 0.45 rnmol) was dissolved in dry THF
(25 mL) and cooled to -78°C under Ar. LDA (9 mL, 9.00 mmol) was added by syringe
and the mixture stirred for 1 h at -78OC before king poured into Et20 (100 mL) and
extracted with 3 1 NWl (25 mL), 1096NaHCO3 (25 mL), brine (25 mL) and the dried
over MgSO4. The solvent was removed under reduced pressure to give a light yellow oil
which was purified by flash chromatography (1: 1 Et0AC:hexanes) to give 79 mg of 4.73
(44% yield) and 85 mg of 4.74 (46% yield).
O F 3
TU3 (1: 1, EtOAc:Hex), Rf = 0.55; 'H NMR (Acetone-&, 300 MHz) 6 7.38-7.22 (m, SH,
Ar-H), 5.71 (d, lH, J= 10.3Hz. NH), 5.07 (d, lH, J= 12.7H.2, CbzCHHO), 4.98 (d, 1H, J
198