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

CHD), 3.7 1-3.67 (m, lH, B-CHH), 2.60 (br s, IH, OH), 0.8 1 (S. 3H, OB0 ester CC&);
13c NMR (-13, 62.9 MHz) 6 156.3 GONH), 136.4 (Ar=-), 128.4, 128.0, 127.9
( ,
108.0 (OB0 ester O ), 72.7 (OB0 ester ÇHzO), 66.9 (-H20), 6 1.9 (8-
- CH2), 55.3 (a-CH), 30.5 (OB0 ester CCH3), 14.2 (OB0 ester CCH3); IR (cast from
CH2Cl2) 3407,3063,3033,2948,2883,1716,1607, 1586,1527,1399,1352, 1237, 1048,
1010 cm-'; HRMS (FAB) caiculated for (M + H?) C16HuN06: 324.1447. Found:
324.1435; bai. Calcd for C16H21N06: C, 59.43; H, 6.55; N, 4.33. Found: C, 59.43; H,
6.64; N, 4.34.
3.43 l-[N-(Benzy10xy~ny~)-(lS)Il-aminol21o~oetbyl]4-methyl-2,6,7-tri0~8-
bicyclo[2.2.2]0ctane, Cbz-L-Ser(dd)lOBO ester, 337.
Cbz-Ser OB0 ester 3.41 (9.04 g, 27.86 mol) was dissolved in freshly distilled CH2CI2
(80 mL) under Ar and cooled to -7g0C in flask 1. Oxaiyl chloride (3.89 mL, 44.58 mrnol,
1.60 equiv) was added to CHzCb (120 mL) in a separate round bottom flask (flask 2)
under Ar, and cooled to -7g°C. Dry DMSO (7.03 mL, 91.94 mrnol, 3.30 equiv) was
added quickly (to prevent freezing in the syringe) to the oxalyl chloride solution (flask 2
- taking care to release the evolved gas) and the mixture was stirred at -7g0C for 15
minutes. The alcohol solution was transferred slowly by cannula to flask 2 over a period
of 30 minutes and then rinsed with CH2C12 (50 mL). The resulting cloudy, white mixture
was stirred for 1.5 hours at -7S°C. DPEA (24.27 mL, 0.14 mol) was added and the
solution stirred for 30 minutes at -78OC and 10 minutes at 0°C. Ice-cold CHXl2 (250
rnL) was added and the solution was washed with ice-cold 3% NaCl (3 x 250 d),
brine (250 mL) and dried over MgS04 before being evaporated to dryness. The reaction