SYNTHESIS OF NEW b-AMINO ACID AND AMINOXY ACID
1773
treated with water (8 mL), and extracted with ether (2 × 10 mL). Organic layers were
washed with brine (10 mL) and dried (Na2SO4). Solvent was evaporated and the
residue purified by column chromatography (60- to 120-mesh silica gel, 10% ethyl
acetate in petroleum ether) to give 12 (0.10 g, 85%) as a colorless liquid. [a]20
¼
D
ꢀ132.11 (c 1.2, CHCl3); IR (KBr): n 2971, 2945, 2105, 1736, 1437, 1370, 1272,
1085, 976, 868, 751, 666 cmꢀ1; 1H NMR (CDCl3, 300 MHz): d 4.08 (d, 1H, J ¼ 11 Hz,
OCH), 4.01 (m, 1H, OCH), 3.77 (s, 3H, OCH3), 3.50 (t, 1H, J ¼ 11.4 Hz, OCH),
1.98–1.83 (m, 3H, CH2), 1.71–1.55 (m, 2H, CH2); 13C NMR (75 MHz, CDCl3): d
170.6, 80.3, 68.2, 53.1, 52.0, 27.9, 24.1; HRMS (ESI): m=z calculated for
C7H11N3O2Na [MþNa]þ 208.0613, found 208.0616.
(2S,3R)-Methyl 3-(tert-Butoxycarbonylamino)tetrahydro-2H-
pyran-2-carboxylate (1)
A mixture of 12 (0.08 g, 0.43 mmol) and 10% Pd-C (cat.) in MeOH (1.5 mL) was
stirred at room temperature under hydrogen atmosphere for 4 h. It was filtered and
washed with EtOAc (10 mL). The filtrate was evaporated under reduced pressure
to furnish amine 13, which was used for the next reaction without further purification.
To a solution of amine 13 in CH2Cl2 (10 mL), Et3N (0.15 mL, 0.99 mmol) and
(Boc)2O (0.17 mL, 0.75 mmol) were added at 0 °C and stirred for 5 h. The reaction
mixture was treated with water (10 mL) and extracted with CH2Cl2 (2 × 15 mL).
The organic layer was washed with brine (10 mL) and dried (Na2SO4). Solvent was
evaporated and purified the residue by column chromatography (60- to 120-mesh
silica gel, 12% ethyl acetate in petroleum ether) to furnish 1 (0.11 g, 85%) as
a colorless syrup; [a]20 ¼ ꢀ103.94, (c 1.2, CHCl3); IR (KBr): n 3290, 2975, 2936,
D
1754, 1705, 1540, 1446, 1370, 1290, 1209, 1175, 1115, 1094, 1066, 689 cmꢀ1
;
1H NMR (300 MHz, CDCl3): d (4.64 (brs, 1H, NH), 4.10–3.95 (m, 2H, OCH), 3.76
(s, 3H, COOCH3), 3.50–3.39 (m, 2H, OCH), 2.13–2.0 (m, 2H, OCH), 1.78–1.68
(m, 2H, CH2), 1.42 (s, 9H, Boc);13C NMR (75 MHz, CDCl3): d 170.1, 155.1, 80.1,
79.6, 66.7, 52.4, 48.2, 29.3, 28.3, 23.9; HRMS (ESI): m=z calculated for C12H21NO5Na
[MþNa]þ 282.1350, found 282.1352.
(3R,5R,6S,6R)(Allyloxy)2,2dimethylvinyltetrahydrofuro[2,3d][1,3]
dioxole (18)
Grubbs I catalyst (10 mol%) was added to a stirred solution of 16 (12.3 g,
54.42 mmol) in dry toluene (50 mL) and stirred at reflux for 3 h. The reaction mixture
was stirred for an additional 1 h at room temperature in open air. It was filtered through
celite and washed with toluene (2 × 20mL), and the solvent was evaporated. The residue
on purification by column chromatography (60- to 120-mesh silica gel, 10% ethyl
acetate in petroleum ether) afforded 18 (9.6g, 90%) as a brown syrup; [a]20 ¼ ꢀ 22.7
D
(c 0.1, CHCl3); IR (CHCl3): n 2987, 2937, 1737, 1645, 1449, 1288, 1163, 954, 831 cmꢀ1
;
1H NMR (300 MHz, CDCl3) d 6.0 (s, 2H, olefinic), 5.89 (d, 1H, J ¼ 3.7 Hz, C1H),
4.52 (d, 1H, J ¼ 3.7 Hz, C4H), 4.31 (m, 1H, C2H), 4.12 (m, 2H, OCH), 3.88 (d, 1H,
J ¼ 2.6 Hz, C3H), 1.48 (s, 3H, Me), 1.31(s, 3H, Me); 13C NMR (75 MHz, CDCl3)
d 131.7, 121.4, 111.1, 104.9, 84.1, 78.5, 70.6, 64.3, 26.5, 25.9; HRMS (ESI): m=z
calculated for C10H15O4[MþH]þ 199.0964, found 199.0963.