M. Oba et al. / Tetrahedron: Asymmetry 17 (2006) 1890–1894
1893
3.61 (dd, J = 11 and 5 Hz, 1H), 3.68 (dd, J = 11 and 4 Hz,
1H), 3.87 (br s, 1H), 4.18 (d, J = 5 Hz, 1H), 4.59 (br s, 1H).
13C NMR (CDCl3) d 20.80, 28.30, 51.00, 61.84, 62.73 (t,
J = 23 Hz), 79.93, 155.79, 171.46. HRMS (EI, 70 eV) m/z
235.1378 [(M+H)+, calcd for C10H19DNO5 235.1374].
4.1.10. (2S,3R)-N-tert-Butoxycarbonyl-O3-(4-toluenesulfon-
yl)[3-2H]serine tert-butyl ester 11. To a solution of com-
pound 10 (2.93 g, 11.2 mmol) in pyridine (10 mL) was
added 4-toluenesulfonyl chloride (3.00 g, 15.7 mmol) at
0 °C and the solution was refrigerated overnight. The mix-
ture was quenched with water (10 mL) and extracted with
ethyl acetate. The organic layer was washed successively
with 1 M HCl, water, and brine, and dried over MgSO4.
After removal of the solvent, the residue was chromato-
graphed on silica gel. Elution with a mixture of hexane
and ethyl acetate (80:20) afforded the title compound 11
(3.21 g, 69%) as colorless needles (hexane), mp 90–92 °C.
1H NMR (CDCl3) d 1.40 (s, 9H), 1.43 (s, 9H), 2.44 (s,
3H), 4.35–4.38 (m, 2H), 5.26 (br d, J = 7 Hz, 1H), 7.34
(d, J = 8 Hz, 2H), 7.76 (d, J = 8 Hz, 2H). 13C NMR
(CDCl3) d 21.87, 28.03, 28.45, 53.49, 64.93 (t, J = 24 Hz),
80.38, 83.54, 128.19, 130.14, 132.67, 145.29, 155.21,
167.60. HRMS (EI) m/z 417.1835 [(M+H)+, calcd for
C19H29DNO7S 417.1806].
4.1.6. (2S,3R)-N-tert-Butoxycarbonyl-O3-acetyl[3-2H]serine
7. To a suspension of sodium metaperiodate (40.0 g,
187 mmol) and RuCl3ÆnH2O (1.21 g) in H2O (100 mL)
was added a solution of compound 6 (3.81 g, 16.3 mmol)
in acetone (100 mL). The resulting two-phase mixture
was vigorously stirred at room temperature for 1.5 h. The
layers were separated. To the organic phase was added 2-
propanol (50 mL) and the mixture was stirred for 1 h. After
removal of the precipitated RuO2 using a Celite pad, the
filtrate was extracted with chloroform and dried over
MgSO4. Evaporation of the solvent gave a quantitative
yield of the title compound 7 (4.04 g) as a colorless oil.
1H NMR (CDCl3) d 1.46 (s, 9H), 2.18 (s, 3H), 4.46 (d,
J = 3 Hz, 1H), 4.59 (dd, J = 9 and 3 Hz, 1H), 5.31 (d,
J = 9 Hz, 1H).
4.1.11. (2R,3S)-N-tert-Butoxycarbonyl-S-acetyl[3-2H]cys-
tine tert-butyl ester 12. To a solution of compound 11
(979 mg, 2.35 mmol) in DMF (5 mL) was added potassium
thioacetate (442 mg, 3.87 mmol) under an argon atmo-
sphere at 0 °C and the mixture was stirred at room temper-
ature overnight. After removal of the solvent, the residue
was extracted with ethyl acetate and the organic phase
was washed with water and brine, dried over MgSO4,
and concentrated. The crude product was purified by flash
column chromatography on silica gel. Elution with a mix-
ture of hexane and ethyl acetate (80:20) gave 95% yield of
the title compound 12 (712 mg, 2.22 mmol) as colorless
4.1.7. (2S,3R)-[3-2H]Serine 8. Deprotection of compound
7 (505 mg, 2.03 mmol) was carried out in refluxing 6 M
HCl (20 mL) overnight followed by treatment with
DOWEXÒ 50WX8-400 to give (2S,3R)-[3-2H]serine
(8, 157 mg, 73%) as a colorless solid, mp 237 °C dec
23
(lit.26 228 °C dec). ½aꢁD ¼ þ15:4 (c 1.0, 1 M HCl) {lit.26
25
1
½aꢁD ¼ þ14:95 (c 9.34, 1 M HCl)}. H NMR (10% DCl in
D2O) d 3.56 (d, J = 4 Hz, 1H), 3.72 (d, J = 4 Hz, 1H).
13C NMR (D2O) d 56.40, 59.95 (t, J = 22 Hz), 172.49.
4.1.8. (2S,3R)-N-tert-Butoxycarbonyl-O3-acetyl[3-2H]serine
tert-butyl ester 9. To a refluxing solution of compound 7
(4.04 g, 16.3 mmol) in benzene (60 mL) was added a
mixture of N,N-dimethylformamide dineopentyl acetal
(7.38 g, 31.9 mmol) and tert-butyl alcohol (3.73 g,
50.3 mmol) and the reaction mixture was stirred for 2 h.
Then the cooled reaction mixture was diluted with ethyl
acetate, washed with saturated aqueous NaHCO3 and
brine, and dried over MgSO4. After removal of the solvent,
the residue was chromatographed on silica gel. Elution
with a mixture of hexane and ethyl acetate (90:10) afforded
the title compound 9 (3.77 g, 76%) as a colorless oil.
needles (hexane), mp 47–50 °C. H NMR (CDCl3) d 1.44
1
(br s, 9H), 1.46 (br s, 9H), 2.34 (s, 3H), 3.39 (br d,
J = 4 Hz, 1H), 4.41 (br dd, J = 7 and 4 Hz, 1H), 5.20 (br
d, J = 7 Hz, 1H). 13C NMR (CDCl3) d 28.12, 28.52,
30.75, 31.40 (t, J = 22 Hz), 53.79, 80.05, 82.83, 155.36,
169.66, 194.68. HRMS (EI) m/z 321.1644 [(M+H)+, calcd
for C14H25DNO5S 321.1594].
4.1.12. (2R,20R,3S,30S)-[3,30-2H2]Cystine 13. A solution
of compound 12 (609 mg, 1.90 mmol) in 6 M HCl
(20 mL) was refluxed overnight. The cooled reaction mix-
ture was washed with chloroform and concentrated. The
residue was treated with an ion-exchange resin (DOWEXÒ
50WX8-400) and the adsorbed amino acid was eluted with
1 M ammonia solution. The fractions, which gave a posi-
tive ninhydrin reaction, were combined, aerated overnight,
and concentrated to give 63% yield of the title compound
26
1
½aꢁD ¼ þ24:05 (c 1.0, CHCl3). H NMR (CDCl3) d 1.45
(s, 9H), 1.46 (s, 9H), 2.05 (s, 3H), 4.43–4.45 (m, 2H), 5.28
(br d, J = 7 Hz, 1H). 13C NMR (CDCl3) d 20.89, 28.13,
28.52, 53.56, 64.67 (t, J = 24 Hz), 80.29, 82.93, 155.44,
168.96, 170.76. HRMS (EI, 70 eV) m/z 305.1826
[(M+H)+, calcd for C14H25DNO6 305.1823].
13 (143 mg, 0.595 mmol) as a colorless solid, mp >250 °C
23
(lit.27 260–261 °C dec (sealed tube)). ½aꢁD ¼ ꢀ220:0 (c 0.1,
20
4.1.9. (2S,3R)-N-tert-Butoxycarbonyl[3-2H]serine tert-butyl
1 M HCl) (lit.27 ½aꢁD ¼ ꢀ223:4 (c 1.0, 1 M HCl)). 1H
ester 10. To
a
solution of compound
9
(3.76 g,
NMR (2.5% NaOD–D2O) d 3.01 (d, J = 4 Hz, 1H), 3.49
(d, J = 4 Hz, 1H). 13C NMR (2.5% NaOD–D2O) d 46.05
(t, J = 22 Hz), 57.59, 183.60.
12.4 mmol) in THF (60 mL) was added a solution of LiOH
(505 mg, 12.0 mmol) in H2O (45 mL). After being stirred
for an additional 2 h, the mixture was extracted with ethyl
acetate. The organic layer was washed successively with
water and brine, dried over MgSO4, and concentrated to
afford the title compound 10 (2.93 g, 90%) as a colorless
Acknowledgments
1
oil. H NMR (CDCl3) d 1.45 (s, 9H), 1.48 (s, 9H), 2.31
This work has been supported by CREST (Core Research
for Evolutional Science and Technology) of Japan Science
and Technology Corporation (JST). We also thank
(br s, 1H), 3.87 (d, J = 4 Hz, 1H), 4.25 (m, 1H), 5.41 (m,
1H).