LETTER
mL) and the organic layer was washed with sat. NaHCO3
Synthesis of (R)- and (S)-2-Furyloxirane
1621
argon atmosphere at r.t. After 30 min a solution of Li-TBS-
dithiane13 (1.2 equiv) in anhyd THF (2 mL) containing
HMPA (0.7 mL) was added at r.t. The reaction was
quenched after 2 h with sat. NH4Cl solution (10 mL) and
extracted with Et2O (20 mL). The organic layer was washed
with H2O (10 mL), brine (10 mL), dried (MgSO4), and
evaporated. The residue was further purified by column
chromatography on silica gel (PE–EtOAc, 50:1) affording 8
(122 mg, 50%; Rf = 0.5) and 9 (81 mg, 33%; Rf = 0.41).
Compound 8: [a]D20 +77.0 (c 0.5, CHCl3). 1H NMR (300
MHz, CDC13): d = 7.34–7.32 (m, 1 H), 6.30–6.27 (m, 1 H),
6.19–6.17 (m, 1 H), 4.96 (dd, J = 8.9, 4.8 Hz, 1 H), 4.07 (dd,
J = 9.3, 5.4 Hz, 1 H), 2.86–2.75 (m, 4 H), 2.34–2.23 (m, 1
H), 2.16–2.06 (m, 2 H), 1.94–1.84 (m, 1 H), 0.85 (s, 9 H),
0.06 (s, 3 H), –0.11 (s, 3 H) ppm. 13C NMR (75 MHz,
CDC13): d = 156.1, 141.6, 110.0, 106.3, 64.8, 43.4, 42.2,
30.1, 29.6, 26.0, 25.8, 18.2, –5.0, –5.2 ppm. ESI-MS: m/z =
367 [M + Na+]. The ee determination by derivatization
unfortunately resulted in elimination giving 19.
solution (50 mL), H2O (50 mL) and brine (50 mL). The
organic layer was dried (MgSO4) and concentrated to
approx. 60 mL. The so-prepared solution was used without
further purification, but stored in the fridge over 4 Å MS
(0.14 M); [a]D20 +36.7 (c 4.01, Et2O). 1H NMR (300 MHz,
CDC13): d = 7.79–7.75 (m, 2 H), 7.35–7.31 (m, 3 H), 6.32–
6.30 (m, 2 H), 4.95 (dd, 1 H, J = 4.4, 7.0 Hz), 4.31–4.19 (m,
2 H), 2.65 (br s, OH), 2.44 (s, 3 H), ppm. 13C NMR (75 MHz,
CDC13): d = 151.4, 145.1, 142.6, 132.5, 129.9, 128.0, 110.4,
107.9, 71.4, 65.9, 21.6 ppm. MS (ESI): m/z = 305 [M + N]+.
HRMS: m/z calcd for C13H14NaO5S: 305.0460; found:
305.0467. Note: Tosylate 6 is stable in solution and on silica
gel, however, if concentrated at elevated temperatures (40–
50 °C) rapid polymerization occurs affording a dark-green
gum. Analytical samples were obtained after column
chromatography, concentration at 20 °C and finally
evaporation of the remaining solvent under high vacuum.
Compound 6 is stable under argon for several hours in pure
form.
Compound 9: 1H NMR (300 MHz, CDC13): d = 7.36–7.34
(m, 1 H), 6.32–6.30 (m, 1 H), 6.24–6.22 (m, 1 H), 4.45 (d,
J = 6.5 Hz, 1 H), 4.03 (dd, J = 9.9, 6.5 Hz, 1 H), 3.90 (dd,
J = 9.9, 6.5 Hz, 1 H), 3.29 (td, J = 6.5, 6.5 Hz, 1 H), 2.88–
2.82 (m, 4 H), 0.85 (s, 9 H), 0.02 (s, 3 H), –0.01 (s, 3 H) ppm.
13C NMR (75 MHz, CDC13): d = 152.6, 141.3, 110.2, 108.1,
62.3, 48.6, 46.8, 30.7, 30.5, 29.7, 25.8, 18.2, –5.5 ppm. ESI-
MS: m/z = 367 [M + Na+].
(8) For other 2-furyloxirane precursors, such as 2-chlorofuryl
alcohols, sensitivity towards amines has been reported,3a,9
whereas tosylate 6 is stable in the presence of benzylamine
and even thioethane at r.t. as observed over 96 h.
(9) Tannis, S. P.; Evans, B. R.; Nieman, J. A.; Parker, T. T.;
Taylor, W. D.; Heasley, S. E.; Herrinton, P. M.; Perrault, W.
R.; Hohler, R. A.; Dolak, L. A.; Hester, M. R.; Seest, E. P.
Tetrahedron: Asymmetry 2006, 17, 2154.
NMR Data of Selected Compounds
(10) Peracetylation with Ac2O/pyridine, formation of the L-
glucosyl bromide with HBr/AcOH followed by elimination
with zinc dust achieved 53% overall yield. Following the
procedure for L-galactal: (a) Litjens, R. E. J. N.; den Heeten,
R.; Timmer, M. S. M.; Overkleeft, H. S.; van der Marel, G.
A. Chem. Eur. J. 2005, 11, 1010. (b) Tri-O-acetyl-L-glucal:
[a]D20 +23.4 (c 1.01, CHCl3). 1H NMR (300 MHz, CDC13):
d = 6.45 (d, 1 H, J = 6.1 Hz), 5.34–5.30 (m, 1 H), 5.20 (t, 1
H, J = 6.5 Hz), 4.83 (dd, 1 H, J = 6.2, 3.2 Hz), 4.38 (dd, 1 H,
J = 11.7, 6.2 Hz), 4.26–4.15 (m, 2 H), 2.08 (s, 3 H), 2.06 (s,
3 H), 2.03 (s, 3 H) ppm. 13C NMR (75 MHz, CDC13):
d = 170.4, 170.2, 169.4, 145.5, 98.9, 73.8, 67.3, 67.1, 53.3,
20.8, 20.6, 20.6 ppm.
(11) (a) Alcaide, B.; Areces, P.; Borredon, E.; Biurrun, C.;
Castells, J. P.; Plumet, J. Heterocycles 1990, 31, 1997.
(b) Oh, K. B.; Cha, J. H.; Cho, Y. S.; Choi, K. I.; Koh, H. Y.;
Chang, M. H.; Pae, A. N. Tetrahedron Lett. 2003, 44, 2911.
(12) (a) Alcaide, B.; Biurrun, C.; Plumet, J. Tetrahedron 1992,
48, 9719. (b) Sutowardoyo, K. I.; Emziane, M.; Lhoste, P.;
Sinou, D. Tetrahedron 1991, 47, 1435.
Compound 10: [a]D20 +15.5 (c 4.02, CHCl3). 1H NMR (400
MHz, CDC13): d = 7.37–7.35 (m, 1 H), 6.32–6.30 (m, 1 H),
6.26–6.24 (m, 1 H), 5.01 (dd, J = 8.9, 4.6, 1 H), 4.17 (dd,
J = 8.8, 5.8 Hz, 1 H), 2.91–2.78 (m, 4 H), 2.36–2.20 (m, 2
H), 2.15–2.05 (m, 2 H), 1.95–1.80 (m, 2 H) ppm. 13C NMR
(100 MHz, CDC13): d = 155.5, 142.3, 110.2, 106.3, 64.7,
43.3, 40.8, 29.9, 29.7, 25.9 ppm. ESI-MS: m/z = 253 [M +
Na+].
Compound 13: [a]D20 –19.8 (c 0.5, CHCl3). 1H NMR (300
MHz, CDC13): d = 7.33–7.32 (m, 1 H), 6.30–6.28 (m, 1 H),
6.09–6.07 (m, 1 H), 3.72 (br d, J = 6.2 Hz, 2 H), 2.87 (app
quin, J = 5.4 Hz, 1 H), 1.65–1.57 (m, 2 H), 1.53 (br s, OH),
1.34–1.19 (m, 4 H), 0.85 (t, J = 7.0 Hz, 3 H) ppm. 13C NMR
(75 MHz, CDC13): d = 156.3, 141.4, 110.0, 106.2, 65.2,
42.1, 29.7, 29.4, 22.6, 13.9 ppm.
Compound 18: 1H NMR (300 MHz, CDC13): d = 7.37–7.36
(m, 1 H), 6.33–6.31 (m, 1 H), 6.24–6.22 (m, 1 H), 4.07–4.02
(m, 1 H), 4.00–3.91 (m, 1 H), 3.88–3.80 (m, 1 H), 2.56–2.44
(m, 2 H), 1.20 (t, J = 7.4 Hz, 3 H) ppm. 13C NMR (125 MHz,
CDC13): d = 152.8, 142.3, 110.4, 107.4, 63.0, 45.6, 24.7,
14.8 ppm.
(13) Smith, A. B. III; Xian, M. J. Am. Chem. Soc. 2006, 128, 66.
(14) Representative Experimental Procedure and
Characterization Data for Selected Compounds
(15) The product from this reaction has been previously
characterized; our data agree with the previously published:
Blake, A. J.; Cunningham, A.; Ford, A.; Teat, S. J.;
Woodward, S. Chem. Eur. J. 2000, 6, 3586.
To a solution of 6 (5.0 mL, 0.71 mmol, 0.14 M) in Et2O7 was
added NaH (2 equiv, 60 mg, 60% in mineral oil) under an
Synlett 2007, No. 10, 1619–1621 © Thieme Stuttgart · New York