1
824
A. Boto et al. / Tetrahedron Letters 43 (2002) 1821–1824
+
Lett. 1997, 38, 4141–4144. The purification of the acid
307 (M −Me, 5), 217 (3), 105 (100), 77 (13). Anal. calcd
precursors was difficult in some cases. In contrast, our
substrates are readily synthesized and easily purified.
for C H O : C, 59.62; H, 5.63. Found: C, 59.54; H,
16
18
7
−
1
1
5.42%. Compound 6b: IR 1735, 1602, 1585 cm ;
H
1
1
0. For the sake of clarity, the aldose numbering is retained
in the obtained products.
1. (a) Majetich, G.; Wheless, K. Tetrahedron 1995, 51,
NMR (500 MHz) 1.36 (3H, s), 1.53 (3H, s), 1.98 (3H, s),
4.87 (1H, d, J=5.7 Hz), 4.94 (1H, d, J=5.7 Hz), 6.37
(1H, s), 6.56 (1H, s), 7.46 (2H, dd, J=7.9, 7.8 Hz), 7.60
(1H, dd, J=7.5, 7.4 Hz), 8.04 (2H, d, J=8.4 Hz); MS
7
095–7129 and references cited therein; (b) Francisco, C.
G.; Herrera, A. J.; Su a´ rez, E. Tetrahedron Lett. 2000, 41,
869–7873.
2. Boto, A.; Hern a´ ndez, R.; Su a´ rez, E. Tetrahedron Lett.
001, 42, 9167–9170 and references cited therein.
+
(EI) m/z (rel. intensity) 307 (M −Me, 42), 105 (100), 77
7
(72). Anal. calcd for C H O : C, 59.62; H, 5.63. Found:
16
18
7
1
1
C, 59.76; H, 5.44%. Compound 7: IR 1732, 1602, 1585
−
1 1
2
cm ; H NMR (500 MHz) 1.37 (3H, s), 1.51 (3H, s), 5.04
(1H, d, J=5.6 Hz), 5.14 (1H, d, J=5.6 Hz), 6.15 (1H, s),
6.60 (1H, s), 7.46 (2H, dd, J=7.9, 7.7 Hz), 7.60 (1H, dd,
J=7.5, 7.3 Hz), 8.08 (2H, d, J=7.3 Hz); MS (EI) m/z
3. (a) Bishop, R. In Comprehensive Organic Synthesis;
Trost, B. M.; Fleming, I., Eds.; Pergamon Press: Oxford,
1
991; Vol. 6, pp. 261–300; (b) Kita, Y.; Shibata, N.;
+
Kawano, N.; Yoshida, N.; Matsumoto, K.; Takebe, Y. J.
Chem. Soc., Perkin Trans. 1 1996, 2321–2329.
(rel. intensity) 285/283 (M −Me, 3.29/10.46), 105 (100).
Anal. calcd for C14
H15ClO : C, 56.29; H, 5.06. Found: C,
5
1
14. All new compounds were fully characterised by H and
56.35; H, 5.12%. Compound 8: IR 3066, 1725, 1643,
1
3
−1 1
C NMR, IR, MS, HRMS and elemental analysis. The
1602, 1584 cm ; H NMR (500 MHz) 1.35 (3H, s), 1.53
(3H, s), 2.34 (1H, ddd, J=15.4, 8.0, 7.7 Hz), 2.48 (1H,
ddd, J=14.1, 7.2, 6.4 Hz), 4.41 (1H, dd, J=7.8, 7.8 Hz),
4.70 (1H, d, J=5.8 Hz), 4.90 (1H, d, J=5.9 Hz), 5.07
(1H, dd, J=17.0, 1.5 Hz), 5.09 (1H, dd, J=9.1, 1.4 Hz),
5.79 (1H, dddd, J=17.1, 10.4, 7.0, 6.6 Hz), 6.45 (1H, s),
7.45 (2H, dd, J=7.9, 7.7 Hz), 7.58 (1H, dd, J=7.4, 7.4
1
stereochemistry was assigned by H and 2D COSY–
NOESY NMR. Selected spectroscopic data (IR,
1
H
NMR, MS and elemental analysis) for compounds 6–8
are given. Compound 6a: amorphous; IR 1733, 1602,
−
1 1
1
585 cm ; H NMR (500 MHz) 1.40 (3H, s), 1.57 (3H,
s), 2.17 (3H, s), 4.86 (1H, d, J=5.8 Hz), 5.04 (1H, dd,
J=5.4, 4.5 Hz), 6.26 (1H, d, J=4.0 Hz), 6.49 (1H, s),
Hz), 8.01 (2H, d, J=7.1 Hz); MS (EI) m/z (rel. intensity)
+
7
.45 (2H, dd, J=7.9, 7.6 Hz), 7.60 (1H, dd, J=7.6, 7.3
289 (M −Me, 5), 105 (100). Anal. calcd for C17
H
20
O
: C,
5
Hz), 8.01 (2H, d, J=8.0 Hz); MS (EI) m/z (rel. intensity)
67.09; H, 6.62. Found: C, 66.89; H, 6.80%.