226
M. J. Are´6alo et al. / Tetrahedron: Asymmetry 13 (2002) 223–226
6. In other and recent works, the mesoionic dipole is fused
H-5%%), 3.51 (dd, 1H, J=3.9, 8.1 Hz, H-5), 2.85 (N-CH3),
2.80 (m, 2H, H-6exo and H-6endo), 2.25 (s, 3H, OAc), 2.18
(s, 3H, OAc), 2.15 (s, 3H, OAc), 2.09 (s, 3H, OAc); 13C
NMR (CDCl3) l 172.7, 170.6, 169.8, 169.7, 169.6, 130.8,
129.4, 128.8, 128.2, 118.2, 78.8, 70.2, 69.2, 67.4, 67.0,
61.4, 42.4, 37.9, 28.0, 21.0, 20.8, 20.7, 20.2. Anal. calcd
for C28H32N2O11S: C, 55.62; H, 5.33; N, 4.63; S, 5.30.
Found: C, 55.33; H, 5.43; N, 4.77; S, 5.22%.
to either, cyclic sugars or heterocycles: (a) Yokohama,
A.; Ikuma, T.; Obara, N.; Togo, H. J. Chem. Soc., Perkin
Trans. 1 1990, 3243–3247; (b) Areces, P.; Avalos, M.;
Babiano, R.; Gonza´lez, L.; Jime´nez, J. L.; Palacios, J. C.;
Pilo, M. D. Carbohydr. Res. 1991, 222, 99–112; (c) Are-
ces, P.; Avalos, M.; Babiano, R.; Gonza´lez, L.; Jime´nez,
J. L.; Me´ndez, M. M.; Palacios, J. C. Tetrahedron Lett.
1993, 34, 2999–3002; (d) Gaiser, F.; Granier, T.; Hinter-
mann, L.; Vasella, A. Helv. Chim. Acta 1997, 80, 1443–
1456; (e) Are´valo, M. J.; Avalos, M.; Babiano, R.;
Cintas, P.; Hursthouse, M. B.; Jime´nez J. L.; Light, M.
E.; Lo´pez, I.; Palacios, J. C. Tetrahedron Lett. 1999, 40,
8675–8678; (f) Wamhoff, H.; Ho¨hmann, Ch.; Soha´r P.
Org. Lett. 2000, 2, 581–584; (g) Are´valo, M. J.; Avalos,
M. J.; Babiano, R.; Cintas, P.; Hursthouse, M. B.;
Jime´nez, J. L.; Light, M. E.; Lo´pez, I.; Palacios, J. C.
Tetrahedron 2000, 56, 1247–1255.
10. This fact was somewhat surprising because previous
results have revealed that [3+2] cycloadditions based on
mesoionics proceed with a high level of facial diastereose-
lectivity (see Refs. 4b–d and 4g–i). An explanation of this
abnormal behavior will be the subject of a further theo-
retical analysis.
11. Compound 8a: orthorhombic, space group P212121, a=
,
10.9877(7), b=11.9703(8), c=22.4663(18) A, V=
3
2954.9(4) A , Z=2, dcalcd=1.359 Mg/m3, q range for data
,
collection=3.10–25.02°, index ranges=−125h511,
−145k511, −265l526, (Mo K)=0.172 mm−1. For a
total of 13093 collected reflections, 5105 were indepen-
dent reflections [Rint=0.2525]. The final R indices were
R1=0.0848, wR2=0.1318 [F2>2|(F2)], R1=0.3088,
wR2=0.1930 (all data). A final difference map displayed
7. Are´valo, M. J.; Avalos, M.; Babiano, R.; Cabanillas, A.;
Cintas, P.; Jime´nez, J. L.; Palacios, J. C. Tetrahedron:
Asymmetry 2000, 11, 1985–1995.
8. Compound 4: yield 63%; mp 65–70°C; [h]D +128, [h]578
+140, [h]546 +167 (c 0.5, chloroform); 1H NMR
(CDCl3) l 7.90–7.16 (m, 5H, phenyl), 6.30 (d, 1H, J=6.3
Hz, H-1%), 5.69 (dd, 1H, J=4.3, 6.3 Hz, H-2%), 5.34 (dd,
1H, J=4.3, 6.6 Hz, H-3%), 5.02 (m, 1H, H-4%), 4.38 (dd,
1H, J=2.5, 12.7 Hz, H-5%), 4.09 (dd, 1H, J=5.6, 12.7 Hz,
H-5%%), 3.81 (N-CH3), 2.18 (s, 3H, OAc), 2.15 (s, 3H,
OAc), 2.10 (s, 3H, OAc), 2.09 (s, 3H, OAc), 2.05 (s, 3H,
OAc); 13C NMR (CDCl3) l 170.7, 169.7, 169.5, 169.3,
169.0, 159.8, 143.6, 132.6, 128.6, 125.7, 124.1, 99.9, 68.9,
68.5, 68.2, 67.1, 61.4, 33.1, 20.6, 20.5, 20.3, 20.2.
9. Typical [3+2] cycloaddition procedure. A solution of 4
(1.0 g, 1.81 mmol) and acrylonitrile (0.14 mL, 2.17 mmol)
in dry dichloromethane (15 mL) was heated under reflux
for 5 h. The solvent was then evaporated under reduced
pressure and the residue subjected to flash chromatogra-
phy (silica gel, diethyl ether). The resulting oil was further
purified by preparative chromatography on silica gel
(diethyl ether) to give 8a and 8b.
the highest electron density of −0.366 e A−3. Crystallo-
,
graphic data have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publica-
tion no. CCDC-14652. Copies of the data can be
obtained free of charge from the Director, Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK.
12. Potts, K. T.; Baum, J.; Houghton, E. J. Org. Chem. 1974,
25, 3631–3641.
13. Hydrogen sulfide elimination procedure. The latter
cycloadducts, either 8a (0.16 mmol, 0.1 g) or 8b (0.16
mmol, 0.1 g) were poured into a stirred solution of
mercury(II) acetate (0.32 mmol, 0.10 g) in acetic acid (6
mL) and the mixture was stirred at room temperature.
Acetone (6 mL) was added to the resulting suspension
and stirring was continued for 3 h. The reaction mixture
was filtered and diluted with water (6 mL). After adjust-
ing the pH to ꢀ5 with sodium hydrogen carbonate, the
mother liquors were extracted with chloroform (3×6 mL).
The organic layers were washed with a 1 M solution of
sodium hydrogen carbonate followed by distilled water,
then dried over anhydrous magnesium sulfate and con-
centrated. The residue was purified by preparative chro-
matography on silica gel (diethyl ether) to give 12 as a
white amorphous solid: 40% yield; mp 85–87°C; [h]D
+114, [h]578 +123, [h]546 +147 (c 0.5, chloroform); 1H
NMR (CDCl3) l 7.55–7.44 (m, 5H, phenyl), 6.34 (s, 1H,
H-5), 6.06 (d, 1H, J=4.0 Hz, H-1%), 5.57 (t, 1H, J=5.0
Hz, H-2%), 5.45 (t, 1H, J=5.0 Hz, H-3%), 5.06 (m, 1H,
H-4%), 4.38 (dd, 1H, J=2.8, 12.5 Hz, H-5%), 4.11 (dd, 1H,
J=5.9, 12.5 Hz, H-5%%), 3.76 (N-CH3), 2.23 (s, 3H, OAc),
2.14 (s, 3H, OAc), 2.08 (s, 3H, OAc), 2.06 (s, 3H, OAc);
13C NMR (CDCl3) l 170.7, 169.8, 169.5, 160.9, 144.3,
137.3, 132.6, 129.6, 128.3, 119.2, 116.1, 105.7, 69.6, 69.2,
69.0, 68.2, 61.5, 32.1, 20.6, 20.2. Anal. calcd for
C28H30N2O11: C, 58.94; H, 5.30; N, 4.91. Found: C,
58.93; H, 5.27; N, 5.0%.
Compound 8a: mp 95–98°C (dec.); [h]D +6, [h]578 +6,
[h]546 +6.5 (c 0.5, chloroform); 1H NMR (CDCl3) l
7.47–7.43 (m, 5H, phenyl), 5.77 (d, 1H, J=5.4 Hz, H-1%),
5.60 (t, 1H, J=4.7 Hz, H-2%), 5.44 (dd, 1H, J=4.6, 6.5
Hz, H-3%), 5.13 (m, 1H, H-4%), 4.39 (dd, 1H, J=3.0, 12.6
Hz, H-5%), 4.17 (dd, 1H, J=5.1, 12.6 Hz, H-5%%), 3.56 (dd,
1H, J=3.6, 8.0 Hz, H-5), 2.85 (m, 2H, H-6exo and
N-CH3), 2.74 (dd, 1H, J=3.6, 12.7 H-6endo), 2.22 (s, 3H,
OAc), 2.18 (s, 3H, OAc), 2.14 (s, 3H, OAc), 2.11 (s, 3H,
OAc), 2.09 (s, 3H, OAc); 13C NMR (CDCl3) l 173.1,
171.1, 170.7, 170.5, 169.8, 169.3, 130.7, 129.4, 128.8,
128.3, 118.3, 80.1, 69.9, 69.4, 69.1, 67.9, 66.8, 61.7, 42.4,
39.1, 28.5, 20.7, 20.6, 20.5, 20.5. Anal. calcd for
C28H32N2O11S: C, 55.62; H, 5.33; N, 4.63; S, 5.30.
Found: C, 55.31; H, 5.28; N, 4.64; S, 5.48%.
Compound 8b: mp 90–95°C (dec.); [h]D +67.5, [h]578
+71.5, [h]546 +82 (c 0.5, chloroform); 1H NMR
(CDCl3) l 7.48–7.43 (m, 5H, phenyl), 5.82 (d, 1H, J=4.1
Hz, H-1%), 5.46 (t, 1H, J=4.1 Hz, H-2%), 5.41 (dd, 1H,
J=4.1, 6.3 Hz, H-3%), 5.14 (m, 1H, H-4%), 4.38 (dd, 1H,
J=2.9, 12.5 Hz, H-5%), 4.19 (dd, 1H, J=5.6, 12.5 Hz,