Journal of Sulfur Chemistry 615
Carbo-desilylation. Two 5 mL round bottom flasks equipped with a magnetic stirring bar were
separately charged with 0.5 mmol of the two diastereoisomers 11c and 11ꢀc under N2 atmosphere.
Dry THF (1 mL for each flask) was then added followed by 1.0 mmol of 2-furaldehyde. Dry
TBAF 0.5 M in dry THF (aliquots of 0.1 mmol) was added at r.t. in each flask to the homogenized
solutions. After the addition of only 0.2 eq. of TBAF, 11c and 11ꢀc were not detectable (TLC
eluent petroleum ether/Et2O: 4/1), nevertheless the addition of 1.0 eq. of TBAF was completed
in order to avoid the presence of O-SiMe3 derivatives along with alcohols 14c and 15c. After an
hour of stirring at r.t., the reactions were quenched by the addition 0.5 mL of a saturated solution
of NH4Cl. After extraction with Et2O and evaporation of solvents, the residues were separately
purified by flash chromatography on silica gel.A first fraction containing the two diastereoisomers
of 14c in a 1:1 ratio (1H-NMR) was obtained using petroleum ether/Et2O:4/1 as the eluent, next
a second fraction containing the two diastereomers of 15c in a 1:1 ratio (1H-NMR) was obtained
using petroleum ether/Et2O:7/3 as the eluent. From11c (0.207 g of crude product), it was obtained
a first fraction (0.0633 g) of 14c/14ꢀc and a second fraction (0.0761 g) of 15c/15ꢀc; from 11ꢀc
(0.223 g of crude product), it was obtained a first fraction (0.0617 g) of 14c/14ꢀc and a second
fraction (0.0760 g) of 15c/15ꢀc.
1
14c/14ꢀc. Mixture of isomers. H NMR (400 MHz, CDCl3) δ (ppm): 1.33 (d, 3H, J = 6 Hz),
1.35 (d, 3H, J = 6 Hz), 2.58–2.82 (bs, 2H), 3.52 (app t, 2H), 3.91–4.03 (m, 2H), 4.07–4.15
(m, 2H), 4.87 (s, 1H), 4.88 (s, 1H), 6.17 (dd, 2H, J = 7 Hz, J = 1 Hz), 6.27 (bs, 2H), 7.32 (bs,
2H), 7.48–7.54 (m, 8H). 13C NMR (75.45 MHz, CDCl3): δ = 17.9, 18.0, 71.7, 72.0, 72.5, 72.6,
72.8, 73.0, 108.9, 109.2, 109.5, 109.6, 110.4, 124.7 (q, JC−F = 285 Hz), 124.77, 124.82, 124.86,
127.0, 127.1, 142.0, 142.1, 144.0, 151.5, 151.5.
15c/15ꢀc. Mixture of isomers. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.18 (d, 3H, J = 6 Hz), 1.20
(d, 3H, J = 6 Hz), 2.42–2.58 (bs, 2H), 3.33 (dd, 2H, J = 15, 7 Hz), 4.23 (dd, 1H, J = 15, 4 Hz),
4.24 (dd, 1H, J = 15, 4 Hz), 4.32–4.41 (m, 2H), 4.83 (s, 1H), 4.87 (s, 1H), 6.14 (bd, 2H, J = 1 Hz),
6.26–6.28 (m, 2H), 7.32 (bd, 2H, J = 6 Hz), 7.42–7.55 (m, 8H). 13C NMR (75.45 MHz, CDCl3):
δ = 18.3, 18.4, 71.6, 71.9, 72.9, 74.8, 75.1, 108.9, 109.0, 110.4, 124.6 (q, JC−F = 284 Hz), 124.7,
124.76, 126.89, 126.98, 142.1, 142.2, 144.5, 151.5. MS (m/z): 328 (0.08) [M+]; 254 (3); 331
(88); 225 (6); 173 (100); 145 (20); 95 (8).
Acknowledgements
The authors gratefully acknowledge Professor Alfredo Ricci, University of Bologna, for helpful discussion and scientific
contribution. Financial support from MiUR, National Project PRIN 2007, is gratefully acknowledged.
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