 | ||
 | | |
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
Procedure: 10 mL
1-neck flask, stirbar, septum, N2 inlet Dissolved
0.050 g of I in 3.0 mL of dry CH2Cl2. Stirred at rt and added 0.0015 g of
VO(acac)2. The mixture
was cooled to 0 C and 0.031 mL of IV was added. A red color
was obtained. After 4 h, the
solution had become almost colorless.
TLC (10:90 EtOAc-hexanes, PMA) showed product spot at Rf 0.25 along with
starting material at Rf 0.40.
Added another 0.0023 g of VO(acac)2 and 0.031 mL of IV and, again, obtained a red solution. After an additional 4.5 h, the reaction
mixture is almost colorless, however, TLC still shows unreacted sm. Added another 0.0025 g of VO(acac)2. After 3 h, the reaction is again
colorless. Added another 0.0029 g
of VO(acac)2 and then added a spatula full of VO(acac)2. The reaction mixture was stirred
overnight as the bath warmed to rt.
The solvent was removed by rotary evaporation and the product was
isolated by flash chromatography on silica gel using 10:90 EtOAc-hexanes as
eluant. The product was a
clear, colorless oil. Unreacted
starting material was also obtained.
1H NMR (CDCl3,
400 MHz) d 5.68 (dq, J = 15.4, 6.4 Hz, H7), 5.45 (ddq, J = 15.4, 7.4, 1.5 Hz, H6), 4.13 (dd, J = 7.2, 4.9 Hz, H5), 3.80 (dd, J = 11.9, 4.4 Hz, H1), 3.76 (dd, J = 11.9, 5.9 Hz, H1), 3.40 (m, H4), 3.11 (m, H2),
3.05 (dd, J = 6.3, 4.4 Hz, H3),
2.44 (d, J = 6.4, 1.3 Hz, OH),
1.70 (dd, J = 6.4, 1.3 Hz, H8),
0.89 (s, SiC(CH3)3), 0.88 (s, SiC(CH3)3),
0.07 (s, SiCH3), 0.06 (s, SiCH3), 0.06 (s, SiCH3),
0.02 (s, SiCH3). | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||||||||||
| | | | | | | ||||||||||||||||||||||||||||||||||||||||