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Procedure: 250 mL
1-neck flask, stirbar, septum, N2 inlet Dissolved
3.157 g of lactate I in 40 mL of neat
isobutanol. Stirred at rt. Added 0.050 g of NaH (60% disp. in
mineral oil). After 16 h, TLC
shows product spot at Rf 0.70 (1:9 EtOAc-hexanes, I2). The reaction mixture was poured into
1.0 M HCl and extracted with EtOAc.
The organic layer was dried over MgSO4, filtered and the
solvent was removed by rotary evaporation. The product was isolated by flash chromatography on silica
gel using 1:19 EtOAc-hexanes as eluant.
The product was a clear, colorless oil. 1H NMR (CDCl3,
300 MHz) d 4.32 (q, J = 6.7 Hz, H2, 1H), 3.90 (m, 2H, CO2CH2),
1.95 (septet, J = 6.6 Hz, CH(CH3)2,
1H), 1.40 (d, J = 6.6 Hz, H3,
3H), 0.93 (d, J = 6.6 Hz, CH(CH3)2,
6H), 0.90 (s, Si(CH3)3, 9H), 0.09 (s, Si(CH3)2,
3H), 0.06 (s, Si(CH3)2, 3H). notes This reaction is actually
catalytic in NaH. The initial
addition of sodium hydride forms the alkoxide of isobutanol. The isobutoxide then displaces
methoxide to give the desired ester and NaOMe. NaOMe is basic enough to react with additional isobutanol to
generate more isobutoxide and drive the whole process. | |||||||||||||||||||||||||||||||||||||||
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