反应详情

A mixture of 3-(4-benzyloxy-phenyl)-2-hydroxy-propionic acid (2.0 g, 7.34 mmol), 2,2-dimethoxypropane (18.63 g, 179 mmol) and pyridinium p-toluene sulfonate (0.92 g, 3.66 mmol) in CHCl3 (80 mL) was heated to reflux for 40 minutes under N2. The reaction was cooled and worked up extractively with CH2Cl2 and water. The organic layer was dried (Na2SO4) and the solvent removed in vacuo to afford crude product that was purified by flash chromatography using 10:1 hexanes:acetone to afford 2.01 g (88%) 5-(4-benzyloxy-benzyl)-2,2-dimethyl-[1,3]dioxolan-4-one. Rf=0.53 (1:1 hexanes:acetone). 1H NMR (500 MHz, CDCl3) δ 7.43-7.35 (m, 4H), 7.34-7.29 (m, 1H), 7.16 (d, 2H, J=8.80 Hz), 6.91 (d, 2H, J=8.80 Hz), 5.04 (s, 2H), 4.61 (dd, 1H, J=6.36 Hz, J=4.40 Hz), 3.13 (dd, 1H, J=14.67 Hz, J=4.40 Hz), 2.99 (dd, 1H, J=14.67 Hz, J=4.40 Hz), 1.50 (s, 3H), 1.36 (s, 3H); MS (ES+) Calc'd for C19H20O4 (M+NH4) 330. Found m/z 330 (100%).

1. temperaturewas heated
2. temperatureto reflux for 40 minutes under N2
3. temperatureThe reaction was cooled
4. dry with materialThe organic layer was dried (Na2SO4)
5. customthe solvent removed in vacuo
6. customto afford crude product that
7. customwas purified by flash chromatography