反応 #2649
ord-1ac771ea14f8470d9583f912bd68a7b3
反応方程式
反応条件
後処理
- 1ろ過The reaction is then filtered through diatomaceous earth
- 2濃縮the filtrate is concentrated under vacuum
- 3その他The products are separated by chromatography on silica gel (10% to 20% ethyl acetate/hexane)
実験手順
Cis-4-tert-butyloxy-cyclopent-2-enol (485 mg, 3.1 mmol, prepared in example 9) is dissolved in tert-butyl methyl ether (8.6 mL, anhydrous). To the solution is added triethylamine (0.7 eq), pancreatin (3 wt eq, available from Sigma Chemical Company), and vinyl acetate (5 eq). The reaction is allowed to stir for 17 hours at room temperature. The reaction is then filtered through diatomaceous earth and the filtrate is concentrated under vacuum. The products are separated by chromatography on silica gel (10% to 20% ethyl acetate/hexane) to provide (-)-acetic acid cis-4-tert-butyloxy-cyclopent-2-enyl ester (B, 50% yield, 76% ee), [α]D =-10.9°, (c=0.98, chloroform), 1H NMR (CDCl3) δ5.94 (d, 1H, J=5.5 Hz), 5.89 (d, 1H, J=5.5 Hz), 5.46 (appt, 1H, J=5.5 Hz), 4.52 (appt, 1H, J=5.5 Hz), 2.8 (m, 1H), 2.0 (s, 3H), 1.6 (d appt, 1H, J=4.8, 14 Hz), 1.22 (s, 9H); 13C NMR (CDCl3) δ171.2, 138.6, 131.6, 77.4, 77.2, 41, 28.7, 28.6, 21.4; IR (neat) νmax 2976, 1738, 1364, 1242, 1196, 1067, 1020 cm-1 ; CIMS m/e (% relative intensity) 199 (M+H+, 4), 139 (M+H+ -AcOH, 70), 83 (100), and (-)-cis-4-tert-butyloxy-cyclopent-2-enol (A, 194 mg, 40% yield, >98% ee), [α]D 17.2°, (c=1.09, chloroform) as a yellow oil.