반응 #2649
ord-1ac771ea14f8470d9583f912bd68a7b3
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후처리
- 1여과The reaction is then filtered through diatomaceous earth
- 2농축the filtrate is concentrated under vacuum
- 3기타The products are separated by chromatography on silica gel (10% to 20% ethyl acetate/hexane)
실험 절차
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.