Реакция #2651

Уравнение реакции

Cis-4-benzyloxy-cyclopent-2-enol

triethylamine

vinyl acetate

chloroform

chloroform

→

(-)-cis-4-benzyloxy-cyclopent-2-enol

Выход 29.0%

(-)-acetic acid cis-4-benzyloxy-cyclopent-2-enyl ester

Выход 70.0%

Растворители

tert-butyl methyl ether

Условия реакции

Обработка

1. 1
   ФильтрацияThe reaction is then filtered through diatomaceous earth
2. 2
   Концентрированиеthe filtrate is concentrated under vacuum
3. 3
   ДругоеThe products are separated by chromatography on silica gel (20% ethyl acetate/hexane)

Методика

Cis-4-benzyloxy-cyclopent-2-enol (500 mg, prepared in example 16) 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 7 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 (20% ethyl acetate/hexane) to provide (-)-cis-4-benzyloxy-cyclopent-2-enol (A) (147 mg, 29% yield) [α]20D -12°, (c=1.09, chloroform), and (-)-acetic acid cis-4-benzyloxy-cyclopent-2-enyl ester (B) (427 mg, 70% yield),[α]20D =-5.2°, (c=0.97, chloroform), 1 H NMR (CDCl3) δ 7.3 (m, 5H), 6.13 (d, 1H, J=5 Hz), 5.99 (d, 1H, J=5 Hz), 5.5 (m, 1H), 4.59 (d, 1H, J=11.8 Hz), 4.54 (d, 1H, J=11.8 Hz), 4.5 (m, 1H), 2.78 (d appt, 1H, J=7.2, 14.3 Hz), 2.05 (s, 3H), 1.76 (d appt, 1H, J=4.4, 14.3 Hz); 13C NMR (CDCl3) δ171.1, 138.5, 136.4, 133.1, 128.7, 128, 127.9, 81.4, 77.1, 71.2, 37.8, 21.4.

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