Реакция #2646

Уравнение реакции

chloroform

(-)-cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol

chloroform

triethylamine

vinyl acetate

Cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol

→

(-)-acetic acid cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enyl ester

Выход 45.0%

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 (10% to 20% ethyl acetate/hexane)

Методика

Cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol (1.091 g, 5.92 mmol, prepared in example 6) is dissolved in tert-butyl methyl ether (8.6 mL, anhydrous). To the solution is added triethylamine (0.59 mL, 4.2 mmol), pancreatin (3.2 g, available from Sigma Chemical Company), and vinyl acetate (2.7 mL, 29 mmol). 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 (10% to 20% ethyl acetate/hexane) to provide (-)-acetic acid cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enyl ester (B, 601 mg, 45% yield, 91% ee) [α]D =-19.8°,(c=1.00, chloroform) as a yellow oil and (-)-cis-4-(tetrahydro-pyran-2-yloxy)-cyclopent-2-enol (A, 560 mg, 50% yield, 94% ee), [α]D =-9.9°, (c=1.06, chloroform) as a yellow oil.

Источник