反応 #2646

反応方程式

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

収率 45.0%

溶媒

tert-butyl methyl ether

反応条件

後処理

1. 1
   ろ過The reaction is then filtered through diatomaceous earth
2. 2
   濃縮the filtrate is concentrated under vacuum
3. 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-(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.

出典