Reaktion #635474

Reaktionsgleichung

Quinine

cis-5-Norbornene-endo-2,3-dicarboxylic anhydride

toluene

methanol

→

(1R,2S,3R,4S)-3-(methoxycarbonyl)bicyclo[2.2.1]hept-5-ene-2-carboxylic acid

Ausbeute 98.0%

Lösungsmittel

carbon tetrachloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe flask was degassed
2. 2
   workup.STIRRINGWhile stirring
3. 3
   workup.STIRRINGThe mixture was stirred at −55° C. for 20 h
4. 4
   TemperaturUpon warming to 25° C.
5. 5
   Einengenthe mixture was concentrated in vacuo to a thick oil
6. 6
   workup.DISSOLUTIONThe oil was dissolved in ethyl acetate (400 mL)
7. 7
   Waschenwashed with 1.0 M aqueous hydrochloric acid solution (2×400 mL), saturated aqueous brine solution (100 mL)
8. 8
   Trocknendried over magnesium sulfate
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated in vacuo

Vorschrift

The starting material (a) was prepared as described in J. Org. Chem. 2000, 65, 6984-6991. cis-5-Norbornene-endo-2,3-dicarboxylic anhydride (4.104 g, 25 mmol) was suspended in a 1:1 mixture of toluene and carbon tetrachloride (500 mL). The mixture was stirred for 20 min. Quinine (8.92 g, 27.5 mmol) was added and the flask was degassed and backfilled with nitrogen. The solution was cooled to −55° C. While stirring, methanol (3.04 mL, 75 mmol) was added. The mixture was stirred at −55° C. for 20 h. Upon warming to 25° C., the mixture was concentrated in vacuo to a thick oil. The oil was dissolved in ethyl acetate (400 mL), washed with 1.0 M aqueous hydrochloric acid solution (2×400 mL), saturated aqueous brine solution (100 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford the desired product, (1R,2S,3R,4S)-3-(methoxycarbonyl)bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (4.8 g, 24.5 mmol, 98%), as a clear waxy solid. 1H NMR (400 MHz, DMSO-d6) δ: 1.26 (1H, d, J=8.5 Hz), 1.33 (1H, d, J=8.8 Hz), 3.00 (1H, s), 3.03 (1H, s), 3.21-3.30 (2H, m), 3.45 (3H, s), 6.02-6.04 (1H, m), 6.14-6.16 (1H, m), 11.86 (1H, s).

Quelle