Réaction #511366

Équation de réaction

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

Rendement 98.0%

Solvants

carbon tetrachloride

Conditions de réaction

Traitement

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

Mode opératoire

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).

Source