Reaction #12015

Reaction equation

sodium bicarbonate

(4R,9aR)-6-bromo-4-methyl-3,4,9,9a-tetrahydro-1H-2,4a,5-triaza-fluorene-2-carboxylic acid tert-butyl ester

intermediate b

(4R,9aR)-6-bromo-4-methyl-3,4,9,9a-tetrahydro-1H-2,4a,5-triaza-fluorene-2-carboxylic acid tert-butyl ester

ethyl acrylate

sodium acetate

tri(o-tolyl)phosphine

→

desired compound

Yield 91.2%

(4R,9aR)-6-(2-Ethoxycarbonyl-vinyl)-4-methyl-3,4,9,9a-tetrahydro-1H-2,4a,5-triaza-fluorene-2-carboxylic acid tert-butyl ester

Yield 91.2%

Solvents

toluene

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was heated
2. 2
   Temperatureunder reflux for 20 h
3. 3
   Extractionextracted with ethyl acetate
4. 4
   WashThe organic phase was washed with 10% aqueous citric acid solution and brine
5. 5
   Dryingdried over magnesium sulfate
6. 6
   Filtrationfiltered
7. 7
   Otherevaporated
8. 8
   OtherThe crude product was purified by column chromatography on silica gel (0.032–0.063 mm) with n-hexane:ethyl acetate (9:1) as eluant

Procedure

To a solution of 1.0 g (2.71 mmol) (4R,9aR)-6-bromo-4-methyl-3,4,9,9a-tetrahydro-1H-2,4a,5-triaza-fluorene-2-carboxylic acid tert-butyl ester (Example 5, intermediate b) and 0.36 ml (3.25 mmol) ethyl acrylate in 30 ml toluene were added 0.67 g (8.15 mmol) sodium acetate, 82.6 mg (0.27 mmol) tri(o-tolyl)phosphine and 0.04 mg (0.1 mmol) allylpalladium chloride dimer. The reaction mixture was heated under reflux for 20 h, then poured into saturated aqueous sodium bicarbonate solution and extracted with ethyl acetate. The organic phase was washed with 10% aqueous citric acid solution and brine, dried over magnesium sulfate, filtered and evaporated. The crude product was purified by column chromatography on silica gel (0.032–0.063 mm) with n-hexane:ethyl acetate (9:1) as eluant to afford the desired compound as a yellow solid (91.2%).

Source