Reaktion #12019

Reaktionsgleichung

water

ethyl acetate

(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

triethylamine

→

product

Ausbeute 74.4%

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

Ausbeute 74.4%

Lösungsmittel

brine

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Extraktionwas extracted with further portions of ethyl acetate
2. 2
   SonstigeThe combined organic layers were separated
3. 3
   Trocknendried over magnesium sulfate
4. 4
   Filtrationfiltered
5. 5
   SonstigeThe residue was purified by chromatography on silica gel (0.032–0.063 mm)

Vorschrift

To a solution of 6.0 g (16.3 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) in 60 ml methanol were added 0.57 g (0.8 mmol) and 3.4 ml (2.5 g, 24.4 mmol) triethylamine and the reaction mixture was stirred at 80 deg C. for 24 h under a carbon monoxide atmosphere of 40 bar. The suspension was cooled to room temperature, poured into a mixture of water, ethyl acetate and brine and was extracted with further portions of ethyl acetate. The combined organic layers were separated, dried over magnesium sulfate and filtered. The residue was purified by chromatography on silica gel (0.032–0.063 mm) to afford the product as a light yellow foam (74.4%).

Quelle