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

Participants

Reaction Steps

To a solution of 2.0 g (5.43 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 50 ml 1,2-dimethoxyethane 0.75 g (0.65 mmol) tetrakis(triphenylphosphine)palladium was added. After 20 min, 16.3 ml (16.3 mmol) triisobutylaluminium (1M solution in n-hexane) was added and the reaction mixture was heated under reflux for 66 h. After cooling to room temperature another 8.1 ml (8.1 mmol) triisobutylaluminium (1M solution in n-hexane) was added and the reaction again heated under reflux. After 5 h the reaction was poured onto 1M aqueous sodium hydroxide solution and extracted three times with ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulfate, filtered and evaporated. The residue was chromatographed on silica gel (0.032–0.063 mm) with ethyl acetate:n-hexane (1:3) as eluant to afford the desired compound as a light brown oil (76.2%).

Provenance & Evidence