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%).
