[Cl:1][C:2]1[N:3]=[C:4]2[C:12](=[CH:13][C:14]=1[O:15][CH2:16][CH3:17])[CH:11]=[C:10]1[N:5]2[C@H:6]([CH3:19])[CH2:7][NH:8][C:9]1=O.[H-].[Al+3].[Li+].[H-].[H-].[H-].C(C(C(C([O-])=O)O)O)([O-])=O.[K+].[Na+]>COC(C)(C)C>[Cl:1][C:2]1[N:3]=[C:4]2[C:12](=[CH:13][C:14]=1[O:15][CH2:16][CH3:17])[CH:11]=[C:10]1[N:5]2[CH:6]([CH3:19])[CH2:7][NH:8][CH2:9]1A suspension consisting of 0.51 g (1.82 mmol) (R)-6-chloro-7-ethoxy-4-methyl-3,4-dihydro-2H-2,4a,5-triaza-fluoren-1-one and 0.28 g (7.30 mmol) lithium aluminium hydride in 10 mL tert-butyl methyl ether was heated at reflux for 1 h. After cooling to room temperature the reaction mixture was poured into 10% aqueous sodium potassium tartrate solution and extracted twice with ethyl acetate. The organic fractions were washed with brine, dried over magnesium sulfate, filtered and evaporated. The so-obtained crude 6-chloro-7-ethoxy-4-methyl-1,2,3,4-tetrahydro-2,4a,5-triaza-fluorene was dissolved in 10 mL dichloromethane and 0.48 g (2.19 mmol) di-tert-butyl dicarbonate and 22.3 mg (0.18 mmol) 4-(dimethylamino)pyridine were added. After 1 h the solvent was evaporated and the residue was purified by column chromatography over silica gel (0.030–0.063 mm) with ethyl acetate:n-hexane (1:4) as eluant to give the product as a light yellow solid (63.9%).
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