A mixture of 1-bromo-8-chloro-5-methyl-5,6-dihydro-4H-2,3,5,10b-tetraaza-benzoazulene (50 mg, 0.16 mmol), tetrabutylammonium bromide (10 mg, 0.031 mmol) and 3H-spiro[2-benzofuran-1,4′-piperidin]-3-one (65 mg, 0.32 mmol) in sulfolane (0.5 ml) was stirred for 20 h at 160° C. The reaction mixture was poured on water and extracted with tert-butyl methyl ether. The organic layer was washed with water, dried over anhydrous sodium sulfate and concentrated in vacuo. Residual sulfolane was evaporated by kugelrohrdistillation (120° C., 1-2 mbar). Preparative HPLC with n-heptane/2-propanol (70:30) as eluent gave the title compound (10 mg, 14%) as light yellow solid. MS m/e: 436 (M+H+).
