To a solution of diisopropylamine (1.01 g) in tetrahydrofuran (15 ml) at -70° C. under a nitrogen atmosphere was added 1.64M butyllithium in hexane (6.1 ml). After being stirred at the same temperature for 20 minutes, the mixture was treated with a solution of 8,9-dihydro-10-methylpyrido[1,2-a]indol-6(7H)-one (1.99 g) in tetrahydrofuran (25 ml) over 20 minutes. The mixture was stirred at -70° C. for 30 minutes, and a solution of 2-methyl-3-pyridinecarbaldehyde (1.21 g) in tetrahydrofuran (20 ml) was added dropwise over 20 minutes. After the mixture was stirred at -70° C. for further 60 minutes and at ambient temperature for 60 minutes, it was diluted with water and adjusted to pH 9 with oxalic acid. The separated organic layer was washed with brine, dried over anhydrous magnesium sulfate, and evaporated in vacuo, to give 8,9-dihydro-7-[(hydroxy)(2-methylpyridin- 3-yl)methyl]-10-methylpyrido[1,2-a]indol-6(7H)-one.
