4,5-dihydro-2-(2-phenylethyl)-6H-imidazo[4,5,1-ij]-quinolin-6-one → 5,6-dihydro-2-(2-phenylethyl)-4H-imidazo[4,5,1-ij]quinolin-6-ol

Participants

Reaction Steps

(+)-Diisopinocanphenylchloroborane (87.2 g) was dissolved in dry tetrahydrofuran (170 mL) under an argon atmosphere. Fifty grams of the 4,5-dihydro-2-(2-phenylethyl)-6H-imidazo[4,5,1-ij]quinolin-6-one obtained in Example 1 was dissolved in 340 mL of dry tetrahydrofuran and the solution was added slowly at -20° C. to -25° C. After stirring for 3 hrs at the same temperature, the solvent was removed under reduced pressure. The residue was dissolved in ethyl acetate (700 mL) and, following the addition of diethanolamine (52.2 mL), the mixture was stirred at room temperature for 2 hrs. The precipitate was separated by filtration and washed with ethyl acetate; thereafter, the filtrate was concentrated. The residue was purified by silica gel column chromatography to yield 40 g of the titled compound with an optical purity of 76.2% ee. The compound was recrystallized from a solvent system consisting of a mixture of ethanol (100 mL) and hexane (400 mL) to yield the titled compound with an optical purity of 99.6% ee or more as colorless crystals (17.4 g).

Provenance & Evidence