反应详情

6 g (19.52 mmol) of (8R,9R)-2,3-dimethyl-8-hydroxy-9-phenyl-7,8,9,10-tetra-hydroimidazo-[1,2-h][1,7]naphthyridin-7-one (ee>90%, Daicel Chiralcel HPLC) are suspended in 60 ml of methanol and cooled to −5° to 0° C. in a methanol-ice bath. At this temperature, sodium borohydride (0.81 g, 21.47 mmol) is added by spatula during the course of 0.5 h (evolution of gas). After addition is complete, the mixture is stirred for a further 10 min, and then concentrated in a vacuum rotary evaporator at a bath temperature of 40° C. The oily residue obtained is taken up in distilled water and extracted three times with chloroform. The organic phases are combined and washed with a little water, then dried using anhydrous sodium sulfate and filtered. The filtrate is concentrated on a vacuum rotary evaporator and co-evaporated with acetone; the title compound crystallizes out in the course of this. The precipitate is filtered off, washed with acetone and dried to constant weight at 50° C. in a vacuum drying oven. 5.15 g (85.3%, ee>90%, Daicel Chiralcel HPLC) of the title compound are obtained as a colorless crystallizate of melting point 206-9° C.

1. temperaturecooled to −5° to 0° C. in a methanol-ice bath
2. additionAfter addition
3. concentrationconcentrated in a vacuum rotary evaporator at a bath temperature of 40° C
4. customThe oily residue obtained
5. extractionextracted three times with chloroform
6. washwashed with a little water
7. customdried
8. filtrationfiltered
9. concentrationThe filtrate is concentrated on a vacuum rotary evaporator and co-evaporated with acetone
10. customthe title compound crystallizes out in the course of this
11. filtrationThe precipitate is filtered off
12. washwashed with acetone
13. customdried to constant weight at 50° C. in a vacuum
14. customdrying oven