反应详情

To a solution of sodium hydroxide (48 g, 1.2 mol in 800 ml of water) was charged compound 1c (80 g, 0.24 mol) at 25–30° C. The resulting dark black-red coloured solution was heated to mild reflux (reaction mixture temperature ˜85–90° C.) and was held for 90 minutes. This was then treated with activated carbon and refluxed further for 30 minutes. Then the reaction mixture was cooled to 45–50° C. and was filtered through a celite bed (prepared in water). The celite bed was washed with water (4×80 ml) and was mixed with the main filtrate. Further 240 ml of water was added to the combined filtrate and washings and cooled to 25–30° C. with efficient stirring. The pH of this resulting solution was adjusted to 6.0±0.05 with dropwise addition of 20% v/v aqueous acetic acid over 30–45 minutes. The resulting yellow slurry was cooled to 0–5° C. and stirred for 30 minutes to complete the crystallization. Compound 1d thus obtained was filtered and washed with water (2×160 ml) followed by isopropanol wash (2×40 ml). The wet cake obtained (107 g) was dried at 70° C. under reduced pressure (˜650 mm of Hg) for 16 hours to constant weight. The title compound 1d was obtained in 65% yield (55 g).

1. temperatureThe resulting dark black-red coloured solution was heated
2. temperatureto mild reflux
3. custom(reaction mixture temperature ˜85–90° C.)
4. additionThis was then treated with activated carbon
5. temperaturerefluxed further for 30 minutes
6. temperatureThen the reaction mixture was cooled to 45–50° C.
7. filtrationwas filtered through a celite bed (prepared in water)
8. washThe celite bed was washed with water (4×80 ml)
9. additionwas mixed with the main filtrate
10. additionFurther 240 ml of water was added to the combined filtrate and washings
11. temperaturecooled to 25–30° C. with efficient stirring
12. additionThe pH of this resulting solution was adjusted to 6.0±0.05 with dropwise addition of 20% v/v aqueous acetic acid over 30–45 minutes
13. temperatureThe resulting yellow slurry was cooled to 0–5° C.
14. customthe crystallization