反应详情

温度

0 °C

The product of stage (a) (10 g) was stirred for 4 hr with 1 M lithium hydroxide (30.5 ml). The mixture was extracted with ether, the aqueous phase cooled to 0° C. and acidified to pH 1.0 with 2 N.HCl and extracted with ethyl acetate, exhaustively. The extracts were dried after washing with brine to give a solid residue. The solid was dissolved in a mixture of ether (35 ml) and ethylacetate (35 ml) and DCHA (4.37 g) added. After refrigeration, the precipitated DCHA salt (m.p. 136°-140°) was filtered and washed with ether. The salt was partitioned between ethyl acetate and 5% citric acid solution, the ethyl acetate extract washed with brine and evaporated in vacuo to give the desired product as a crystalline solid m.p. 94°-98° C.

1. extractionThe mixture was extracted with ether
2. extractionHCl and extracted with ethyl acetate
3. customThe extracts were dried
4. washafter washing with brine
5. customto give a solid residue
6. additionadded
7. filtrationAfter refrigeration, the precipitated DCHA salt (m.p. 136°-140°) was filtered
8. washwashed with ether
9. customThe salt was partitioned between ethyl acetate and 5% citric acid solution
10. extractionthe ethyl acetate extract
11. washwashed with brine
12. customevaporated in vacuo