反应详情

The 1-cyclohexyl derivative 5a was prepared in the current investigation from the enolic 4,5-dicarbethoxy-1-cyclohexyl-2,3-dioxopyrrolidine (1a) by a similar procedure conducted on nearly the same scale (ca. 0.088 mol of 1a used in many experiments). Both the 4,5-dicarbethoxy derivative 1a and the 4,5-dimethoxy derivative (mp 160° C.) have been used as starting materials with similar results. The procedure was identical with that described above for 5b, except that it was not necessary to conduct an evaporation to remove ethanol from the saponification mixture, which was instead filtered and poured into a mixture of 200 mL of ice and 50 mL of ethanol before acidification to precipitate the product. The typical yield of 5a, mp 154°-155° C., from 0.088 mol of starting material was 16 g (72%), a result equivalent to the best obtained from the more complex two-step conversion of 4-carbethoxy-1-cyclohexyl-2,3-dioxopyrrolidine described previously.

1. customan evaporation
2. customto remove ethanol from the saponification mixture, which
3. filtrationwas instead filtered
4. additionpoured into a mixture of 200 mL of ice and 50 mL of ethanol before acidification
5. customto precipitate the product