Claims
- 1. A process for the preparation of a diketopiperazine of the formula ##STR4## which comprises (a) cyclizing aspartame by means of an acidic cyclizing agent selected from the group consisting of mineral and organic protonic acids, cationic acidic resins and acidic diatomaceous earth, in a suspension or solution in a lower aliphatic alcohol at a temperature of from about 100.degree. to 150.degree. C. and at a pressure higher than atmospheric pressure, and (b) subsequently treating the resulting reaction mixture with ammonia at a temperature of from about 80.degree. to 120.degree. C. and at a pressure higher than atmospheric pressure.
- 2. Process according to claim 1, wherein the acidic cyclizing agent is an acidic diatomaceous earth.
- 3. Process according to claim 1, whrein the cyclization is carried out in methanol.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8589/75 |
Jul 1975 |
CH |
|
13499/75 |
Oct 1975 |
CH |
|
Parent Case Info
This is a division of application Ser. No. 700,168, filed June 28, 1976, now U.S. Pat. No. 4,038,429, granted July 26, 1977.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3563992 |
Harnden |
Feb 1971 |
|
4038429 |
Smith et al. |
Jul 1977 |
|
Divisions (1)
|
Number |
Date |
Country |
Parent |
700168 |
Jun 1976 |
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