2,5-dioxopiperazine compounds and method for preparing .alpha.-aspartyl-L-phenylalanine methyl ester derivatives
AssigneeAjinomoto Co., Inc.
InventorsTadashi Takemoto, Ryoichiro Nakamura
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Abstract
A method of preparing .alpha.-APM derivatives without using an expensive L-phenylalanine is provided, wherein 2,5-dioxopiperazine-3-acetamide is reacted with acetic anhydride to give N,N'-diacetyl-6-cyanomethyl-2,5-dioxopiperazine, which is then reacted with benzaldehyde in the presence of a strong base to give 1-acetyl-3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine. This is treated with hydrazine to give 3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine, which is then reduced to prepare 3-benzyl-6-cyanomethyl-2,5-dioxopiperazine, which is converted by reaction with methanol in the presence of a strong acid to an .alpha.-APM derivative for use as a sweetener.
Claims18
A method for preparing 3-benzyl-6-cyanomethyl-2,5-dioxopiperazine (I), comprising:
- reacting 2,5-dioxopiperazine-3-acetamide (II) with acetic anhydride to provide N,N'-diacetyl-6-cyanomethyl-2,5-dioxopiperazine (III),
- condensing (III) with benzaldehyde in the presence of a strong base to provide 1-acetyl-3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine (IV),
- treating (IV) with hydrazine to provide 3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine (V);
- and
- reducing (V) to give (I).
A method for preparing 3-benzyl-6-cyanomethyl-2,5-dioxopiperazine (I), comprising:
- reacting 2,5-dioxopiperazine-3-acetamide (II) with acetic anhydride to provide N,N'-diacetyl-6-cyanomethyl-2,5-dioxopiperazine (III);
- condensing (III) with benzaldehyde in the presence of a strong base to provide 1-acetyl-3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine (IV);
- reducing (IV) to provide 1-acetyl-3-benzyl-6-cyanomethyl-2,5-dioxopiperazine (VI);
- and
- treating (VI) with hydrazine to provide (I).
A method for preparing an .alpha.-L-aspartyl-L-phenylalanine methyl ester compound, comprising:
- treating 3-benzyl-6-cyanomethyl-2,5-dioxopiperazine (I) with methanol in the presence of a strong acid.
3-Benzyl-6-cyanomethyl-2,5-dioxopiperazine.
3-Benzylidene-6-cyanomethyl-2,5-dioxopiperazine.
N,N'-Diacetyl-6-cyanomethyl-2,5-dioxopiperazine.
1-Acetyl-3-benzyl-6-cyanomethyl-2,5-dioxopiperazine.
1-Acetyl-3-benzylidene-6-cyanomethyl-2,5-dioxopiperazine.
Dependencies are inferred from the claim text.