US4328349A
Expired / Lapsed
US
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Process for preparing 5-methyl-4-imidazolecarboxylic acid esters
Assignee: SK&F LAB Co A CORP OF
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Filing: 1980-10-08
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Granted: 1982-05-04
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Expires: 2000-10-08
Abstract
Abstract A process for the preparation of 5-methyl-4-imidazolecarboxylic acid esters from acetoacetic acid esters. The products of this process are useful as intermediates for preparing cimetidine.
Inventors
- 👤 Harold Graboyes
- 👤 Thomas J. Kasper
- 👤 Praful D. Vaidya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:55
CPC Classifications
C; C07; C07D; C07D233/00; C07D233/54; C07D233/64; C07D233/66; C07D233/90
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
84 words
A process for preparing a compound of the formula: ##STR3## in which R is lower alkyl having 1-4 carbon atoms or benzyl, which comprises reacting an acetoacetate of the formula: ##STR4## with nitrous acid, reacting the resulting 2-hydroxyiminoacetoacetate of the formula: ##STR5## with formaldehyde and a mineral acid, and reacting the resulting α,β-dioxobutyrate of the formula: ##STR6## with aqueous ammonia and formaldehyde at pH of about 3 to 5 in which the three steps are carried out without isolating the 2-hydroxyiminoacetate and α,β-dioxobutyrate intermediates.
Claim 2
Dependent Claim
84 words
A process for preparing a compound of the formula: ##STR3## in which R is lower alkyl having 1-4 carbon atoms or benzyl, which comprises reacting an acetoacetate of the formula: ##STR4## with nitrous acid, reacting the resulting 2-hydroxyiminoacetoacetate of the formula: ##STR5## with formaldehyde and a mineral acid, and reacting the resulting α,β-dioxobutyrate of the formula: ##STR6## with aqueous ammonia and formaldehyde at pH of about 3 to 5 in which the three steps are carried out without isolating the 2-hydroxyiminoacetate and α,β-dioxobutyrate intermediates.
Claim 3
Dependent Claim
16 words
The process of claim 1 in which the 2-hydroxyiminoacetoacetate is reacted with formaldehyde and hydrochloric acid.
Claim 4
Dependent Claim
22 words
The process of claim 1 in which hydrochloric acid is added to a suspension of the 2-hydroxyiminoacetoacetate and formaldehyde at about 0°-15°.
Claim 5
Dependent Claim
19 words
The process of claim 1 in which the nitrous acid is generated by reacting sodium nitrite with an acid.
Claim 6
Dependent Claim
12 words
The process of claim 4 in which the acid is acetic acid.
Claim 7
Dependent Claim
20 words
The process of claim 4 in which the acetoacetate is reacted with sodium nitrite and acetic acid at about 0°-15°.
Claim 8
Dependent Claim
70 words
A process for preparing a compound of the formula: ##STR7## in which R is lower alkyl having 1-4 carbon atoms or benzyl, which comprises reacting a 2-hydroxyiminoacetoacetate of the formula: ##STR8## with formaldehyde and a mineral acid, and reacting the resulting α,β-dioxobutyrate of the formula ##STR9## with aqueous ammonia and formaldehyde at pH of about 3 to 5 in which the steps are carried out without isolating the α,β-dioxobutyrate intermediate.
Claim 9
Dependent Claim
70 words
A process for preparing a compound of the formula: ##STR7## in which R is lower alkyl having 1-4 carbon atoms or benzyl, which comprises reacting a 2-hydroxyiminoacetoacetate of the formula: ##STR8## with formaldehyde and a mineral acid, and reacting the resulting α,β-dioxobutyrate of the formula ##STR9## with aqueous ammonia and formaldehyde at pH of about 3 to 5 in which the steps are carried out without isolating the α,β-dioxobutyrate intermediate.
References Cited (Backward Citations)
GB1341375A
Cited
US3715365A
Cited
US3950333A
Cited
US3850953A
Cited
US4134983A
Cited
US4146724A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-03 | 1985-11-02 | 1986-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-03 | 1989-11-02 | 1990-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-03 | 1993-11-02 | 1994-05-04 | $7700.00 | Window Closed / Lapsed |