Patent US3632850A successfully refreshed from Google Patents.
US3632850A
Expired / Lapsed
US
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Cephalexin synthesis
Assignee: Eli Lilly and Co
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Filing: 1969-03-18
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Granted: 1972-01-04
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Expires: 1989-03-18
Abstract
Abstract IN THE PREPARATION OF CEPHALEXIN FROM A PENICILLIN SULFOXIDE ESTER BY A SERIES OF STEPS INVOLVING EXPANSION OF THE PENICILLIN RING STRUCTURE TO THE CEPHALOSPORIN RING STRUCTURE, AN IMPROVEMENT IN YIELD AND EASE OF PROCESSING IS REALIZIED WHEN THE P-NITROBENZYL ESTER IS EMPLOYED.
Inventors
- 👤 William L Garbrecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:35
CPC Classifications
C; C07; C07D; C07D501/00; C07D501/14; C07D501/16; C07D501/20; C07D501/22; C07D499/00; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/55
Claims Analysis
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |