Patent US2855406A successfully refreshed from Google Patents.
US2855406A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of benzopyrans and benzofurans
Assignee: Individual
•
Filing: 1956-05-02
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Granted: 1958-10-07
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Expires: 1976-05-02
Abstract
No abstract record available.
Inventors
- 👤 Dann Otto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:49
CPC Classifications
C; C07; C07D; C07D493/00; C07D493/02; C07D493/04; C07D307/00; C07D307/77; C07D307/78; C07D307/86
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
59 words
A PROCESS WHICH COMPRISES REACTING 3-OXO-4,7-DI-R6-HYDROXY-2,3-DIHYDROBENZOFURAN WITH HYDROXYLAMINE THEREBY PRODUCING 3-OXIMIDO-4-7-DI-R-6-HYDROXY-2,3-DIHYDROBENZOFURAN, REDUCING THE LATTER THEREBY PRODUCING 3-AMINO-4,7-DI-R-6-HYDROXY-2,3-DIHYDROBENZOFURAN, SPLITTING OUT AMMONIA FROM THE LATTER THEREBY PRODUCING 4,7-DI-R-6-HYDROXY-BENZOFURAN, REACTING THE LATTER WITH B-HALO-CROTONIC ACID LOWER ALKYL ESTER THEREBY PRODUCING 4,7-DI-R-6-(1-LOWER CARBALKOXY-1-PROPEN-2-YLOXY) BENZOFURAN, HYDROLYZING THE LATTER THEREBY PRODUCING 4,7-DIR-6-(1-CARBOXY-1-PROPEN-2-YLOXY)-BENZOFURAN, AND CYCLIZING THE LATTER THEREBY PRODUCING 4,9-DI-R-7-METHYLFURO(3.2-G)(1)BENZOPYRAN-5-ONE; R REPRESENTING A LOWER ALKOXY RADICAL.
Claim 2
Dependent Claim
59 words
A PROCESS WHICH COMPRISES REACTING 3-OXO-4,7-DI-R6-HYDROXY-2,3-DIHYDROBENZOFURAN WITH HYDROXYLAMINE THEREBY PRODUCING 3-OXIMIDO-4-7-DI-R-6-HYDROXY-2,3-DIHYDROBENZOFURAN, REDUCING THE LATTER THEREBY PRODUCING 3-AMINO-4,7-DI-R-6-HYDROXY-2,3-DIHYDROBENZOFURAN, SPLITTING OUT AMMONIA FROM THE LATTER THEREBY PRODUCING 4,7-DI-R-6-HYDROXY-BENZOFURAN, REACTING THE LATTER WITH B-HALO-CROTONIC ACID LOWER ALKYL ESTER THEREBY PRODUCING 4,7-DI-R-6-(1-LOWER CARBALKOXY-1-PROPEN-2-YLOXY) BENZOFURAN, HYDROLYZING THE LATTER THEREBY PRODUCING 4,7-DIR-6-(1-CARBOXY-1-PROPEN-2-YLOXY)-BENZOFURAN, AND CYCLIZING THE LATTER THEREBY PRODUCING 4,9-DI-R-7-METHYLFURO(3.2-G)(1)BENZOPYRAN-5-ONE; R REPRESENTING A LOWER ALKOXY RADICAL.
References Cited (Backward Citations)
GB663369A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-10-06 | 1962-04-07 | 1962-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-10-06 | 1966-04-07 | 1966-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-10-06 | 1970-04-07 | 1970-10-07 | $7700.00 | Window Closed / Lapsed |