Process of producing 2-cyano-4-oxo-4H-benzopyran compounds
US5659051A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 11, 1994 |
| Grant date | Aug 19, 1997 |
| Priority date | — |
| Expiry date | Jul 11, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D311/24
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
There is disclosed a process of producing a 2-cyano-4-oxo-4H-benzopyran compound of the general formula (2): ##STR1## wherein R.sup.1 and R.sup.2 are independently hydrogen, halogen, hydroxy, C.sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, nitro or a group of the RCONH wherein R is C.sub.1 -C.sub.20 alkyl, phenyl, phenyl-substituted (C.sub.1 -C.sub.20) alkyl, phenyl (C.sub.1 -C.sub.20)alkoxyphenyl or (C.sub.1 -C.sub.20) alkoxyphenyl. This production process is characterized in that a carboxamide of the general formula (1): ##STR2## wherein R.sup.1 and R.sup.2 are each as defined above, is reacted with a dehydrating agent in the presence of a pyridine compound of the general formula (4): ##STR3## wherein A.sup.1 and A.sup.2 are independently hydrogen or C.sub.1 -C.sub.5 alkyl. If the final product cannot be obtained as crystals having good filtration properties by ordinary treatments, a novel technique as disclosed herein can provide such crystals by dissolving the reaction product in an organic solvent insoluble or slightly soluble in water; pouring the resultant solution into water; and removing the organic solvent by distillation with stirring to effect the crystallization of th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.