Process of producing 2-cyano-4-oxo-4h-benzopyran compounds

Details Process of producing 2-cyano-4-oxo-4h-benzopyran compounds Process of producing 2-cyano-4-oxo-4h-benzopyran compounds

C - Chemistry, Metallurgy

07

D

C07D 311/24 (2006.01)

Patent

CA 2127945

The present invention is directed to a process of producing a 2-cyano-4- oxo-4H-benzopyran compound of the general formula (2): (see formula II) wherein R1 and R2 are independently hydrogen, halogen, hydroxy, C1-C5 alkyl, C1-C5 alkoxy, nitro or a group of the formula RCONH wherein R is C1-C20 alkyl, phenyl, phenyl-substituted(C1-C20)alkyl, phenyl(C1-C20)alkoxyphenyl, or (C1- C20)alkoxyphenyl. This production process is characterized in that a carboxamide of the general formula (1): (see formula I) wherein R1 and R2 are each as defined above, is reacted with a dehydrating agent in the presence of a pyridine compound of the general formula (4): (see formula IV) wherein A1 and A2 are independently hydrogen or C1-C5 alkyl. If the final product cannot be obtained as crystals having good filtration properties by ordinary treatment, 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 crystallization of the final product.

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