Patent 7750156 was granted and assigned to Otsuka Pharmaceutical on July, 2010 by the United States Patent and Trademark Office.
The present invention provides an industrially advantageous method of producing aminophenol compounds represented by the formula (1) by a simple and easy procedure at a high yield and a high purity. The present invention provides a method of producing an aminophenol compound represented by the formula (1): (wherein each of R1 and R2, which may be the same or different, is a hydrogen atom, a substituted or unsubstituted lower alkyl group or the like; R1 and R2, taken together with the adjacent nitrogen atom, may form a 5- or 6-membered heterocycle with or without other intervening heteroatoms; the heterocycle may be substituted by 1 to 3 substituents selected from the group consisting of a hydroxyl group, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group and the like; and the hydroxyl group in the formula (1) is substituted on the 2- or 4-position to the amino group on the phenyl ring), which comprises allowing a cyclohexanedione compound represented by the formula (2) to react with an amine compound represented by the formula (3) (wherein R1 and R2 are as defined above), under a neutral or basic condition.