| 摘要 |
A process for preparing a compound of formula (3), includes the steps of: (a) providing an aqueous acidic solution including a compound of formula (1) and, as an impurity, a compound of formula (2); and (b) treating the aqueous acidic solution of step (a) such that the compound of formula (2) dehydrates to form a compound of formula (1) which is reduced to form an aqueous acidic solution of the compound of formula (3), the treating step (b) being carried out at one or more temperatures greater than ambient in the presence of a hydrogenation catalyst and hydrogen gas; and wherein for the compounds of formulae (1), (2) and (3): i) R1 is —OH, R2 is —OH and R3—H; or ii) R1 is —OCH3, R2 is —H and R3—CH3; or iii) R1 is —OH, R2 is —H and R3—CH3; or iv) R1 is —OCH3, R2 is —H and R3—H; or v) R1 is —OH, R2 is —H and R3—H; or vi) R1 is —OCH3, R2 is —OH and R3—H. |
