| 摘要 |
<p>The invention provides a process for the preparation of a water-soluble salt of formula (I) wherein: R1 is hydroxy or C1-C4 alkoxy, or R1 and an adjacent R2 together form a methylenedioxy ring; each R2 is independently H, C1-C3 alkyl, C1-C2 alkoxy, OH or carboxymethoxy provided that at least two R2 groups are H; R3 is H or methyl; and Xn+ is a food-acceptable cation wherein n=1,2,3 or 4, said process comprising the steps of: providing an alcoholic solution of a compound of formula (II) wherein R¿4? is OH or a carboxylate protecting group and the solvent for said solution comprises one or more C1 to C6 alcohols; and treating said solution with an alkali salt of X?n+¿ in the presence of at least 0.5 % w/v of water to precipitate said compound of formula (I) from said alcoholic solution. The presence of a small amount of water in the reaction mixture results in a more tractable product of higher yield and purity.</p> |
