There is described an improved process for the production of the biologically active compound 6,7,8,9-tetra- hydro-5-hydroxy-4-oxo-10-propyl-4H-naphtho [2,3-b] pyran-2-carboxylic acid of the formula
which comprises hydrolysis of 6,7,8,9-tetrahydro-5-diazo-4-oxo-1 0-propyl-4H-naphtho [2,3-b] pyran-2-carboxylic acid or an ester thereof, characterised in that the hydrolysis is carried out in the presence of less than 10% w/w nitrite anion. The diazo compound may be made by diazotisation of 6,7,8,9-tetrahydro-5-amino-4-oxo-10-propyl-4H-naphtho [2,3-b] pyran-carboxylic acid or an ester thereof in the presence of nitrous acid.
本发明描述了一种生产
生物活性化合物 6,7,8,9-四氢-5-羟基-4-氧代-10-丙基-4H-
萘并[2,3-b]
吡喃-2-
羧酸的改进工艺,其式如下
其中包括 6,7,8,9-四氢-5-重氮-4-氧代-1 0-丙基-4H-
萘并[2,3-b]
吡喃-2-
羧酸或其酯的
水解,其特征在于
水解是在
亚硝酸阴离子少于 10%w/w的存在下进行的。重氮化合物可通过 6,7,8,9-四氢-5-
氨基-4-氧代-10-丙基-4H-
萘并[2,3-b]
吡喃
羧酸或其酯在
亚硝酸存在下的重氮化反应制得。