A process for preparing a compound of formula (I) where R
4
and R
5
are as defined in the specification; and R
6
is hydrogen or a protecting group, which process comprises cyclisation of a compound of formula (II) where R
4
, R
5
and R
6
are as defined in relation to formula (I), and R
7
is nitrogen-protecting group, and removing the group R
7
—, and thereafter if desired or necessary, removing any protecting group R
6
to obtain the corresponding carboxylic acid. Novel intermediates and the use of the products in the preparation of pharmaceutical compounds is also described and claimed.
一种制备式(I)化合物的工艺,其中 R
4
和 R
5
如说明书中所定义;以及 R
6
是氢或保护基团,该过程包括式(II)化合物的环化,其中 R
4
, R
5
和 R
6
如式(I)所定义,且 R
7
是氮保护基团,去掉基团 R
7
-,此后如果需要或有必要,去除任何保护基团 R
6
得到相应的
羧酸。本发明还描述了新型中间体及其在制备药物化合物中的用途。