abstract |
The present invention relates to the preparation of β2 adrenergic receptor agonists in crystalline salt form. In particular, the present invention relates to the preparation of crystalline salts of compound (I), in particular crystalline monohydrochloride. The invention further relates to a novel crystalline form (polymorph) of the monohydrochloride salt of compound (Ia) and a process for its preparation. |