The invention relates to a process for preparing a C3-6 (hydro)fluoroalkene comprising dehydrohalogenating a C3-6 hydro(halo)fluoroalkane in the presence of a zinc/chromia catalyst, wherein the C3-6 (hydro)fluoroalkene produced is isomerized in the presence of the zinc/chromia catalyst.

The invention relates to a process for preparing a C3-6 (hydro)fluoroalkene comprising dehydrohalogenating a C3-6 hydro(halo)fluoroalkane in the presence of a zinc/chromia catalyst, wherein the C3-6 (hydro)fluoroalkene produced is isomerized in the presence of the zinc/chromia catalyst.

The presented invention relates to a process for preparation of compound of formula (I) or a salt or a solvate thereof (i.e.) siponimod. The invention also relates to intermediates used in the process and solid forms of these intermediates. ##STR00001##