Task: Translation
Input (Czech): e en  se t²k  zp sobu v²roby opticky aktivn ch forem benzo[b]thiofen-5-ylderiv t  obecn ho vzorce 6a nebo 6b a jejich sol , kde R.sup.2.n. p°edstavuje atom vod ku nebo chr nic  skupinu hydroxylov  skupiny a R.sup.4.n. a R.sup.5.n., kter  jsou stejn  nebo r zn , p°edstavuj  alkylskupiny s 1 a  6 atomy uhl ku, kter² se prov d  tak,  e se p°i v²robn m postupu pou ije slou eniny vzorce 2a nebo 2b z skan  preferen n  krystalizac . Slou eniny obecn ho vzorce 6a a 6b zlep uj  mozkovou funkci.\
Output (English): The invention relates to a process for the production of optically active forms of benzo [b] thiophen-5-yl derivative in general formula 6a or 6b and a salt thereof, wherein R 2 is n. represents a hydrogen atom or a chromium group of a hydroxyl group and an R 4 group. and R.sup.5, which are the same or different, are alkyl groups of 1 and 6 carbon atoms, such that compounds of formula 2a or a compound of formula 2a are used in the art; 2b z skan preferen n krystalizac. The compounds of formula 6a and 6b improve brain function.