Process for obtaining 6-fluoro-3,4-dihydro-2h-chromen-2-yl-ethanol derivatives and (s*)-2-chloro-14(r*)-6-fluoro-3,4-dihydro-2h-chromen-2-yl)-ethanol compound of diastereomeric excess

摘要

The present invention relates to a process for reducing a compound of formula (I) wherein X is halogen, a hydroxy group, an alkylsulfoniloxy group or an arylsulfonyloxy group; to give a compound of formula (II) as a diastereoisomerically pure compound of RS/SR configuration characterized in that said reduction is carried out by the use of (+)-B-chlorodiisopinocampheylborane or (−)-B-chlorodiisopinocampheylborane. The compounds of formula (II) are useful as intermediates for the preparation of Nebivolol.