| abstract |
The present invention provides a method for regeneration of chiral 2,2'-cyclopropylidene-bis(oxazolines), such as (3aR,3'aR,8aS,8'aS)-2,2'-cyclopropylidene-bis-[3a,8a]-dihydro-8H-indeno[1,2-d]oxazole and (4S,4'S,5R,5'R)-2,2'-cyclopropylidene-bis-4,5-diphenyldihydro-4,5-oxazole, used as a part of complex catalysts for e.g. stereoselective addition reactions, from the reaction mixtures, by selective sorption of 2,2'-cyclopropylidene-bis(oxazolines) on a sorbent, such as silica gel, isolation of the sorbent from reaction mixture, desorption of 2,2'-cyclopropylidene-bis(oxazolines) from the sorbent with suitable organic sorbent and final recovery of 2,2'-cyclopropylidene-bis(oxazolines) from the organic solvent used for desorption process. Catalytic quality of recovered compounds does not differ from those in freshly prepared catalysts. |