Bis-oxazoline

Since 1980 the interest in this reaction increased because enantiospecificity was introduced and much more valuable products could be made. A wide variety of ligands was tested, such as chiral dipyridines, phenanthrolines, diphosphines, aminoalcohols, bis-oxazolines, bis-oxazolines with a third donor atom in the centre, bis-thioureas, diamines, etc [33], In 1981 the highest e.e. reported was still only 20%. For many years the best results were obtained with chiral diimines and phenanthrolines but e.e. s were below 70% [34], Pfaltz introduced bis-oxazolines for this reaction and obtained e.e. s as high as 91% [35] in 1991. 

Related Reagents. (5,5)-2,2 -(Dimethylmethylene)bis-(4-/-butyl-2-oxazoline) Bis(dimethylglyoximato)(methyl)(pyridine)-cobalt(III) Copper(II) Trifluoromethanesulfonate (15,95)-1,9-Bis [(/-butyl)dimethylsilyloxy]methyl -5-cyanosemicorrin (5)-2-[2-(Diphenylphosphino)phenyl]-4-phenyloxazoline Ethyl Diazoacetate. 

---