New unsymmetrical chiral salen complexes were synthesized and the efficiency of Mn(III), Ti(IV), Co(II) and Co(III) type catalysts were examined in the enantioselective epoxidation of styrene and alpha-methylstyrene, the trimethylsilylcyanation of benzaldehyde, the borohydride reduction of aromatic ketones and asymmetric hydrolysis of epoxides to diols, respectively. A very high level of enantioselectivity was attainable over the unsymmetrical chiral salen complexes prepared mainly from salicylaldehyde and 2-formyl-4,6-di-tert-butylphenol derivatives. Enantiomeric excess of the corresponding reaction product obtained using unsymmetrical chiral salen catalysts was generally higher than that over conventional symmetric chiral salen catalysts.