Chiral Schiff bases according to the general formula: STR1 and chiral transition metal complexes thereof, wherein at least the carbon atom of the monosaccharide to which the iminyl nitrogen atom is attached is asymmetric, and at least one of the carbon atoms adjacent the aforesaid carbon atom bears a hydroxyl group, R1 and R6 which may be the same or different, are hydrogen or lower alkyl, R2 is hydrogen, or lower alkyl or together with R10 forms a divalent hydrocarbon group, R3 is hydrogen, a sugar residue, or --CH2 OR10 in which R10 is hydrogen, lower alkyl or together with R2 forms a divalent hydrocarbon group, R4 is hydrogen or --CH2 OR10 in which R10 is hydrogen, or a lower alkyl, R5 is hydrogen, OR1 or a sugar residue, provided that both R4 and R5 are not hydrogen, R7 and R8 which may be the same or different, are hydrogen, or lower alkyl, or where p is 1, may with the cyclic ring to which CR7 R8 is attached form a fused system, R9 is hydrogen, alkyl, aralkyl, aryl or alkaryl, J is a chain of 3 or 4 atoms which with the group C A forms an aromatic system, which atoms may be carbon atoms or may be a mixture of carbon and one or more hetero atoms which may be the same or different, A is nitrogen, or STR2 or --NH--, L each of which may be the same or different, represents a substituent attached to a carbon atom in the chain J and is hydrogen, an alkyl group, aralkyl group, aryl, alkaryl or a substituent containing a hetero-atom; or two L's together with cyclic group to which they are attached form a fused system, m is 0 or 1, n is 0, 1 or 2, provided that n plus m is 0, 1, 2 or 3, p is 0, 1 or 2 and q is the number of carbon atoms in the chain J. The transistion metal is for example copper (II), chromium (II), manganese (II), iron (II), cobalt (II), nickel (II) or palladium (II). The aforesaid complexes may be used as catalysts in the cyclopropanation of olefins by diazoacetates to form insecticide or insecticide precursors.