CRYSTAL-STRUCTURE OF THE KETO-ENAMINE FORM OF (-(2-HYDROXYBENZYLIDENE)AMINE-L-PHENYL-L,3 PROPALLEDIOL()(1S,2S)2)

The title compound crystallizes in the orthorhombic space group P2(1)2 (1)2(1), With Z = 4, a = 6.068(1)Angstrom, b = 10.922(1)Angstrom, and c = 21.713(2)Angstrom. The compound is the chiral ligand of a copper c omplex used as an enantioselective catalyst. It crystallizes from meth anol in the keto-enamine form, though the enol-imine isomer predominat es in the solution. Most N-salicylideneamines studied by X-ray are eno l-imines. The two tautomeric forms may interchange through an intramol ecular hydrogen bond and the distances between non-II atoms in the res ulting cyclic -O-H ... N=C-C=C- or -C=O ... H-N-C=C- fragment may be m isleading, so that H atom position is the crucial factor for determina tion of the proper tautomeric form.