Two kinds of α-monosubstituted cyclododecanone oximes and thiosemicarbazones were synthesized by the reaction of α-monosubstituted cyclododecanone with hydroxylamine and 4-p-tolylthiosemicarbazide. The X-ray diffraction analysis showed that they had different conformations, in which the parent ring takes still [3333] conformation and the substituting group is at α-side-exo or a-corner-anti position. These results were rationalized by “corner-position carbonyl participation” of raw materials, “memory effect” and H-bonding between hydroxylamine or 4-p-tolylthiosemicarbazide and α-monosubstituted cyclododecanone. In general, an amine molecule approaches cyclododecanone from the side with less hindrance, resulting in α-corner-anti monosubstituted cyclododecanone oximes or thiosemicarbazones, whereas an approach of an amine molecule from the other side where hydrogen bonding occurs gives rise to α-side-exo monosubstituted cyclododecanone oximes or thiosemicarbazones.

Key words: α-monosubstituted cyclododecanone oxime, α-monosubstituted cyclododecanone thiosemicarbazone, crystal structure, corner-position carbonyl participation, memory effect