Three kinds of novel α-monosubstituted cyclododecanone oximes were synthesized by the reaction of α-monosubstituted cyclododecanone with hydroxylamine. The X-ray diffraction analysis showed that they had different conformations, in which the parent ring took [3333] and [2334] conformation and the substituting group was at α-side-exo or α-corner-anti position. These results were rationalized by "corner-position carbonyl participation" of raw materials, "memory effect", and hydrogen-bonding between hydroxylamine and α-monosubstituted cyclododecanone. In general, an amine molecule approaches cyclododecanone with the bigger groups or intramolecular H-bonding from the side with less hindrance or not breaking hydrogen-bond, resulting in α-corner-anti monosubstituted cyclododecanone oximes, whereas an approach of an amine molecule from the other side with a strong hydrogen bonding network gives rise to α-side-exo monosubstituted cyclododecanone oximes. When cyclododecanone with smaller groups or weak intermolecular H-bonding, an amine molecule approaches from both sides to afford α-side-exo and α-corner-anti monosubstituted cyclododecanone oximes.

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