α-单取代环十二酮肟及缩氨基硫脲的合成及晶体结构

Synthesis and Crystal Structure of α-Monosubstituted Cyclododecanone Oxime and Thiosemicarbazone

单晶X射线衍射分析表明,α-单取代环十二酮与氨衍生物羟胺和氨基硫脲发生缩合反应得到两种母体构象均为[3333],而取代基为边外向或角反向的α-单取代环十二酮肟或缩氨基硫脲.利用底物的"角位羰基参与反应"原理,"记忆效应"及进攻试剂与底物是否形成氢键解释了这一实验结果.通常情况下,试剂从空间障碍小的一面进攻羰基而生成α-角反取代环十二酮肟或缩氨基硫脲.当试剂与底物的取代基之间能够形成分子间氢键时,则生成α-边外取代环十二酮肟或缩氨基硫脲.

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 α-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.