Molecular geometry and optical activity of N-nitroso-2,2,6,6-tetramethylpiperidines generated by spontaneous crystallization and inclusion complexation with optically active diols
作者:Teresa Olszewska、Maria Gdaniec、Tadeusz Połoński
DOI:10.1016/j.tetasy.2009.05.008
日期:2009.6
complexes revealed that in all cases the guest nitrosamines assume chiral conformations as seen by their chiroptical spectra. The optically active nitrosamines are configurationally labile and rapidly racemize in solution. The solid state structures revealed that in order to avoid an allylic 1,3-strain [A(1,3)], caused by an interaction of the nitrosamino group with the methyl substituents, the piperidine
获得了三种空间应变的N-亚硝胺及其与旋光性二醇(TADDOLs)的包合物,并描述了它们的固态晶体结构。由于形成了N-亚硝基-4-羟基-2,2,6,6-四甲基哌啶2作为可自发分解的团聚体晶体(空间群P 3 2),因此对其固态CD进行了测量。包合物的晶体结构表明,在所有情况下,客人的亚硝胺都具有手性构象,如它们的手性光谱所见。旋光的亚硝胺在结构上不稳定并且在溶液中迅速消旋。固态结构表明,为了避免烯丙基1,3-应变[A(1,3) ],由于亚硝胺基与甲基取代基的相互作用,在1和2中的哌啶环呈现在氨基氮上显着扁平的椅子构象,而在4-氧代衍生物3中,哌啶环呈现a扭船的构象。