Derivatives of the tri-spirane pentaerythritoxy-cyclophosphazene compound, 1, have been used to investigate the stereogenic properties of spiranes combined with four equivalent conventional centres of chirality. In compound 1 the two inner rings are carbocyclic and symmetrical and the two outer rings are cyclotriphosphazenes substituted in different positions to provide the conventional centres of chirality. The case of combining spiranes with four equivalent centres of chirality has been investigated by the reaction of 1 with dimethylamine in a 1 : 8 molar ratio to give four diastereoisomeric products, in which the two cyclophosphazene rings are non-geminally di-substituted in either cis or trans configurations; viz. the cis–cis (2a), cis–trans (2b) and two trans–trans substituted dimethylamine derivatives 2c and 2d. The structure and stereogenic properties of compound 2a (C2 symmetry) have been characterized previously by both X-ray crystallography and 31P NMR spectroscopy on addition of a chiral solvating agent (CSA) and the structures and stereogenic properties of compounds 2b (C1) and 2d (C2) have been similarly characterized in this work. The structure of compound 2c has been characterised by X-ray crystallography and found to be meso with the relatively rare S4 symmetry. The four diastereoisomeric products 2a–2d represent all the possible stereochemical isomers of a spirane combined with four equivalent conventional centres of chirality.
三螺旋烷
季戊四醇氧基环
磷腈化合物1的衍
生物已被用于研究结合四个等效常规手性中心的螺旋烷的立体
化学性质。在化合物1中,两个内环是碳环且对称,两个外环是环三
磷腈,在不同的位置被取代,以提供常规的手性中心。通过1与
二甲基胺以1:8的摩尔比反应,得到四个非对映异构体产物,其中两个环
磷腈环以顺式或反式构型非成对地被取代,即顺式-顺式(2a)、顺式-反式(2b)和两个反式-反式取代的
二甲基胺衍
生物2c和2d。化合物2a(C2对称性)的结构和立体
化学性质之前已通过X射线晶体学和31P NMR光谱学在加入手性溶剂化剂(CSA)的情况下进行了表征,而化合物2b(C1)和2d(C2)的结构和立体
化学性质在本研究中得到了类似的表征。化合物2c的结构已通过X射线晶体学表征,并发现其具有相对罕见的S4对称性。四个非对映异构体产物2a-2d代表了结合四个等效常规手性中心的螺旋烷的所有可能的立体
化学异构体。