Synthesis of optically active nanoscale supramolecular capsule and its application to chiral recognition and asymmetric synthesis

已有研究证实，12元大环四胺（Zn^<2+>-cyclen）的Zn^<2+>配合物在中性ph的水溶液中可以识别多种阴离子，并与这些阴离子形成稳定的配合物。在此之前，我们报道了三（Zn^<2+>-cyclen） （Zn_3L^1）与三硫氰尿酸的三阴离子（TCA^<3->）在水溶液中以4:4的比例组装形成立方面体超分子囊。这种超级分子具有一个内腔，其中大小匹配和疏水的客体分子被封装。立方面体的一个突出性质是其手性，而两种构建块（Zn3L和TCA）都不含手性中心。本项目的目的是用TCA自组装Zn^<2+>-cyclen, Zn^<2+>-(S，S，S，S)-2,5,8-11-四甲基cyclen， （(S，S，S，S)- znl ^2）的手性衍生物，设计并合成具有光学活性的立方面体。（S，S，S，S）-ZnL^2的合成方法如下：1)l-丙氨酸用LiAlH_4还原得到l-丙氨酸，2)l-丙氨酸在NaBH_4存在下与苯甲醛反应得到n -苄基- l-丙氨酸，3)n -苄基- l-丙氨酸与DEAD反应得到氮化吡啶衍生物，该衍生物与TsOH反应得到12元大环。该具有光学活性的12元大环（S，S，S，S）-2,5,8-11-四甲基环与（Boc）_2O反应生成（S，S，S，S）-2,5,8-11-四甲基-1,4,7-三（叔丁基氧羰基）环。

It has been establisehd that Zn^<2+> complex of a 12-membered macrocyclic tetraamine (Zn^<2+>-cyclen) recognize a variety of anions to form a stable complexes with these anions in aqueous solution at neutral pH. Previously, we have reported that tris(Zn^<2+>-cyclen) (Zn_3L^1) and trianion of trithiocyanuric acid (TCA^<3->) assembly in a 4:4 ratio to form a cuboctahedral supramolecular capsule in aqueous solution. This supermolecule possesses an inner cavity, in which size-matched and hydrophobic guest molecules are encapsulated. One of outstanding properties of the cuboctrahedron was its chirality, while both building blocks (Zn3L and TCA) contain no chiral center.The purpose of this project is to design and synthesize an optically active cuboctahedron by self-assembly of a chiral derivative of Zn^<2+>-cyclen, Zn^<2+>-(S,S,S,S)-2,5,8-11-tetramethylcyclen, ((S,S,S,S)-ZnL^2), with TCA.(S,S,S,S)-ZnL^2 was synthesized as follows : 1)L-alanine was reduced with LiAlH_4 to yield L-alaninol, 2)L-alaninol was reacted with benzaldehyde inthe presence of NaBH_4 to give N-benzyl-L-alaninol, 3)N-benzyl-L-alaninol was reacted with DEAD and yielded an aziridine derivative, which was reacted with TsOH to give a 12-membered macrocycle. This optically active 12-membered macrocycle, (S,S,S,S)-2,5,8-11-tetramethylcyclen, was reacted with (Boc)_2O to afford (S,S,S,S)-2,5,8-11-tetramethyl-1,4,7-tris(tert-butyloxycarbonyl)cyclen.