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

在中性pH的水溶液中，12元大环四胺的锌配合物能识别多种阴离子，与这些阴离子形成稳定的络合物。在此之前，我们已经报道了三硫氰尿酸的三阴离子(TCA^&lt；3-gt；)以4：4的比例组装成立方八面体超分子胶囊。这种超分子有一个内腔，里面包裹着大小匹配的疏水客体分子。立方八面体的一个突出性质是它的手性，而两种构筑块(Zn3L和TCA)都不含手性中心。本项目的目的是设计并合成一种具有光学活性的立方八面体。-(S，S)-2，5，8-11-四甲基环烯，((S，S)-锌)与三氯甲烷反应合成了(S，S)-锌^2：用LiAlH_4还原L-丙氨酸得到L-丙氨醇，2)L-丙氨醇与苯甲醛在NaBH_4存在下反应得到N-苄基-L-丙氨醇，3)N-苄基-L-丙氨醇与DEAD反应生成氮杂环丙氨酸衍生物，再与TsOH反应得到12元大环。这种光学活性的12元大环，(S，S)-2，5，8-11-四甲基环烯与(Boc)_2O反应得到(S，S)-2，5，8-11-tetramethyl-1，4，7-tris(tert-butyloxycarbonyl)cyclen.

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.