Synthesis And Application Of Planar Chiral[2.2]Paracyclophanyl Macrocyclic Complexes

The structure of the chiral ligand has been an important factor of success for the asymmetric catalytic reactions, so, according to the response characteristics of the design and synthesis of new ligands is still the top priority of the catalytic asymmetric reaction. The central, axis, planar and helical chirality are the factors of building chiral ligand. Planar chiral [2.2]paracyclophane derivatives are the typical representative of the planar chiral ligands, since the late1990s, these compounds as a new class of chiral ligands used to asymmetric catalysis research gradually have increased. Planar chiral plays an increasingly important role in homogeneous organometallic catalysis.[2.2]paracyclophane (PCP) is a three-dimensional aromatic molecule with rigid arrangement of parallel, eclipsed benzene rings connected by the ethylene.Because its special structural features, molecules based on PCP have been designed to mimic through-space delocalization of excited energy, probe intramolecular charge transfer across the transannular gap and understand the global transannular π-π interactions. In recently, molecules based on PCP are usually used to build artificial photosynthesis system as a special spacer different from many other groups like acetylene, benzene, etc.For these reasons, our interest of research [2.2]paracyclophane has never been weakened, we have designed and synthesized a series of helical compounds based on planar chiral [2.2]paracyclophane, and have tried to apply it to the asymmetric catalysis. We also synthesized a series of macrocyclic imidazoliums or imidazoliniums derived from imino or amino[2.2]paracyclophane and used as ligands to prepare copper, silver and other metal macrocyclic complexes, and tried to apply in asymmetric catalytic reactions.The contents of this paper are mainly the following aspects:The first part, Synthesis of the planar chiral [2.2]paracyclophane and its derivatives.First, by Hoffman elimination we synthesized the [2.2]paracyclophane, and then transformed to4,12-dibromo [2.2] paracyclophane via bromination. Our target compounds,4-amino-12-bromo [2.2] paracyclophane and4,12-diamino [2.2] paracyclophane are two important structural units, and also important intermediates. Synthesis and resolution of these two compounds are achieved by using the methods found in our laboratory.4-Amino-12-bromo [2.2]paracyclophane has an important feature of the spatial structure that can be modified more easily.4,12-Diamino [2.2]paracyclophane, and connected by different ether chain amino [2.2]paracyclophane derivatives reacted with glyoxal solution in THF at room temperature to gave the corresponding macrocyclic imine.The second part, synthesis and modification of cyclophanes with planar and helical chirality derived from [2.2]paracyclophane.First, the planar chiral tetraamine can be obtained by reduction of macrocyclic imine derived from [2.2]paracyclophane with borane. Tetraalkyl substituted planar chiral tetraamines were obtained by reduction of the tetraamide with LiAlH4or borane, which could be got from acetylation of tetraamine. The tetraalkyl substituted tetraamines were also gained through methylation of the tetraamines with dimethyl sulfate.The third part, the synthesis of imidazolinium salts and their metal complexes.Macrocyclic bisimidazolinium was prepared by cyclization reaction using chiral macrocyclic tetraamine with triethyl orthoformate and ammonium fluoroborate. The bisimidazolinium bromid has been gotten from its fluoroborate by ions exchange with lithium bromide or tetrabutyl ammonium bromid. Finally, the bisimidazolinium bromide can react with silver oxide or cuprous oxide to afford the chiral macrocyclic carbene-Cu or Ag complexes.