Synthesis,Arylation And Chiral Characterization Of Double Helical Based On Cyclohexylenetetramine

The double helical compounds have presented potential usage in asymmetric catalysis,molecular machines,molecular motors,molecular recognition.As known,artificial double helix structures are mainly synthesized via two helical chains connected by the covalent bond and/or non-covalent bond（hydrogen bond,coordination bond,etc.）.While the construction of double helical structures based on covalent bond is limited to one-dimensional linear structure and the big challenge exists in the development of more complicated spiral structures due to the poor solubility of the intermediates and the low yield at purification.Based on our previous work on cyclooctatetrathiophene（COTh）,studies have been carried out in this manuscript to further optimize the synthetic route and trial of building more complex two-dimensional double helical oligomers.In addition,resolution of the double helical oligomers have been carried out by HPLC,which may provide potential utilization for these chiral double helix and make the basis for the development of novel double helical compounds.In this thesis,two double helical compounds DH-1 and DH-2 are selected as the target molecules and a series of derivatives were prepared since they contained the reactiveα-site of the thiophene rings;studies related to the chiral properties of the derivatives are also investigated.The main contents are as following in four parts:Optimization of the synthetic route to double helical of DH-1 molecule.After carefully analyzing the previous synthetic route,the double helical compound DH-1 is successfully prepared for using Negishi coupling of compound I₄-COTh-1 and zinc intermediate of2,2’-dibromo-5,5’-bis（trimethylsilane）-3,3’-bithiophene and the yield of the target molecule increased from5-15%to 30%.The molecular structure has been fully characterized by NMR,IR,HRMS and X-ray single crystal diffraction.2.Arylation of the double helical DH-1,DH-2 molecules.1)DH-1 derivatives with end-capped phenyl or thienyl ringsVia the four reactiveα-sites on the thiophene ring in the DH-1 molecule,the double helical DH-1-Th and DH-1-Ph have been successfully prepared by attaching the ending thiophene and benzene rings.The molecular structure has been fully characterized by NMR,IR,HRMS and X-ray single crystal diffraction.2)DH-2 derivatives with end-cappedα-Naphthyl and/orβ-NaphthylVia Negishi coupling reactions,DH-2 derivatives with end-cappedα-Naphthyl and/orβ-Naphthyl（DH-2-Np-1 and DH-2-Np-2）have been successfully prepared and they have been confirmed by NMR,IR and HRMS.In addition,compound DH-2-Np-1 and DH-2-Np-2 have also been characterized by X-ray single crystal diffraction.The results show that the introduction of naphthyl can increase the degree of conjugation for both molecules,but theα-naphthyl group of DH-2-Np-1 molecule is perpendicular to the thiophene ring,which provide poorer conjugationthan that of the correspondingβ-naphthyl modified DH-2-Np-2.3.The chiral resolution and characterization of the double helical compounds DH-1 and DH-2-Np-11)Chiral resolution and characterization of the double helical DH-1The chiral resolution of the double helix compound DH-1 has been carried out and the optimized eluentis isopropanol:hexane=0.5:99.5（v:v）.The pair of enantiomers with ee=89%and ee=84%are obtained by chiral resolution on the semi-preparative high performance liquid chromatography（HPLC）.The optical rotation of the enantiomers are-210°and+200°,and the pair of enantiomers are characterized by the circular dichroism.2)Chiral resolution and characterization of the double helical compound DH-2-Np-1The chiral resolution of the double helical compound DH-2-Np-1 has been carried out and hexane is used as the eluent.The pair of enantiomers with ee>99%were obtained by chiral resolution on the semi-preparative high performance liquid chromatography（HPLC）.The optical rotation of the enantiomers was-115°and+120°,and the pair of enantiomers are characterized by the circular dichroism4.Trial of the"cross"typed double helical compoundBy using four active sites on the thiophene ring in the DH-1 molecule,a more complex helical oligomer has been tried to synthesize.Although the"cross"typed helical compound is not successfully obtained,it provide more experience for the double helical compound preparation.