本實驗室所發展出來的口夫喃成環反應可以合成出一系列不同共軛長度且具有口夫喃環與苯環交替的寡聚物，再利用兩端向外延伸的策略以期進一步得到具有特定長度的分子導線。當我們使用末端具有雙烯或雙炔基的寡聚物來作為起始物時，雙醛官能基可以藉由Heck或Sonogashira偶合反應而被快速且簡便地建立起來。
雙醛化合物對於共軛系統的延伸扮演著舉足輕重的角色。在雙醛官能基建立之後，我們可以再利用口夫喃成環反應來成功地延伸這些寡聚物的共軛系統。因此，結合了口夫喃成環反應，Heck與Sonogashira偶合反應可以對於寡聚物的系統快速地引入芳香環、雙鍵與參鍵，此合成策略是相當具有可行性的。
這個新發展出來的合成策略，對於如何由具有口夫喃環的寡聚物來進一步合成一系列具特定共軛長度的分子導線，提供了一個方便且快速的途徑。

Bidirectioonal iterative synthesis of furan-containing oligomers of different conjugation lengths leading to molecular wires is reported. Furan and benzene alternating oligomers are prepared by using our usual furan annulation approach. When the divinyloligoaryl or dialkynyloligoaryl is used, dialdehyde can be conveniently constructed by Heck or Sonogashira cross-coupling reaction.
Dialdehydes can be used for further extension of these conjugated systems. Attempts to annulate these dialdehydes with functionalized dithioacetals are found to be successful. Thus, incorporation of arylenes, double bonds, and/or triple bonds into these oligomeric systems is feasible by combining Heck or Sonogashira cross-coupling reaction with furan annulation procedure.
This newly-developed synthetic strategy affords a convenient pathway for the fast construction of a variety of furan-containing oligomers toward molecular wires.

CONTENTS
PAGE
ACKNOWLEDGEMENTS i
ABSTRACT ii
ABSTRACT (CHINESE) iii
CONTENTS iv
LIST OF FIGURES vi
LIST OF TABLES vii
1. INTRODUCTION 1
1.1. The Development of Molecular Scale Wires 1
1.2. Mixed Oligomers Consisting of Furan and Benzene Moieties 8
1.3. Synthetic Strategy of Mixed Oligomers toward Molecular Wires 10
1.4. Synthetic Aspects 15
1.4.1. Furan Annulation 15
1.4.2. Heck Reaction 17
1.4.3. Sonogashira Reaction 18
2. RESULTS AND DISCUSSION 21
2.1. Preparation of the Propargylic Dithioacetals 21
2.2. One-Pot Synthesis of the Furan-Containing Oligomers 27
2.3. Heck Reaction in Combination with Furan Annulation Approach 33
2.4. Sonogashira Reaction in Combination with Furan Annulation Approach 41
2.5. Optical, Thermal, and Electrochemical Properties 48
2.6. Conclusion 61
3. EXPERIMENTAL SECTION 62
3.1. Instrumentation and Notes on Synthetic Procedures 62
3.2. Syntheses 65
4. REFERENCES 94
APPENDIX A 1H NMR Spectra of Selected Compounds 98
APPENDIX B Mechanism of Heck Reaction 131
APPENDIX C Mechanism of Sonogashira Reaction 131
LIST OF FIGURES
PAGE
Fig. 1 A photochemically stable benzene and furan alternating oligomer 9
Fig. 2 Fluorescence spectra of compound 88, 89, 92, and 93 46
Fig. 3 Fluorescence spectra of compound 89, 96, and 97 47
Fig. 4 Fluorescence spectra of compound 92, 98, and 99 48
Fig. 5 Fluorescence spectra of compound 100, 101, 102, and 103 49
Fig. 6 Absorption spectra of 96, 97, 106, 107, and 108 in CHCl3 solution 50
Fig. 7 Absorption spectra of 97, 107, and 108 in CHCl3 solution 51
Fig. 8 Fluorescence spectra of 96, 97, 106, 107, and 108 in CHCl3 solution 52
Fig. 9 Fluorescence spectra of 97, 107, and 108 in CHCl3 solution 53
Fig. 10 TGA analysis of compound 97 55
Fig. 11 TGA analysis of compound 108 56
Fig. 12 TGA analysis of compound 107 57
Fig. 13 CV spectra of compound 96 and 106 59
Fig. 14 CV spectra of compound 97, 108, and 107 60
LIST OF TABLES
PAGE
Table 1 Screening of the yield of different electrophilic substrates in furan 31
annulation reactions
Table 2 Photophysical properties of oligoaryls 50
Table 3 Electrochemical properties of oligoaryls 58

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