| 1-chloro-2-aryl ethynes are important intermediates for the synthesis of variousorganic and pharmaceutical compounds. They are also useful in metal-catalyzed crosscoupling reactions, such as Heck-Mizorok reactions and Cadiot-Chodkiewicz reactions.Other important reactions of1-chloro-2-aryl ethynes include cycloaddition reactionsand nucleophilic substitution reactions. Chlorination of alkynes via copper(II) chloridebegan in the end of1960s and early1970s, but so far, there is no efficient syntheticmethod to preparation1-chloro-2-aryl ethyne by copper(II) chloride. After a lot ofliterature researching, the main achievements in this thesis are as follows:1. Synthesized15kinds of aryl ethynes as chlorination substrates. Prior tochlorination of aryl ethynes to1-chloro-2-aryl ethyne by copper(II) chloride, a varietyof aryl ethynes have to be synthesized beforehand. By nitro-reduction reaction,diazotization reaction or trichloroisocyanuric acid/I2/wet SiO2system’s aromaticiodination reaction, we firstly synthesized a variety of aryl iodides. Then with thesearyl iodides, through Sonogashira reaction, we finally synthesized15kinds of arylethynes. All the compounds were characterized by1H NMR.2. Proposed an optimal substitution chlorination method. Firstly, the best ratio ofeach individual component for the preparing composite chlorinating agent was decidedby examining effects from different chlorinating agent, carrier and inorganic saltadditive. The optimal synthetic conditions were then determined through theinvestigation into the influence factors on the reaction such as solvent, the amount ofcomposite chlorinating agents, temperature and reaction time. They were as follows:composite chlorinating agent: CuCl25/3NaCl5/2Al2O3; molar ratio of aryl ethynesand composite chlorination agent:1:3; solvent: CH2Cl2; reaction temperature:35oC;reaction time:12h, which supplied the basic data of preparing1-chloro-2-aryl ethyne(Ar-C≡C-Cl).3. Synthesized15kinds of1-chloro-2-aryl ethyne. Under optimal conditions, aseries of1-chloro-2-aryl ethyne compounds1a~1o were synthesized in high yields(72~99%).These target compounds were confirmed by1H NMR,13C NMR, IR, MS andHRMS. This method is simple and mild, and shown a good specificity of substitutionchlorination without addition chlorination product. It should be mentioned that thechlorination using composite chlorinating agents is not only suitable for substrates bearing inert groups (-NO2,-X etc.) on the aromatic ring, but also those of sensitivegroups (-CHO, CH3CO-, HOCH2-,-C=N etc.). |
